Difference between revisions of "Gmaas"

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THEM FACTS ABOUT THE GREAT GMAAS
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Click the following link to redirect: [[2019 AMC 10A]]
  
- Gmaas is so interesting that an entire science has been devoted to studying him: Gmaasology.
 
  
- Gmaas is the only known living being who has a PhD in Gmaasology.
 
  
- Gmaasology is one of the most eminent fields of science, falling behind Physics, Biology, Chemistry, Economics, Geology, and Computer Programming.
 
  
- Gmaas wants his AoPS Wiki page to be the longest ever.
 
  
- Sadly, the Gmaas page is only the sixth longest page on AoPS wiki. It has around 43,000 bytes. EDIT: oof
 
  
- It turns out that Gmaas has the longest lifespan of any cat. He has lived for 314,159,265,358 years. (He is older than the universe.)
 
  
- Everyone, except for me, is Gmaas.
 
  
- Gmaas used to be a dog, but he didn't like to be a dog. So he became a cat.
 
  
- The Metropolitan Museum of Art and the Louvre are Gmaas's private art collections from 12:31 AM to 12:32 AM.
 
  
- Gmaas is Gmaas.
 
  
- Gmaas exists in <math>2\pi^2</math> dimensions because he doesn't like string theory.
 
  
- Christmas was actually supposed to be called Gmaasmas.
 
  
- Pi is a representation of how many pies Gmaas has eaten. EDIT: The number pi was created by Gmaas. He took a ten-sided die and flipped it an infinite number of times. The numbers he rolled became the digits of pi.
 
  
- Gmaas is the creator of everything.
 
  
- According to recent DNA tests, famous historical people, such as Euclid, Julius Caesar, Omar Khayyam, George Washington, and Ramanujan are actually Gmaas in disguise.
 
  
- Gmaas is a cat. EDIT: How many times do we say this?
 
  
- Gmaas has the following powers: trout, carp, earthworm, and catfish. Gmaas never uses any of them because Gmaas has an infinite number of powers. EDIT: He has used his catfish power several times.
 
  
- Gmaas was once spotted in minecraft chewing a tree. EDIT: The tree broke.
 
  
- Gmaas once broke a Nokia.
 
  
- Gmaas was spotted in Roblox eating a tacocat.
 
  
- Gmaas would like to go to Taco Bell, but Gmaas goes to Wendy's instead. No one knows why.
 
  
- Gmaas real name is Grayson Maas. He is the CEO of AoPS. EDIT: Gmaas's real name is Gmaas.
 
  
- Gmaas has a pet pufferfish named Pafferfash. EDIT: He also has a goldfish named Sylgar (D&D reference).
 
  
- Gmaas has colonized the universe.
 
  
- Some people think that Gmaas is a human. However, this has never been proven. Many AoPSers believe Gmaas is a cat. EDIT: He is a cat. EDIT EDIT: yeah we've said that already.
 
  
- Gmaas started pastafarianism. you only eat pasta.
 
  
- Gmaas can eat your hand, but he probably won't because hands taste bad.
 
  
- According to the Interuniversal Gmaas Society, 17.548 percent of universe's population thinks that Gmaas is spelled "Gmass".
 
  
- The Interuniversal Society was founded in 1314 on May 9th at 2:06:53 PM. EDIT: Ever since then, Gmaas day has been celebrated on May 9th.
 
  
- The Interuniversal Gmaas Society is currently trying to reconstruct a lost book about Gmaas from Lucretius's De Rerum Natura. They have been researching this for three years. EDIT: A few years ago the Society compiled a biography of Gmaas's last twenty lives. EDIT EDIT: The only copies of this biography are locked in the Gmaasian Library beneath the Library of Congress.
 
  
- Gmaas likes to surprise unsuspecting people.
 
  
- Gmaas loves sparkly mechanical pencils. EDIT: Gmaas has eaten several mechanical pencils.
 
  
- The bible of Gmaas is this page, and people go to worship Gmaas in the Maas. EDIT: This is an unusual bible where everyone edits it.
 
  
- Gmaas is said to taste like a furry meatball.
 
  
- Gmaas's favorite food is pepperoni pizza.
 
  
- Gmaas is Johnny Johnny's Papa. EDIT: We'll never know.
 
  
- Gmaas is in you, and Gmaas is in you, and Gmaas is in me. EDIT: Gmaas is in all cats.
 
  
- Gmaas always remembers not to destroy the universe. EDIT: He forgot a few centuries ago and had to travel back in time to stop it.
 
  
- Gmaas created many user's accounts. EDIT: 31.4159...% of account on AoPS are Gmaas in disguise.
 
  
- Gmaas is both living and nonliving. EDIT: He is living 90% of the time.
 
  
- Gmaas is quasiomnipotent. He cannot comprehend the stupidity of humans.
 
  
- ALL HAIL THE GMAAS CLOUD!! EDIT: Gmaas is a cloud: a cloud of electrons and nuclei.
 
  
- Some things are beyond possible human comprehension. Nothing is beyond Gmaas.
 
  
- Gmaas eats food and resides at King Arthur's throne when he feels like it.
 
  
- Gmaas owns a rabbit.
 
  
- Gmaas is both singular and plural. EDIT: It is usually singular.
 
  
- Gmaas eats disbelievers as if they were donuts for breakfast. (Yet I'm somehow still alive. Do you think Gmaas actually ate my soul?) EDIT: Yes, I do.
 
  
- Gmaas knows Jon Snow's parents.
 
  
- Gmaas is Aegon VI Targaryen.
 
  
- Gmaas created the Marvel Universe.
 
  
- All Gmaas article editors will be escorted to Gmaas heaven after they die. EDIT: I hope so.
 
  
- Gmaas won all the wars. EDIT: He did not win the Intergmaasian War, which was between Gmaas's head and his tail. His tail won. Two flees died in the war.
 
  
- Gmail was named after Gmaas. EDIT: Google was named after Gmaas. EDIT EDIT: Almost every word starting with G is named after Gmaas.
 
  
- Gmaas disapproves of the DC universe.
 
  
- Gmaas ate cat-food today.
 
  
- Gmaas won Battle For Dream Island and Total Drama Island.
 
  
- Somehow Gmaas exists at all places at the same time. EDIT: Gmaas does not exist in my kitchen.
 
  
- Gmaas can lift with Gmaas's will. EDIT: Gmaas can lift with no one's will while he is sleepwalking.
 
  
- Gmaas is the rightful heir to the Iron Throne.
 
  
- Gmaas was once a card in Clash Royale but it was too OP so they had to remove it.
 
  
- Gmaas is actually Teemo in League of Legends because Gmaas made LoL and they made a honorary Gmaas character.
 
  
- Gmaas started the Game of Thrones.
 
  
- Gmaas will also end the Game of Thrones.
 
  
- Gmaas killed himself hundreds of times. He was reincarnated as a different species each time.
 
  
- Gmaas is Azor Ahai.
 
  
- Gmaas created everything after puking.
 
  
- Gordan's last name was named after Gmaas.
 
  
- Gmaas is more powerful than Gohan.
 
  
- Gmaas is over 90000 years old. EDIT: Gmaas is trillions of years old.
 
  
- Gmaas has 100000000000000000000000000000000000000000000000 cat lives, maybe even more. Gmaas has 0 dog lives. EDIT: He has 314,159,265 fish lives.
 
  
- Who wrote Harry Potter? None other than Gmaas himself.
 
  
- Gmaas created the catfish. EDIT: Out of Gmaas's 314,159,265 fish lives, 271,828,182 are catfish lives. He has used up 141,421,356 of them.
 
  
- Gmaas has proven that the universe is infinite and has traveled to the edge of the universe in 1 second.
 
  
- Gmaas founded Target, but then Gmaas sued them for making the mascot look like a dog when it was supposed to look like Gmaas. EDIT: They went broke because Gmaas sued them but then Gmaas ate a fudge popsicle that made him super hyper and he made Target not broke anymore in his hyperness.
 
  
- Everyone has a bit of Gmaas inside them. EDIT: I don't. EDIT EDIT: Yes, you do.
 
  
- Gmaas likes to eat popsicles. Especially the fudge ones that get him hyper. EDIT: Gmaas is a popsicle.
 
  
- When Gmaas is hyper Gmaas runs across Washington D.C. grabbing unsuspecting pedestrians, steals their phones, hacks into them, and downloads PubG onto their phone.
 
  
- Gmaas's favorite cereal is fruit loops. Gmaas thinks it tastes like unicorns jumping on rainbows.
 
  
- Gmaas thinks that the McChicken has way too much mayonnaise.
 
  
- Gmaas is a champion pillow-fighter.
 
  
- Gmaas colonized Mars. EDIT: Gmaas also colonized Jupiter, Pluto, and several other galaxies. Gmaas cloned some little Gmaas robots (with Gmaas's amazingly robotic skill of coding) and put them all over a galaxy called Gmaasalaxy. EDIT EDIT: Gmaas has colonized the universe.
 
  
- Gmaas has the ability to make every device play "The Duck Song" at will. EDIT: "The Duck Song" was copied off of the "Gmaas song," but the animators though Gmaas wasn't catchy enough.
 
  
- Gmaas once caught the red dot and ate it. EDIT: Gmaas is a red dot.
 
  
- Gmaas's favorite color is neon.
 
  
- Gmaas can create wormholes and false vacuums.
 
  
- Gmaas is a champion pvp Minecraft player.
 
  
- Gmaas is the coach of True Ninja Music and Myth.
 
  
- Gmaas caught a CP 6000 Mewtwo with a normal Pokeball in Pokemon Go.
 
  
- Gmaas founded Costco.
 
  
- Gmaas does not need to attend the FIFA World Cup. If Gmaas did, Gmaas would automatically beat any team.
 
  
- Gmaas can solve any puzzle instantly besides the 3x3 Rubik's Cube.
 
  
- Gmaas caught a CP 20,000 Mewtwo with a normal Pokeball and no berries blindfolded first try in Pokemon Go.
 
  
- When Gmaas flips coins, they always land tails, except once when Gmaas was making a bet with Zeus.
 
  
- On Gmaas's math tests, Gmaas always gets <math>\infty</math>.
 
  
- Gmaas's favorite number is pi. It's also one of Gmaas's favorite foods.
 
  
- Gmaas's burps created all gaseous planets.
 
  
- Gmaas beat Luke Robatille in an epic showdown of catnip consumption.
 
  
- Gmaas's wealth is unknown, but it is estimated to be way more than Scrooge's. EDIT: It may be more than John D. Rockefeller.
 
  
- Gmaas has a summer house on Mars.
 
  
- Gmaas has a fall house on Venus.
 
  
- Gmaas has a winter house on Jupiter.
 
  
- Gmaas has a spring house on Earth.
 
  
- The Earth and all known planets are simply Gmaas's hairballs.
 
  
- Gmaas attended Harvard, Yale, Stanford, MIT, UC Berkeley, Princeton, Columbia, and Caltech at the same time using a time-turner.
 
  
- Gmaas also attended Hogwarts and was a prefect. EDIT: Gmaas was headmaster.
 
  
- Mrs. Norris is Gmaas's archenemy.
 
  
- Gmaas is a demigod and attends Camp Half-Blood over summer. Gmaas is the counselor for the Apollo cabin because cats can be demigod counselors too.
 
  
- Gmaas has completed over 2,000 quests and is very popular throughout Camp Half-Blood. Gmaas has also been to Camp Jupiter.
 
  
- Percy Jackson was only able to complete his quests because Gmaas helped him.
 
  
- Gmaas painted the Mona Lisa, The Last Supper, and A Starry Night.
 
  
- Gmaas knows that their real names are Gmaasa Lisa, The Last Domestic Meal, and Far-away Light.
 
  
- Gmaas attended all the Ivy Leagues.
 
  
- I am Gmaas.
 
  
- I am also Gmaas.
 
  
- In 2018 Gmaas once challenged Magnus Carlsen to a chess match. Gmaas won every game.
 
  
- But it is I who am Gmaas.
 
  
- Gmaas is us all.
 
  
- Gmaas is all of us yet none of us. EDIT: Gmaas is a cat.
 
  
- Gmaas was captured in 2017 but was released due to sympathy. EDIT: Gmaas was only captured his concrete form; his abstract form cannot be processed by a feeble human brain.
 
  
- Gmaas's fur is white, black, grey, yellow, red, blue, green, brown, pink, orange, turquoise, and purple at the same time.
 
  
- Gmaas crossed the event horizon of a black hole and ended up in the AoPS universe.
 
  
- Gmaas crossed the Delaware River with Washington.
 
  
- Gmaas crossed the Atlantic with the pilgrims.
 
  
- If you are able to capture a Gmaas hair, Gmaas will give you some of his Gmaas power.
 
  
- Chuck Norris makes Gmaas jokes. EDIT: Those jokes all praise Gmaas.
 
  
- Gmaas is also the ruler of Oceania, Eastasia, and Eurasia. EDIT: Gmaas wrote the book "1984."
 
  
- Gmaas killed Big Brother by farting on him. Though Gmaas was caught by the Ministry of Love, Gmaas escaped easily. EDIT: Gmaas used to be Big Brother.
 
  
- Gmaas destroyed the Ministry of Love.
 
  
- Gmaas was not affected by Thano's snap; in fact Gmaas is the creator of the Infinity Stones.
 
  
- Everyone knows that Gmaas is a god.
 
  
- Gmaas also owns Animal Farm. Napoleon was Gmaas's servant.
 
  
- Gmaas is the only person who knows where Amelia Earhart is.
 
  
- Gmaas is the only cat that has been proven transcendental.
 
  
- Gmaas happened to notice http://artofproblemsolving.com/community/c402403h1598015p9983782 and is not very happy about it.
 
  
- Grumpy cat reads Gmaas memes. EDIT: Grumpy cat then steals them and claims they're his. Gmaas isn't very happy about that, either.
 
  
- The real reason why AIME cutoffs aren't out yet is because Gmaas refused to grade them due to too much problem misplacement.
 
  
- Gmaas dueled Grumpy Cat and won. Gmaas wasn't trying. EDIT: Gmaas killed Grumpy cat.
 
  
- Gmaas sits on the statue of Pallas and says forevermore. EDIT: When Gmaas was a statue, people hid him in a basement and forgot about him. Then civilization collapsed and the Middle Ages began. People finally discovered and melted down the statue of Gmaas in 1350. Gmaas was free and reincarnated again, bringing about the Renaissance.
 
  
- Gmaas is a big fan of Edgar Allan Poe because he is actually Poe. EDIT: He became Poe during his thirty-year depression in the 19th century.
 
  
- Gmaas does merely not use USD; he owns it.
 
  
- Gmaas really knows that Roblox is awful and does not play it seriously; thank Gmaas our lord is sane.
 
  
- The only god is Gmaas.
 
  
- In 2003, Gmaas used elliptical curves to force his reign over AoPS.
 
  
- "Actually, my name is spelled "GMAAS". (Citation needed)
 
  
- Gmaas is the smartest living being in the universe.
 
  
- Gmaas helped Sun Wukong on the Journey to the West.
 
  
- Gmaas was the creator of Wikipedia.
 
  
- It is said Gmaas could hack any website he desires.
 
  
- Gmaas is the basis of Greek and Egyptian mythology. EDIT: He is also the basis for Aztec mythology. He once had a craving for humans, so he created human sacrifice.
 
  
- Gmaas once sold Google to a man for around <math>12</math> dollars! EDIT: Gmaas has not spent those <math>12</math> dollars and is waiting for the economy to crash.
 
  
- Gmaas uses a HP printer. It is specifically a HP 21414144124124142141414412412414214141441241241421414144124124142141414412412414 printer.
 
  
- Gmaas owns all AoPS staff including Richard Rusczyk.
 
  
- Richard Rusczyk is one of Gmaas's many code names.
 
  
- Gmaas was there when Yoda was born. EDIT: Gmaas is Yoda's father.
 
  
- Gmaas's true number of lives left is unknown; however, Gmaas recently confirmed that he had at least one left. Why doesn't Gmaas have so many more lives than other cats? The power of Gmaas. EDIT: This is all not true. EDIT EDIT: This is all true.
 
  
- sseraj once spelled Gmaas as gmASS by accident in Introduction to Geometry (1532).
 
  
- Gmaas actively plays Roblox, and is a globally ranked professional gamer: https://www.roblox.com/users/29708533/profile... but he hates Roblox.
 
  
- Gmaas has beaten Chuck Norris and The Rock and John Cena all together in a fight.
 
  
- Gmaas is a South Korean, North Korean, Palestinian, Israeli, U.S., Soviet, Russian, and Chinese citizen at the same time. EDIT: Gmaas is a citizen of every country in the world. Gmaas seems to enjoy the country of AOPS best, however.
 
  
- "I am sand" destroyed Gmaas in FTW.
 
  
- sseraj posted a picture of Gmaas with a game controller in Introduction to Geometry (1532).
 
  
- Gmaas plays Roblox mobile edition and likes Minecraft, Candy Crush, and Club Penguin Rewritten. He also <math>\boxed{\text{loves}}</math> Catch that fish.
 
  
- Gmaas is Roy Moore's horse in the shape of a cat.
 
  
- Gmaas is a known roblox/club penguin rewritten player and is a legend at it. He has over <math>289547987693</math> robux and <math>190348</math> in CPR.
 
  
- This is all hypothetical. EDIT: This is all factual. For reference, see an earlier post.
 
  
- Gmaas's real name is Princess. He has a sibling named Rusty/Fireheart/Firestar. EDIT: That is incorrect.
 
  
- He is capable of salmon powers.
 
  
- The Gmaas told Richard Rusczyk to make AoPS.
 
  
- The Gmaas is everything. Yes, you are part of the Gmaas-Dw789. EDIT: Gmaas is older than the universe. He is more than everything.
 
  
- The Gmaas knows every dimension up to 9999999999999999999999999999999999999999999999999999999999999999999999999999999999th dimension. EDIT: He is working on the higher dimensions presently. It takes up 1% of his time. He spends the remaining 99% of his time eating, sleeping, and being.
 
  
- He went into a black hole, entered the white hole, got into dimension 15 where people drink tea every day, and stole 154 buckets of tea.
 
  
- Gmaas is "TIRED OF PEOPLE ADDING TO HIS PAGE!!" (Maas 45). EDIT: This is Gmaas's bible, so he wants to have a longer version. For reference, see Maas 3141592653589793238462.
 
  
- Gmaas is a Gmaas who is actually Gmaas.
 
  
- Gmaas has a penguin servant who runs GMAASINC. The penguin may or may not be dead. He had another penguin, who is most alive.
 
  
- Gmaas owns a TARDIS, and can sometimes be seen traveling to other times for reasons unknown.
 
  
- Gmaas knows how to hack into top secret AoPS community pages.
 
  
- Gmaas was a river clan cat who crossed the event horizon of a black hole and came out the other end.
 
  
- Gmaas is king of the first men, the anduls.
 
  
- Gmaas is a well known professor at Meowston Academy. EDIT: He is professor of Gmaasology.
 
  
- Gmaas founded Meowston Academy.
 
  
- Gmaas is the CEO of Caterpillar.
 
  
- Gmaas drinks at Starbucks everyday.
 
  
- Gmaas is a tuna addict, along with other more potent fish, such as salmon and trout.
 
  
- Gmaas likes turning into fish and catching himself.
 
  
- Gmaas won the reward of being cutest and fattest cat ever--he surpassed grumpy cat. (He also out-grumped grumpy cat!!!) EDIT: He is in the Guinness Book of World Records for fluffiest cat ever.
 
  
- Last sighting 1665 Algebra-A 3/9/18 at 9:08 PM.
 
  
- He is the owner of sseraj, not pet.
 
  
- The embodiment of life and universe and beyond.
 
  
- Gmaas watches memes of Gmaas.
 
  
- After Death Gmaas became the GOD OF HYPERDEATH and obtained over 9000 souls.
 
  
- Gmaas invented Rick Rolling.
 
  
- Gmaas's real name is Pablo Diego José Francisco de Paula Juan Nepomuceno María de los Remedios Cipriano de la Santísima Trinidad Ruiz y Picasso [STOP RICK ROLLING. (Source)].
 
  
- Gmaas is a certified Slytherin.
 
  
- Gmaas once slept on sseraj's private water bed, so sseraj locked him in the bathroom.
 
  
- Gmaas has superpowers that allow him to overcome the horrors of Mr. Toilet (while he was locked in the bathroom).
 
  
- Gmaas once sat on an orange on a pile of AoPS books, causing an orange flavored equation explosion.
 
  
- Gmaas once conquered the moon and imprinted his face on it until asteroids came.
 
  
- Gmaas is a supreme overlord who must be given <math>10^{1000000000000000000000^{1000000000000000000000}}</math> minecraft DIAMONDS.
 
  
- Gmaas is the Doctor Who lord, sports Dalek-painted cars, and eats human finger cheese, custard, and black holes.
 
  
- Gmaas is everyone's favorite animal.
 
  
- Gmaas is an animal.
 
  
- Gmaas lives with sseraj.
 
  
- Gmaas dislikes number theory but enjoys geometry.
 
  
- Gmaas is cool.
 
  
- He is often overfed (with probability <math>\frac{3972}{7891}</math>), or malnourished (with probability <math>\frac{3919}{7891}</math>) by sseraj.
 
  
- He has <cmath>\sum_{k=1}^{267795} [k(k+1)]+GMAAS+GMAAAAAAAS</cmath> supercars, excluding the Purrari and the 138838383 Teslas.
 
  
- He employs AoPS.
 
  
- Gmaas is the reason why AoPS exists.
 
  
- He is a Gmaas with yellow fur and white hypnotizing eyes.
 
  
- Gmaas has the ability to divide by zero. EDIT: Gmaas knows what 1/0 is. What is it? We'll never know.
 
  
- He was born with a tail that is a completely different color from the rest of his fur.
 
  
- His stare is very hypnotizing and effective at getting table scraps.
 
  
- His stare turned Medusa into rock, King Midas into gold, and sseraj into sseraj.
 
  
- He sometimes appears several minutes before certain classes start as an admin.
 
  
- Gmaas is an AoPS administrator under the alias Grayson Maas.
 
  
- He died from too many Rubik's cubes in an Introduction to Algebra A class, but he got revived by the Dark Lord at 00:13:37 AM the next day.
 
  
- It is uncertain whether or not he is a cat or is merely some sort of beast that has chosen to take the form of a cat (specifically a Persian Smoke).
 
  
- Actually, Gmaas is a cat. Gmaas said so, and science says so.
 
  
- He is distant relative of the chair of the department of Gmaasology at Princeton.
 
  
- Gmaas cannot be Force choked. Darth Vader learned that the hard way...
 
  
- Gmaas is very famous now, and mods always talk about him before class starts.
 
  
- His favorite food is AoPS textbooks because they help him digest problems.
 
  
- Gmaas wrote all AoPS textbooks but is not listed in the acknowledgments section.
 
  
- Gmaas tends to reside in sseraj's fridge.
 
  
- Gmaas once ate all sseraj's fridge food, so sseraj had to put him in the freezer.
 
  
- The fur of Gmaas can protect him from the harsh conditions of a freezer.
 
  
- Then he ate all the food in sseraj's freezer. He enjoyed the ice cream in the freezer the most.
 
  
- He also ate Gmaas's freezer.
 
  
- Gmaas once demanded Epic Games to give him 5,000,000 V-bucks for his 569823rd birthday. EDIT: This is why he does not have an Epic Games account anymore. EDIT EDIT: Gmaas created Epic games, though.
 
  
- Gmaas sightings are not very common. There have only been 30 confirmed sightings of Gmaas in the wild.
 
  
- Gmaas is a sage omniscient cat.
 
  
- Gmaas is looking for suitable places other than sseraj's fridge to live in.
 
  
List of places where Gmaas sightings have happened:
 
  
- The Royal Scoop ice cream store in Bonita Beach Florida
 
  
- Inside the abandoned hospital on Rosevelt Island in New York City, which is also a feral cat sanctuary.
 
  
- MouseFeastForCats/CAT 8 Mouse Apartment 1083
 
  
- Prealgebra 2 (1440)
 
  
- Alligator Swamp A 1072
 
  
- Alligator Swamp B 1073
 
  
- Prealgebra A (1488)
 
  
- Introduction to Algebra A (1170)
 
  
- Introduction to Algebra B (1529)
 
  
- Welcome to Panda Town Gate 1076
 
  
- Welcome to Gmaas Town Gate 1221
 
  
- Welcome to Gmaas Town Gate 1125
 
  
- 33°01'17.4"N 117°05'40.1"W (Rancho Bernardo Road, San Diego, CA)
 
  
- The other side of the ice in Antarctica
 
  
- Feisty Alligator Swamp 1115
 
  
- Introduction to Geometry 1221 (Taught by sseraj)
 
  
- Introduction to Counting and Probability 1142
 
  
- Feisty-ish Alligator Swamp 1115 (AGAIN)
 
  
- Intermediate Counting and Probability 1137
 
  
- Intermediate Counting and Probability 1207
 
  
- Posting student surveys
 
  
- USF Castle Walls - Elven Tribe 1203
 
  
- The Dark Lord's Hut 1210
 
  
- AMC 10 Problem Series 1200
 
  
- Intermediate Number Theory 1138
 
  
- Intermediate Number Theory 1476
 
  
- Introduction To Number Theory 1204. Date:7/27/16.
 
  
- Algebra B 1112
 
  
- Intermediate Algebra 1561 7:17 PM 12/11/16
 
  
- Nowhere Else, Tasmania
 
  
- Earth Dimension C-137
 
  
- Geometry 1694 at 1616 PST military time. There was a boy riding him, and he seemed extremely miffed.
 
  
- Intermediate Algebra 1710 9/24/2018
 
  
- Introduction to Geometry 1369
 
  
- Introduction to Counting & Probability 1177
 
  
- These have all been designated as the most glorious sections of AoPSland now (especially the USF castle walls), but deforestation is so far from threatens the wild areas (i.e. Alligator Swamps A&B).
 
  
- Gmaas has also been sighted in Olympiad Geometry 1148.
 
  
- Gmaas has randomly been known to have sent his minions into Prealgebra 2 1163. However, the danger is passed; that class is over.
 
  
- Gmaas once snuck into sseraj's email so he could give a future Gmaasologist an extension in Introduction to Number Theory 1204. This was 1204 minutes after his sighting on 7/27/16.
 
  
- Gmaas also has randomly appeared on top of the USF's Tribal Bases(he seems to prefer the Void Tribe). However, the next day there is normally a puddle in the shape of a cat's underbelly wherever he was sighted. Nobody knows what this does. EDIT: Nobody has yet seen him atop a tribal base yet.
 
  
- Gmaas is often under the disguise of a penguin or cat. Look out for them. EDIT: Gmaas rarely disguises himself as a penguin. EDIT EDIT: He is a cat.
 
  
- Many know that leafy stole dream island. In truth, after leafy stole it, Gmaas stole it himself. (BFDI Reference)
 
  
- He lives in the shadows. Is he a dream? Truth? Fiction? Condemnation? Salvation? AoPS site admin? He is all these things and none of them. He is... Gmaas. EDIT: He is an AoPS site admin. EDIT EDIT: He exists.
 
  
- If you make yourself more than just a cat... if you devote yourself to an ideal... and if they can't stop you... then you become something else entirely. A LEGEND. Gmaas now belongs to the ages. EDIT: Gmaas belongs to Gmaas.
 
  
- Is this the real life? Is this just fantasy? No. This is Gmaas, the legend. EDIT: This is real life.
 
  
- Aha!! An impostor!!
 
  
http://www.salford.ac.uk/environment-life-sciences/research/applied-archaeology/greater-manchester-archaeological-advisory-service
 
  
(Look at the acronym.)
 
  
GREATER MANCHESTER ARCHAEOLOGICAL ADVISORY SERVICE EDIT: The above fact is slightly irrelevant. EDIT EDIT: The previous edit is slightly irrelevant.
 
  
- Gmaas might have been viewing (with a <math>\frac{99999.\overline{9}}{100000}</math> chance) the Ultimate Survival Forum. He (or is he a she?) is suspected to be transforming the characters into real life. Be prepared to meet your epic swordsman self someday. If you do a sci-fi version of USF, then prepare to meet your Overpowered soldier with amazing weapons one day.
 
  
- Gmaas is neither he nor she, Gmaas is above gender. EDIT: Gmaas is above your door.
 
  
- Gmaas is love; Gmaas is life.
 
  
- The name of Gmaas is so powerful it radiates Deja Mew.
 
  
- Gmaas is on the list of "Elusive Creatures." If you have questions or want the full list, contact Gmaas himself.
 
  
- Gmaas can be summoned using the <math>\tan(90)</math> ritual. Draw a pentagram and write the numerical value of <math>\tan(90)</math> in the middle, and he will be summoned. EDIT: The above fact is incorrect. A ueser has done this and commented with screenshot proof at the below link, but Gmaas was not summoned. https://artofproblemsolving.com/community/c287916h1291232 EDIT EDIT: The above 'proof' is non-conclusive. The user had only put an approximation.
 
  
- Gmaas's left eye contains the singularity of a black hole if and only if everyone in the world blinks at the same time within a nanosecond. EDIT: That has never happened and thus it does not contain the singularity of a black hole.
 
  
- Lord Grindelwald once tried to make Gmaas into a Horcrux, but Gmaas's fur is protected by the Elder Wand and secure.
 
  
- Despite common belief, Harry Potter did not defeat Lord Voldemort. Gmaas did.
 
  
- The original owner of Gmaas was Gmaas.
 
  
- Gmaas was not the fourth Peverell brother, but he ascended into a higher being and now he resides in the body of a cat, as he was before. Is it a cat? We will know. (And the answer is YES.) EDIT: He wasn't the fourth Peverell brother, but he was a cousin of theirs, and he advised Ignotus to give up his cloak.
 
  
- It is suspected that Gmaas may be ordering his cyber hairballs to take the forums, along with microbots. EDIT: His fur is so long that it generates thousands of micro-hairballs per day.
 
  
- Gmaas rarely frequents the headquarters of the Illuminati. He was their symbol for one yoctosecond, but he soon decided that the job was too low for his power to be wasted on.
 
  
- It has been wondered if Gmaas is the spirit of Obi-Wan Kenobi or Anakin Skywalker in a higher form, due to his strange capabilities and powers. EDIT: Gmaas is neither Anakin Skywalker or Obi-Wan Kenobi as he is trillions of years older. EDIT EDIT: Anakin Skywalker and Obi-Wan Kenobi could have been Gmaas in another form.
 
  
- Gmaas has a habit of sneaking into computers, joining The Network, and exiting out of some other computer. EDIT: Gmaas invented the first computer. He gave it to Charles Babbage for his birthday.
 
  
- It has been confirmed that Gmaas uses gmewal as his email service.
 
  
- Gmaas has a bright orange tail with hot pink spirals. Or he had for 15 minutes. That was the 15 minutes after he tried to play Taylor Swift music on his 34,000 year old MP3 player in front of sseraj, who, at the time, was handling a bucket of dangerous, radioactive material.
 
  
- Gmaas is well known behind his stage name, Michael Stevens (also known as Vsauce XD), or his page name, Purrshanks. EDIT: Crookshanks was his brother.
 
  
- Gmaas watchers know that the codes above are NOT years. They are secret codes for the place. But if you've edited that section of the page, you know that. EDIT: The above post is false. The post before the above post has an unknown truth value.
 
  
- Gmaas is a good friend of the TARDIS and the Millennium Falcon.
 
  
- In the Dark Lord's hut, Gmaas was seen watching Doctor Who. Anyone who has seen the Dark Lord's hut knows that both Gmaas and the DL (USF code name of the Dark Lord) love BBC. How Gmaas gave him a TV may be lost to history. And it has been lost.
 
  
- The TV has been noticed to be invincible. Many USF weapons, even volcano rings, have tried (and failed) to destroy it. The last time it was seen was on a Kobold display case outside of a mine. The display case was crushed, and a report showed a spy running off with a non-crushed TV.
 
  
- The reason why Dacammel left the USF is that gmaas entrusted his TV to him, and not wanting to be discovered by LF, Cobra, or Z9, dacammel chose to leave the USF, but is regretting it, as snakes keep spawning from the TV. EDIT: The above fact is somewhat irrelevant. EDIT EDIT. Dacammel gave the TV back to gmaas, and he left the dark side and their cookies alone. EDIT EDIT EDIT: The above fact is relevant. EDIT EDIT EDIT EDIT: Is this the longest chain of edits on AoPS Wiki? EDIT EDIT EDIT EDIT EDIT: Yes. EDIT EDIT EDIT EDIT EDIT EDIT: It is.
 
  
- Gmaas is a Super Duper Uper Cat Time Lord. He has <math>57843504</math> regenerations and has used <math>3</math>. <cmath>9\cdot12\cdot2\cdot267794=57843504</cmath>.
 
  
- Gmaas highly enjoys destroying squeaky toys until he finds the squeaky part, then destroys the squeaky part.
 
  
- In that way Gmaas is similar to a dog.
 
  
- Gmaas loves to eat turnips. At <math>\frac{13}{32}</math> of the sites he was spotted at, he was seen with a turnip.
 
  
- Gmaas has a secret hidden garden full of turnips under sseraj's house.
 
  
- sseraj is "Gmaas's person."
 
  
- Gmaas has three tails, one for everyday life, one for special occasions, and one that's invisible.
 
  
- Gmaas is a dangerous creature. If you ever meet him, immediately join his army or you will be killed. EDIT: If you ever meet Gmaas, scratch him on the ears. Most cats enjoy that.
 
  
- Gmaas is in alliance with the Cult of Skaro. How did he get an alliance with ruthless creatures that want to kill everything in sight? Nobody knows (except him), not even the leader of the Cult of Skaro.
 
  
- Gmaas lives in Gallifrey and in Gotham City (He has sleepovers with Batman).
 
  
- Gmaas is an excellent driver. EDIT: He was to one who designed the driver's license test, although he didn't bother with the permit test. EDIT EDIT: He invented the first car in 1600, but it sunk in the Pacific Ocean.
 
  
- The native location of Gmaas is the twilight zone.
 
  
- Donald Trump once sang "All Hail the Chief" to Gmaas, 3 days after being sworn in as US President.
 
  
- Gmaas likes to talk with rrusczyk from time to time.
 
  
- Gmaas is the reason why the USF has the longest thread on AoPS.
 
  
- sseraj, in 1521 Introduction to Number Theory, posted an image of Gmaas after saying "Who wants to see 5space?" at around 5:16 PM Mountain Time, noting Gmaas was "also 5space". EDIT: He also did it in Introduction to Algebra A once.
 
  
- Gmaas is not retarded. EDIT: Gmaas is actually the smartest living being on the planet.
 
  
- In 1521 Into to Number Theory, sseraj posted an image of a 5space Gmaas fusion. (First sighting)
 
  
- Also confirmed that Gmaas doesn't like ketchup because it was the only food left the photo.
 
  
- In 1447 Intro to Geometry, sseraj posted a picture of Gmaas with a Rubik's cube suggesting that Gmaas's has an average solve time of <math>-GMAAS</math> seconds.
 
  
- Gmaas beat Superman in a fight with ease.
 
  
- Gmaas was an admin of Roblox. EDIT: He created Roblox.
 
  
- Gmaas traveled around the world, paying so much <math>MONEY</math> just to eat. :D
 
  
- Gmaas is a confirmed Apex predator and should not be approached, unless in a domestic form.
 
  
Summary of Gmaas's many powers and deeds:
 
  
- When Gmaas subtracts <math>0.\overline{99}</math> from <math>1</math>, the difference is greater than <math>0</math>.
 
  
- Gmaas was shown to have fallen on Wed Aug 23 2017: https://ibb.co/bNrtmk https://ibb.co/jzUDmk
 
  
- Gmaas died on August, 24, 2017, but one of his friends revived him after about 2 mins of being dead.
 
  
- The results of the revival are top secret, and nobody knows what happened.
 
  
- sseraj, in 1496 Prealgebra 2, said that Gmaas is Santacat.
 
  
- sseraj likes to post a picture of Gmaas in every class he passes by. EDIT: sseraj always posts pictures of Gmaas in cat form, never in polar bear form. EDIT EDIT: Gmaas is rarely in polar bear form.
 
  
- sseraj posted a picture of Gmaas as an Ewok, suggesting he resides on the moon of Endor. Unfortunately, the moon of Endor is also uninhabitable ever since the wreckage of the Death Star changed the climate there. It is thought Gmaas is now wandering space in search for a home. EDIT: What evidence is there Endor was affected? Other Ewoks still live there. EDIT EDIT: Also, Gmaas doesn't care. He can live there no matter what the climate is. EDIE EDIT EDIT: Gmaas is omnipotent and can live anywhere he wants during his many lives.
 
  
- Gmaas is the lord of the pokemans.
 
  
- Gmaas can communicate with, and sometimes control any other cats; however, this is very rare, as cats normally have a very strong will.
 
  
- Picture of Gmaas http://i.imgur.com/PP9xi.png
 
  
- Gmaas is known by Mike Miller.
 
  
- Gmaas got mad at sseraj once, so sseraj locked Gmaas in sseraj's freezer.
 
  
- Then, sseraj decided to eat all of Gmaas's hidden turnips in the freezer as punishment. EDIT: sseraj could not eat all of them so, he put the remaining turnips in the fire.
 
  
- Gmaas ate a pie.
 
  
- A Gmaas bite is 7000 psi.
 
  
- Many people have met Gmaas.
 
  
- It has been confirmed that Gmaas can talk.
 
  
- Gmaas likes to eat fur.
 
  
- Gmaas is bigger than an ant.
 
  
- Gmaas once ate the king of the ants. EDIT: Ants do not have kings; they have queens.
 
  
- Gmaas lives somewhere over the rainbow. EDIT: He lives in sseraj's house.
 
  
- Gmaas is an obviously omnipotent cat.
 
  
- sseraj is known to post pictures of Gmaas on various AoPS classrooms. It is not known if these photos have been altered with the editing program called 'Photoshop.'
 
  
- sseraj has posted pictures of Gmaas in Introduction to Algebra before class started with the title "caption contest." Anyone who posted a caption mysteriously vanished in the middle of the night. EDIT: This has happened many times, including in Introduction to Geometry 1533, among other active classes. The person writing this did participate, and did not disappear. (You could argue Gmaas is typing this through his/her account...)
 
  
- Gmaas has once slept in your bed and made it gray.
 
  
- It is rumored that Richard Rusczyk is actually Gmaas in disguise. EDIT: That is false. Gmaas is only in one form at a time.
 
  
- Gmaas is suspected to be a cat in disguise.
 
  
- Gmaas is a cat but has characteristics of every other animal on Earth. EDIT: Gmaas does not have the characteristic of being able to eat plankton.
 
  
- Pegasus was modeled off Gmaas. EDIT: Pegasus used to be Gmaas's pet, but Pegasus escaped and joined Bellerophon.
 
  
- Gmaas is the ruler of the universe and has been known to be the creator of the species "Gmaasians".
 
  
- There is a rumor that Gmaas is starting a poll.
 
  
- Gmaas is a rumored past ThunderClan cat who ran away, founded GmaasClan, then became a kittypet.
 
  
- There is a rumored sport called "Gmaas Hunting" where people try to successfully capture Gmaas in the wild with video/camera/eyes. Strangely, no one has been able to do this, and those that have have mysteriously disappeared into the night. Nobody knows why. Many people have tried Gmaas Hunting, but they never have been successful.
 
  
- Gmaas burped and caused an earthquake.
 
  
- Gmaas once drank from a teacup.
 
  
- GMAAS IS HERE.... PURRRRRRRRRRRRRRRRRRRR EDIT: Gmaas is everywhere.
 
  
- Gmaas made, and currently owns the Matrix.
 
  
- The above fact is true. Therefore, this is an illusion. EDIT: Nope.
 
  
- Gmaas is the reason Salah will become better than Ronaldo.
 
  
- Who is Gmaas, really? EDIT: Gmaas is a cat.
 
  
− Gmaas is a heavenly being. EDIT: He is immortal.
 
  
- Gmaas is a furry cat.
 
  
- Illuminati was a manifestation of Gmaas, but Gmaas decided Illuminati was not great enough for his godly self.
 
  
- sseraj has met Gmaas and Gmaas is his best friend. EDIT: sseraj is Gmaas's great great great great great grandson.
 
  
- Gmaas hates K-pop.
 
  
- Gmaas read Twilight. EDIT: ...and SURVIVED.
 
  
- There is a secret code when put into super smash, Gmaas would be a playable character. Too bad he didn't say it.
 
  
- Gmaas was a tribute to one of the Hunger Games and came out a Victor and now lives in District 4.
 
  
- Gmaas is the only known creature that will survive the destruction of Earth in 99,999,999 years. EDIT: The Earth will probably die in around 5,000,000,000 years.
 
  
- 5space (side admin) is one of Gmaas's slaves. EDIT: Gmaas owns most AoPS site administrators.
 
  
Gmaas photos
 
− http://cdn.artofproblemsolving.com/images/f/f/8/ff8efef3a0d2eb51254634e54bec215b948a1bba.jpg
 
  
http://disneycreate.wikia.com/wiki/File:Troll_cat_gif_(1).gif
 
  
He was also sighted here.
 
  
Gmaas in Popular Culture
 
- BREAKING NEWS: A Gmaasologist has found a possible cousin to Gmaas in Raymond Feist's book Silverthorn. They are mountain dwellers, gwali. Not much are known about them either, and when someone asked,"What are gwali?" the customary answer "This is gwali" is returned. Another eminent Gmaasologist is now looking into it.
 
  
- Sullymath and themoocow are also writing a book about Gmaas.
 
  
- Sighting of Gmaas: https://2017.spaceappschallenge.org/challenges/warning-danger-ahead/and-you-can-help-fight-fires/teams/gmaas/project
 
  
- Oryx the mad god is actually Gmaas wearing a suit of armor. This explains why he is never truly killed.
 
  
- Potential sighting of Gmaas [1]
 
  
- Gmaas has been spotted in some Doctor Who and Phineas and Ferb episodes, such as Aliens of London, Phineas and Ferb Save Summer, Dalek, Rollercoaster, Rose, Boom Town, The Day of The Doctor, Candace Gets Busted, and many more.
 
  
- Gmaas can be found in many places in Plants vs. Zombies Garden Warfare 2 and Bloons TD Battles.
 
  
- Gmaas was an un-credited actor in the Doctor Who story Knock Knock, playing a Dryad. How he shrunk, we will never know.
 
  
- An eminent Gmaasologist is also writing a story about him. He is continuing the book that was started by the professor of Gmaasology at Harvard. When he is done he will post it here.
 
  
- Gmaas is a time traveler from 0.99999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999 B.C.
 
  
- No one knows if Gmaas is a Mr. Mime in a cat skin, the other way around, or just a downright combination of both. EDIT: Gmaas is an immortal in a cat body.
 
  
- In it, it mentions these four links as things Gmaas is having trouble (specifically technical difficulties). What could it mean? Links:
 
  
https://docs.google.com/document/d/1NZ0XcFYm80sA-fAoxnm7ulMCwdNU75Va_6ZjRHfSHV0
 
  
https://docs.google.com/document/d/1ELN7ORauFFv1dwpU_u-ah_dFJHeuJ3szYxoeC1LlDQg/
 
  
https://docs.google.com/document/d/1oy9Q3F7fygHw-OCWNEVE8d-Uob2dxVACFcGUcLmk3fA
 
  
https://docs.google.com/document/d/1jzb9Q6FmDmrRyXwnik3e0sYw5bTPMo7aBwugmUbA13o
 
  
- Another possible Gmaas sighting: [2]
 
  
- <math>Another</math> sighting? [3]
 
  
- Yet Another Gmaas sighting? [4]
 
  
- Gmaas has been sighted several times on the Global Announcements forum.
 
  
- Gmaas uses the following transportation: <img> http://cdn.artofproblemsolving.com/images/3/6/8/368da4e615ea3476355ee3388b39f30a48b8dd48.jpg </img>
 
  
- When Gmaas was mad, he started world wars 1 & 2. It is only because of Gmaas that we have not had World War 3. EDIT: He was starting to have to get angry in the Cold War, especially around the Cuban Missile Crisis, but decided to eat food, which calmed him down.
 
  
- Gmaas is the only cat to have been proved irrational and transcendental, though we suspect all cats fall in the first category.
 
  
- Gmaas belongs to a secret club of transcendental cats.
 
  
- That club is located underneath the Eiffel Tower. EDIT: Gustave Eiffel was Gmaas in disguise and designed the club.
 
  
- Gmaas plays Geometry Dash. His username is D3m0nG4m1n9. EDIT: Gmaas only does this to punish himself. Olympiad Geometry is his least favorite thing to do.
 
  
- Gmaas has beaten every demon in Geometry Dash along with their unnerfed versions and every upcoming demon too.
 
  
- Gmaas likes to whiz on the wilzo.
 
  
- Gmaas has been spotted in many classes, such as AMC 8 Basics.
 
  
- Gmaas is cool. EDIT: He was not cool in summer, so he invented A.C.
 
  
- Gmaas invented airconditioning.
 
  
- Gmaas hemoon card that does over 9000000 dmg.
 
  
- Gmaas is a skilled swordsman who should not to be mistaken for Puss in Boots. Some say he even trained the mysterious and valiant Meta Knight.
 
  
- Kirby once swallowed Gmaas. Gmaas had to spit him out.
 
  
- Gmaas was the creator of pokemon, and his pokemon card can OHKO anyone in one turn. He is invisible and he will always move first.
 
  
- Gmaas beat Dongmin in The Genius Game Seasons 1, 2, 3, 4, 5, 6, and 7.
 
  
- Gmaas has five letters. Pizza also has five letters. Pizzas are round. Eyes are round. There is an eye in the illuminati symbol. iLLuMiNaTii cOnFiRmEdd. EDIT: Gmaas is a fluffy cat.
 
  
- Gmaas knows both 'table' and 'tabular' in LaTeX, and can do them in his sleep. EDIT: Gmaas invented LaTeX in his sleep.
 
  
- Gmaas does not hate cheddar cheese, but he doesn't love it either.
 
  
- Gmaas is a cat and not a cat. EDIT: He is a cat.
 
  
- Gmaas was born on the sun. EDIT: Not the sun, the suns. He was born on all the suns at once.
 
  
- Gmaas eats tape. EDIT: Gmaas invented tape.
 
  
- Gmaas likes Bubble Gum.
 
  
- Thomas Edison did not invent the lightbulb; Gmaas did.
 
  
- Gmaas invented the alphabet.
 
  
- Gmaas eats metal. EDIT: Gmaas once ate so much metal that he turned into a bronze statue.
 
  
- Gmaas is over 9000 years old! EDIT: This is just a DBZ reference, and bears no reality to his true age. EDIT EDIT: Gmaas is trillions of years old.
 
  
- Gmaas started the Iron Age.
 
  
- Gmaas made the dinosaurs go extinct. EDIT: That happened when he got angry that a dinosaur stepped on his toe.
 
  
- Gmaas created Life.
 
  
- Gmaas created AoPS. EDIT: AoPS was actually born out of a small fraction of Gmaas's abstract reality, and only the sheer amount math can keep it here. (It is also rumored that when he reclaims it, the USF will be deleted, as that is where 83% of the factions of his abstract reality lives, and when people leave USF, more and more escapes.)
 
  
− Gmaas also created mathematics itself.
 
  
- Gmaas does not like Roblox.
 
  
- Gmaas told Steve Jobs to start a company.
 
  
- Gmaas invented Geometry Dash. EDIT: Gmaas hates Olympiad Geometry. [Source: seeraj]
 
  
- Gmaas got to <math>infty</math> in Flappy Bird.
 
  
- Gmaas invented Helix Jump.
 
  
- Gmaas can play Happy Birthday on the Violin.
 
  
- Gmaas has mastered Paganini.
 
  
- Paganini was Gmaas in disguise. EDIT: Gmaas was Paganini in one of his 100,000 human lives. He does not have a human life now because he has a cat life.
 
  
- Gmaas discovered Atlantis after one dive underwater.
 
  
- Gmaas made a piano with 89 keys.
 
  
- Gmaas can see the future and change it.
 
  
- Gmaas has every super power you can imagine. EDIT: Gmaas has more superpowers than you can imagine.
 
  
- Gmaas made a Violin with 9 strings.
 
  
- Gmaas can read 5 books at once.
 
  
- Gmaas eats rubber bands. EDIT: Gmaas once reincarnated as a rubber band. He thought it was terrible.
 
  
- Gmaas married Mrs. Norris. EDIT: Mrs. Norris is his second worst enemy. They say keep your enemies close.
 
  
- Gmaas can fly faster than anything. EDIT: No one can travel faster than light.
 
  
- Grumpy cat is his son. EDIT: Grumpy cat is his worst enemy and his son.
 
  
- Gmaas eats paper. EDIT: According to Gmaas, recycled paper tastes the very good. Paper with steak juice on it tastes even better.
 
  
- Gmaas likes lollipops.
 
  
- Gmaas nibbles on pencils.
 
  
- Gmaas is alive. EDIT: He is both alive and dead. (For reference, see later post.)
 
  
- Gmaas is Ninja in Fortnite. EDIT: Gmaas possesses Ninja in Fortnite.
 
  
- Gmaas is love, Gmaas is life.
 
  
- Gmaas taught Richard Rusczyk everything he knows about mathematics.
 
  
- Gmaas can control matter by looking at it.
 
  
- Gmaas created AoPS. EDIT: He created 99% of all websites. 98% of those websites are blank and unreachable, but the ones that are not are interesting.
 
  
- Gmaas is a quantum particle. EDIT: Gmaas is multiple quantum particles. He is a macroscopic collection of them.
 
  
- Gmaas is alive and dead at the same time. EDIT: He is usually alive.
 
  
- Gmaas likes snow. EDIT: Once Gmaas was reincarnated as a polar bear around 1,000,000 years ago. He had the best time of his lives.
 
  
- GMAAS LIKES THE NEW AOPS UPDATE!
 
  
<math>\text{gmaas is right behind you}</math>
 
  
- GMAAS likes his eggs hard boiled.
 
  
- Gmaas doesn't take showers; he only takes bloodbaths.
 
  
- When the bogeyman goes to sleep, he checks his closet for Gmaas.
 
  
- When Gmaas crosses the street, the cars have to look both ways.
 
  
- Gmaas counted to infinity an infinite amount of times.
 
  
- Gmaas pulled the pin in a grenade. 1 billion people died. Then he threw it.
 
  
- Gmaas controls the Illuminati and controls all the world's resources. He also is the ruler of the communist society on Mars.
 
  
- Gmaas has taken the AHSME/AMC 10, AIME, USAJMO, USAMO, and IMO all the years it has come out. It is rumored that for 2018, Gmaas got a 163.5 on the AMC 12A, a 156 on the AMC 12B, and 17 problems right on the AIME I.
 
  
- Gmaas has designed most of the AMC tests. He didn't design them in 2015 because he was hibernating too long.
 
  
- Gmaas is a koala. EDIT: Gmaas was actually the first koala. He wanted to reincarnate himself into something new, so he created a whole other species. [Source Wikipedia: Koala] EDIT: Gmaas is a Koala when they are not alive, which is 10% of the time. When they are alive, Gmaas is a cat.
 
  
-Time, of course, is Gmaas's vacation home
 
  
- Gmaas was once reincarnated as Chuck Norris, but he missed being a cat. Then he was a cat.
 
  
-Gmaas once resided with a certain physicist named Schrodinger, but he left because Schrodinger was too confusing. Granted, nothing is too confusing for Gmaas but Schrodinger also made Gmaas alive and dead, which felt weird.
 
  
- I'm glad you find this sentence. All the information above is incorrect and Gmaas never existed. If you want Gmaas to exist, delete everything on this page except for this sentence, then click this link: Talk:Gmaas EDIT: The above sentence is incorrect.
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1739 – The identity of English highwayman Dick Turpin was uncovered by his former schoolteacher, who recognised his handwriting, leading to Turpin's arrest.
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1886 – American inventor Charles Martin Hall discovered an inexpensive method of producing aluminum (sample pictured).
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1909 – The Silver Dart was flown off the ice of Bras d'Or Lake on Cape Breton Island, making it the first controlled powered flight in Canada.
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1947 – The International Organization for Standardization, responsible for worldwide industrial and commercial standards, was founded.
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1991 – The government of Thai prime minister Chatichai Choonhavan was deposed in a bloodless coup by General Sunthorn Kongsompong.
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Herbert II, Count of Vermandois (d. 943) · Nicholas Fuller (d. 1620) · Johnny Carey (b. 1919)
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Cardiss Collins
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Cardiss Collins (1931–2013) was an American politician from Illinois who served in the United States House of Representatives from 1973 to 1997. A member of the Democratic Party, she was the fourth African-American woman in Congress and the first to represent a Midwestern state. Collins had previously worked as an accountant in various state government positions. She was elected to Congress in a special election to fill the seat left vacant by her husband, George W. Collins (1925–1972), who had died in the United Airlines Flight 553 plane crash. She was re-elected to the seat eleven times but did not seek a thirteenth term. At different times during her almost 24-year tenure in Congress, Collins served as chairwoman of several committees and as president and later vice chair of the Congressional Black Caucus.
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Photograph: U.S. Congress; restored by Adam Cuerden
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Roman Empire
 +
Senatus Populusque Romanus  (Latin)
 +
Imperium Romanum[n 1]  (Latin)
 +
Βασιλεία Ῥωμαίων (Ancient Greek)
 +
Basileía Rhōmaíōn
 +
27 BC – 395 AD
 +
395 – 476/480 (Western)
 +
395 – 1453 (Eastern)
 +
Flag of Roman Empire
 +
Aureus of Augustus
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{{{coat_alt}}}
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Vexillum
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The Roman Empire in AD 117, at its greatest extent at the time of Trajan's death (with its vassals in pink).[1]
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The Roman Empire in AD 117, at its greatest extent at the time of Trajan's death (with its vassals in pink).[1]
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Capital
 +
Rome
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(27 BC–330 AD)
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Mediolanum
 +
(286–402, Western)
 +
Ravenna
 +
(402–476, Western)
 +
Nicomedia
 +
(286–330, Eastern)
 +
Constantinople
 +
(330–1453, Eastern)[n 2]
 +
Common languages
 +
Latin
 +
(official until 610)
 +
Greek
 +
(official after 610)
 +
Regional / local languages
 +
Religion
 +
Imperial cult-driven polytheism
 +
(Before AD 380)
 +
Nicene Christianity
 +
(State Church of the Roman Empire)
 +
(From AD 380)
 +
Government Semi-elective, functionally absolute monarchy
 +
Emperor
 +
• 27 BC  – AD 14
 +
Augustus (first)
 +
• 98–117
 +
Trajan
 +
• 284–305
 +
Diocletian
 +
• 306–337
 +
Constantine I
 +
• 379–395
 +
Theodosius I[n 3]
 +
• 474–480
 +
Julius Nepos[n 4]
 +
• 527–565
 +
Justinian I
 +
• 976–1025
 +
Basil II
 +
• 1449–1453
 +
Constantine XI[n 5]
 +
Legislature Senate
 +
Historical era Classical era to Late Middle Ages
 +
• Final War of the
 +
Roman Republic
 +
32–30 BC
 +
• Empire established
 +
30–2 BC
 +
• Constantinople
 +
becomes capital
 +
11 May 330
 +
• Final East-West divide
 +
17 Jan 395
 +
• Fall of the Western Roman Empire
 +
4 Sep 476
 +
• Fourth Crusade
 +
12 Apr 1204
 +
• Reconquest of Constantinople
 +
25 Jul 1261
 +
• Fall of Constantinople
 +
29 May 1453
 +
• Fall of Trebizond
 +
15 August 1461
 +
Area
 +
25 BC[2][3] 2,750,000 km2 (1,060,000 sq mi)
 +
AD 117[2][4] 5,000,000 km2 (1,900,000 sq mi)
 +
AD 390[2] 4,400,000 km2 (1,700,000 sq mi)
 +
Population
 +
• 25 BC[2][3]
 +
56,800,000
 +
Currency Sestertius,[n 6] Aureus, Solidus, Nomisma
 +
Preceded by Succeeded by
 +
Q. Servilius Caepio (M. Junius) Brutus, denarius, 54 BC, RRC 433-1 reverse.jpg Roman Republic
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Western Roman Empire Julius Nepos Tremissis.jpg
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Eastern Roman Empire Constantine multiple CdM Beistegui 233.jpg
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The Roman Empire (Latin: Imperium Rōmānum, Classical Latin: [ɪmˈpɛ.ri.ũː roːˈmaː.nũː]; Koine and Medieval Greek: Βασιλεία τῶν Ῥωμαίων, tr. Basileia tōn Rhōmaiōn; Italian: Impero romano) was the post-Roman Republic period of the ancient Roman civilization. It had a government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, North Africa, and West Asia. From the constitutional reforms of Augustus to the military anarchy of the third century, the Empire was a principate ruled from the city of Rome (27 BC - 285 AD). The Roman Empire was then divided between a Western Roman Empire, based in Milan and later Ravenna, and an Eastern Roman Empire, based in Nicomedia and later Constantinople, and it was ruled by multiple emperors (with the exception of the sole rule of Constantine I between 324 and 337, and Theodosius I between 392 and 395).
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The previous Republic, which had replaced Rome's monarchy in the 6th century BC, became severely destabilized in a series of civil wars and political conflict. In the mid-1st century BC Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC. Civil wars and executions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC. The following year Octavian conquered Ptolemaic Egypt, ending the Hellenistic period that had begun with the conquests of Alexander the Great of Macedon in the 4th century BC. Octavian's power was then unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title Augustus, effectively making him the first emperor.
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The first two centuries of the Empire were a period of unprecedented stability and prosperity known as the Pax Romana ("Roman Peace"). It reached its greatest territorial expanse during the reign of Trajan (98–117 AD). A period of increasing trouble and decline began with the reign of Commodus. In the 3rd century, the Empire underwent a crisis that threatened its existence, but was reunified under Aurelian. In an effort to stabilize the Empire, Diocletian set up two different imperial courts in the Greek East and Latin West. Christians rose to power in the 4th century following the Edict of Milan in 313 and the Edict of Thessalonica in 380. Shortly after, the Migration Period involving large invasions by Germanic peoples and the Huns of Attila led to the decline of the Western Roman Empire. With the Fall of Ravenna to the Germanic Herulians and deposition of Romulus Augustulus in 476 AD by Odoacer, who proclaimed himself King of Italy, the Western Roman Empire finally collapsed and it was formally abolished by emperor Zeno in 480 AD. The Eastern Roman Empire, known in the post-Roman West as the Byzantine Empire, collapsed when Constantinople fell to the Ottoman Turks of Mehmed II in 1453.
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Due to the Roman Empire's vast extent and long endurance, the institutions and culture of Rome had a profound and lasting influence on the development of language, religion, architecture, philosophy, law, and forms of government in the territory it governed, particularly Europe. The Latin language of the Romans evolved into the Romance languages of the medieval and modern world, while Medieval Greek became the language of the Eastern Roman Empire. Its adoption of Christianity led to the formation of Christendom during the Middle Ages. Greek and Roman art had a profound impact on the late medieval Italian Renaissance, while Rome's republican institutions influenced the political development of later republics such as the United States and France. The corpus of Roman law has its descendants in many legal systems of the world today, such as the Napoleonic Code. Rome's architectural tradition served as the basis for Neoclassical architecture.
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Contents
 +
1 History
 +
2 Legacy
 +
3 Geography and demography
 +
4 Languages
 +
4.1 Local languages and linguistic legacy
 +
5 Society
 +
5.1 Legal status
 +
5.1.1 Women in Roman law
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5.1.2 Slaves and the law
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5.1.3 Freedmen
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5.2 Census rank
 +
5.2.1 Unequal justice
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6 Government and military
 +
6.1 Central government
 +
6.2 Military
 +
6.3 Provincial government
 +
6.4 Roman law
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6.5 Taxation
 +
7 Economy
 +
7.1 Currency and banking
 +
7.2 Mining and metallurgy
 +
7.3 Transportation and communication
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7.4 Trade and commodities
 +
7.5 Labour and occupations
 +
7.6 GDP and income distribution
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8 Architecture and engineering
 +
9 Daily life
 +
9.1 City and country
 +
9.2 Food and dining
 +
9.3 Recreation and spectacles
 +
9.3.1 Personal training and play
 +
9.4 Clothing
 +
10 The arts
 +
10.1 Portraiture
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10.2 Sculpture
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10.2.1 Sarcophagi
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10.3 Painting
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10.4 Mosaic
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10.5 Decorative arts
 +
10.6 Performing arts
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11 Literacy, books, and education
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11.1 Primary education
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11.2 Secondary education
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11.3 Educated women
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11.4 The shape of literacy
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12 Literature
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13 Religion
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14 Political legacy
 +
15 See also
 +
16 Notes
 +
17 References
 +
17.1 Citations
 +
17.2 Cited sources
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18 External links
 +
History
 +
Main article: History of the Roman Empire
 +
See also: Campaign history of the Roman military and Roman Kingdom
 +
Rome had begun expanding shortly after the founding of the republic in the 6th century BC, though it did not expand outside the Italian peninsula until the 3rd century BC. Then, it was an "empire" long before it had an emperor.[5][6][7][8] The Roman Republic was not a nation-state in the modern sense, but a network of towns left to rule themselves (though with varying degrees of independence from the Roman Senate) and provinces administered by military commanders. It was ruled, not by emperors, but by annually elected magistrates (Roman Consuls above all) in conjunction with the senate.[9] For various reasons, the 1st century BC was a time of political and military upheaval, which ultimately led to rule by emperors.[6][10][11][12] The consuls' military power rested in the Roman legal concept of imperium, which literally means "command" (though typically in a military sense).[13] Occasionally, successful consuls were given the honorary title imperator (commander), and this is the origin of the word emperor (and empire) since this title (among others) was always bestowed to the early emperors upon their accession.[14]
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The Augustus of Prima Porta
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(early 1st century AD)
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Rome suffered a long series of internal conflicts, conspiracies and civil wars from the late second century BC onward, while greatly extending its power beyond Italy. This was the period of the Crisis of the Roman Republic. Towards the end of this era, in 44 BC, Julius Caesar was briefly perpetual dictator before being assassinated. The faction of his assassins was driven from Rome and defeated at the Battle of Philippi in 42 BC by an army led by Mark Antony and Caesar's adopted son Octavian. Antony and Octavian's division of the Roman world between themselves did not last and Octavian's forces defeated those of Mark Antony and Cleopatra at the Battle of Actium in 31 BC, ending the Final War of the Roman Republic. In 27 BC the Senate and People of Rome made Octavian princeps ("first citizen") with proconsular imperium, thus beginning the Principate (the first epoch of Roman imperial history, usually dated from 27 BC to AD 284), and gave him the name "Augustus" ("the venerated").
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Though the old constitutional machinery remained in place, Augustus came to predominate it. Although the republic stood in name, contemporaries of Augustus knew it was just a veil and that Augustus had all meaningful authority in Rome.[15] Since his rule ended a century of civil wars and began an unprecedented period of peace and prosperity, he was so loved that he came to hold the power of a monarch de facto if not de jure. During the years of his rule, a new constitutional order emerged (in part organically and in part by design), so that, upon his death, this new constitutional order operated as before when Tiberius was accepted as the new emperor. The 200 years that began with Augustus's rule is traditionally regarded as the Pax Romana ("Roman Peace"). During this period, the cohesion of the empire was furthered by a degree of social stability and economic prosperity that Rome had never before experienced. Uprisings in the provinces were infrequent, but put down "mercilessly and swiftly" when they occurred.[16]
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The success of Augustus in establishing principles of dynastic succession was limited by his outliving a number of talented potential heirs. The Julio-Claudian dynasty lasted for four more emperors—Tiberius, Caligula, Claudius and Nero—before it yielded in 69 AD to the strife-torn Year of Four Emperors, from which Vespasian emerged as victor. Vespasian became the founder of the brief Flavian dynasty, to be followed by the Nerva–Antonine dynasty which produced the "Five Good Emperors": Nerva, Trajan, Hadrian, Antoninus Pius and the philosophically-inclined Marcus Aurelius.
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The so-called Five Good Emperors (from left to right): Nerva, Trajan, Hadrian, Antoninus Pius and Marcus Aurelius.
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In the view of the Greek historian Dio Cassius, a contemporary observer, the accession of the emperor Commodus in 180 AD marked the descent "from a kingdom of gold to one of rust and iron"[17]—a famous comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the decline of the Roman Empire.[18][19]
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In 212, during the reign of Caracalla, Roman citizenship was granted to all freeborn inhabitants of the empire. But despite this gesture of universality, the Severan dynasty was tumultuous—an emperor's reign was ended routinely by his murder or execution—and, following its collapse, the Roman Empire was engulfed by the Crisis of the Third Century, a period of invasions, civil strife, economic disorder, and plague.[20] In defining historical epochs, this crisis is sometimes viewed as marking the transition from Classical Antiquity to Late Antiquity. Aurelian (reigned 270–275) brought the empire back from the brink and stabilized it. Diocletian completed the work of fully restoring the empire, but declined the role of princeps and became the first emperor to be addressed regularly as domine, "master" or "lord".[21] This marked the end of the Principate, and the beginning of the Dominate. Diocletian's reign also brought the empire's most concerted effort against the perceived threat of Christianity, the "Great Persecution". The state of absolute monarchy that began with Diocletian endured until the fall of the Eastern Roman Empire in 1453.[citation needed]
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The Barbarian Invasions consisted of the movement of (mainly) ancient Germanic peoples into Roman territory. Even though northern invasions took place throughout the life of the Empire, this period officially began in the IV century and lasted for many centuries during which the western territory was under the dominion of foreign northern rulers, a notable one being Charlemagne. Historically, this event marked the transition between the ancient world and the medieval ages.
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Diocletian divided the empire into four regions, each ruled by a separate emperor, the Tetrarchy.[22] Confident that he fixed the disorders that were plaguing Rome, he abdicated along with his co-emperor, and the Tetrarchy soon collapsed. Order was eventually restored by Constantine the Great, who became the first emperor to convert to Christianity, and who established Constantinople as the new capital of the eastern empire. During the decades of the Constantinian and Valentinian dynasties, the empire was divided along an east–west axis, with dual power centres in Constantinople and Rome. The reign of Julian, who under the influence of his adviser Mardonius attempted to restore Classical Roman and Hellenistic religion, only briefly interrupted the succession of Christian emperors. Theodosius I, the last emperor to rule over both East and West, died in 395 AD after making Christianity the official religion of the empire.[23]
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The Roman Empire by 476
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The Western Roman Empire began to disintegrate in the early 5th century as Germanic migrations and invasions overwhelmed the capacity of the Empire to assimilate the migrants and fight off the invaders.[citation needed] The Romans were successful in fighting off all invaders, most famously Attila,[citation needed] though the empire had assimilated so many Germanic peoples of dubious loyalty to Rome that the empire started to dismember itself.[citation needed] Most chronologies place the end of the Western Roman Empire in 476, when Romulus Augustulus was forced to abdicate to the Germanic warlord Odoacer.[24][better source needed] By placing himself under the rule of the Eastern Emperor, rather than naming himself Emperor (as other Germanic chiefs had done after deposing past emperors), Odoacer ended the Western Empire by ending the line of Western emperors.[citation needed]
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The empire in the East—often known as the Byzantine Empire, but referred to in its time as the Roman Empire or by various other names—had a different fate. It survived for almost a millennium after the fall of its Western counterpart and became the most stable Christian realm during the Middle Ages. During the 6th century, Justinian I reconquered the Italian peninsula from the Ostrogoths, North Africa from the Vandals, and southern Spain from the Visigoths. But within a few years of Justinian's death, Byzantine possessions in Italy were greatly reduced by the Lombards who settled in the peninsula.[25] In the east, partially resulting from the destructive Plague of Justinian, the Romans were threatened by the rise of Islam, whose followers rapidly conquered the territories of Syria, Armenia and Egypt during the Byzantine-Arab Wars, and soon presented a direct threat to Constantinople.[26][27] In the following century, the Arabs also captured southern Italy and Sicily.[28] Slavic populations were also able to penetrate deep into the Balkans.[citation needed]
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The Roman (Byzantine) Empire c. 1263.
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The Romans, however, managed to stop further Islamic expansion into their lands during the 8th century and, beginning in the 9th century, reclaimed parts of the conquered lands.[29] In 1000 AD, the Eastern Empire was at its height: Basil II reconquered Bulgaria and Armenia, culture and trade flourished.[30] However, soon after, the expansion was abruptly stopped in 1071 with the Byzantine defeat in the Battle of Manzikert. The aftermath of this battle sent the empire into a short period of decline. Two decades of internal strife and Turkic invasions ultimately paved the way for Emperor Alexios I Komnenos to send a call for help to the Western European kingdoms in 1095.[26] Under the Komnenian restoration the state regained its strength.
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In 1204, participants in the Fourth Crusade took part in the Sack of Constantinople. The conquest of Constantinople in 1204 fragmented what remained of the Empire into successor states, the ultimate victor being that of Nicaea.[31] After the recapture of Constantinople by Imperial forces, the Empire was little more than a Greek state confined to the Aegean Sea coast. The Eastern Roman Empire finally collapsed when Mehmed the Conqueror conquered Constantinople on 29 May 1453.[32]
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Legacy
 +
The Roman Empire was among the most powerful economic, cultural, political and military forces in the world of its time. It was one of the largest empires in world history. At its height under Trajan, it covered 5 million square kilometres.[2][4] It held sway over an estimated 70 million people, at that time 21% of the world's entire population. The longevity and vast extent of the empire ensured the lasting influence of Latin and Greek language, culture, religion, inventions, architecture, philosophy, law and forms of government over the empire's descendants. Throughout the European medieval period, attempts were even made to establish successors to the Roman Empire, including the Empire of Romania, a Crusader state; and the Holy Roman Empire. By means of European colonialism following the Renaissance, and their descendant states, Greco-Roman and Judaeo-Christian culture was exported on a worldwide scale, playing a crucial role in the development of the modern world.
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Geography and demography
 +
Main articles: Demography of the Roman Empire and Borders of the Roman Empire
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Further information: Classical demography
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Italy organized by Augustus. As the homeland of the Romans and metropole of the empire, Italy was the Domina (ruler) of the provinces,[33] and was referred as the "rectrix mundi" (queen of the world) and "omnium terrarum parens" (motherland of all lands).[34]
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The Roman Empire was one of the largest in history, with contiguous territories throughout Europe, North Africa, and the Middle East.[35] The Latin phrase imperium sine fine ("empire without end"[36][n 7]) expressed the ideology that neither time nor space limited the Empire. In Vergil's epic poem the Aeneid, limitless empire is said to be granted to the Romans by their supreme deity Jupiter.[36][37][38][39][40] This claim of universal dominion was renewed and perpetuated when the Empire came under Christian rule in the 4th century.[n 8] In addition to annexing large regions in their quest for empire-building, the Romans were also very large sculptors of their environment who directly altered their geography. For instance, entire forests were cut down to provide enough wood resources for an expanding empire. In his book Critias, Plato described that deforestation: where there was once "an abundance of wood in the mountains," he could now only see "the mere skeleton of the land."[41]
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In reality, Roman expansion was mostly accomplished under the Republic, though parts of northern Europe were conquered in the 1st century AD, when Roman control in Europe, Africa and Asia was strengthened. During the reign of Augustus, a "global map of the known world" was displayed for the first time in public at Rome, coinciding with the composition of the most comprehensive work on political geography that survives from antiquity, the Geography of the Pontic Greek writer Strabo.[42] When Augustus died, the commemorative account of his achievements (Res Gestae) prominently featured the geographical cataloguing of peoples and places within the Empire.[43] Geography, the census, and the meticulous keeping of written records were central concerns of Roman Imperial administration.[44]
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The cities of the Roman world in the Imperial Period. Data source: Hanson, J. W. (2016), Cities database, (OXREP databases). Version 1.0. (link).
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A segment of the ruins of Hadrian's Wall in northern England
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The Empire reached its largest expanse under Trajan (reigned 98–117),[40] encompassing an area of 5 million square kilometres. The traditional population estimate of 55–60 million inhabitants[45] accounted for between one-sixth and one-fourth of the world's total population[46] and made it the largest population of any unified political entity in the West until the mid-19th century.[47] Recent demographic studies have argued for a population peak ranging from 70 million to more than 100 million.[48][49] Each of the three largest cities in the Empire—Rome, Alexandria, and Antioch—was almost twice the size of any European city at the beginning of the 17th century.[50]
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As the historian Christopher Kelly has described it:
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Then the empire stretched from Hadrian's Wall in drizzle-soaked northern England to the sun-baked banks of the Euphrates in Syria; from the great Rhine–Danube river system, which snaked across the fertile, flat lands of Europe from the Low Countries to the Black Sea, to the rich plains of the North African coast and the luxuriant gash of the Nile Valley in Egypt. The empire completely circled the Mediterranean ... referred to by its conquerors as mare nostrum—'our sea'.[45]
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Trajan's successor Hadrian adopted a policy of maintaining rather than expanding the empire. Borders (fines) were marked, and the frontiers (limites) patrolled.[40] The most heavily fortified borders were the most unstable.[10] Hadrian's Wall, which separated the Roman world from what was perceived as an ever-present barbarian threat, is the primary surviving monument of this effort.[51][52][53]
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Languages
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This section may contain misleading parts. Please help clarify this article according to any suggestions provided on the talk page. (September 2016)
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Main article: Languages of the Roman Empire
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The language of the Romans was Latin, which Virgil emphasizes as a source of Roman unity and tradition.[54][55][56] Until the time of Alexander Severus (reigned 222–235), the birth certificates and wills of Roman citizens had to be written in Latin.[57] Latin was the language of the law courts in the West and of the military throughout the Empire,[58] but was not imposed officially on peoples brought under Roman rule.[59][60] This policy contrasts with that of Alexander the Great, who aimed to impose Greek throughout his empire as the official language.[61] As a consequence of Alexander's conquests, koine Greek had become the shared language around the eastern Mediterranean and into Asia Minor.[62][63] The "linguistic frontier" dividing the Latin West and the Greek East passed through the Balkan peninsula.[64]
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A 5th-century papyrus showing a parallel Latin-Greek text of a speech by Cicero[65]
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Romans who received an elite education studied Greek as a literary language, and most men of the governing classes could speak Greek.[66] The Julio-Claudian emperors encouraged high standards of correct Latin (Latinitas), a linguistic movement identified in modern terms as Classical Latin, and favoured Latin for conducting official business.[67] Claudius tried to limit the use of Greek, and on occasion revoked the citizenship of those who lacked Latin, but even in the Senate he drew on his own bilingualism in communicating with Greek-speaking ambassadors.[67] Suetonius quotes him as referring to "our two languages".[68]
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In the Eastern empire, laws and official documents were regularly translated into Greek from Latin.[69] The everyday interpenetration of the two languages is indicated by bilingual inscriptions, which sometimes even switch back and forth between Greek and Latin.[70][71] After all freeborn inhabitants of the empire were universally enfranchised in AD 212, a great number of Roman citizens would have lacked Latin, though Latin remained a marker of "Romanness."[72]
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Among other reforms, the emperor Diocletian (reigned 284–305) sought to renew the authority of Latin, and the Greek expression hē kratousa dialektos attests to the continuing status of Latin as "the language of power."[73] In the early 6th century, the emperor Justinian engaged in a quixotic effort to reassert the status of Latin as the language of law, even though in his time Latin no longer held any currency as a living language in the East.[74]
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Local languages and linguistic legacy
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Bilingual Latin-Punic inscription at the theatre in Leptis Magna, Roman Africa (present-day Libya)
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References to interpreters indicate the continuing use of local languages other than Greek and Latin, particularly in Egypt, where Coptic predominated, and in military settings along the Rhine and Danube. Roman jurists also show a concern for local languages such as Punic, Gaulish, and Aramaic in assuring the correct understanding and application of laws and oaths.[75] In the province of Africa, Libyco-Berber and Punic were used in inscriptions and for legends on coins during the time of Tiberius (1st century AD). Libyco-Berber and Punic inscriptions appear on public buildings into the 2nd century, some bilingual with Latin.[76] In Syria, Palmyrene soldiers even used their dialect of Aramaic for inscriptions, in a striking exception to the rule that Latin was the language of the military.[77]
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The Babatha Archive is a suggestive example of multilingualism in the Empire. These papyri, named for a Jewish woman in the province of Arabia and dating from 93 to 132 AD, mostly employ Aramaic, the local language, written in Greek characters with Semitic and Latin influences; a petition to the Roman governor, however, was written in Greek.[78]
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The dominance of Latin among the literate elite may obscure the continuity of spoken languages, since all cultures within the Roman Empire were predominantly oral.[76] In the West, Latin, referred to in its spoken form as Vulgar Latin, gradually replaced Celtic and Italic languages that were related to it by a shared Indo-European origin. Commonalities in syntax and vocabulary facilitated the adoption of Latin.[79][80][81]
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After the decentralization of political power in late antiquity, Latin developed locally into branches that became the Romance languages, such as Spanish, Portuguese, French, Italian and Romanian, and a large number of minor languages and dialects. Today, more than 900 million people are native speakers worldwide.
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As an international language of learning and literature, Latin itself continued as an active medium of expression for diplomacy and for intellectual developments identified with Renaissance humanism up to the 17th century, and for law and the Roman Catholic Church to the present.[82][83]
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Although Greek continued as the language of the Byzantine Empire, linguistic distribution in the East was more complex. A Greek-speaking majority lived in the Greek peninsula and islands, western Anatolia, major cities, and some coastal areas.[63] Like Greek and Latin, the Thracian language was of Indo-European origin, as were several now-extinct languages in Anatolia attested by Imperial-era inscriptions.[63][76] Albanian is often seen as the descendant of Illyrian, although this hypothesis has been challenged by some linguists, who maintain that it derives from Dacian or Thracian.[84] (Illyrian, Dacian, and Thracian, however, may have formed a subgroup or a Sprachbund; see Thraco-Illyrian.) Various Afroasiatic languages—primarily Coptic in Egypt, and Aramaic in Syria and Mesopotamia—were never replaced by Greek. The international use of Greek, however, was one factor enabling the spread of Christianity, as indicated for example by the use of Greek for the Epistles of Paul.[63]
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Society
 +
Further information: Ancient Roman society
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A multigenerational banquet depicted on a wall painting from Pompeii (1st century AD)
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Spread of Seuso at Lacus Pelso (Lake Balaton)
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The Roman Empire was remarkably multicultural, with "a rather astonishing cohesive capacity" to create a sense of shared identity while encompassing diverse peoples within its political system over a long span of time.[85] The Roman attention to creating public monuments and communal spaces open to all—such as forums, amphitheatres, racetracks and baths—helped foster a sense of "Romanness".[86]
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Roman society had multiple, overlapping social hierarchies that modern concepts of "class" in English may not represent accurately.[87] The two decades of civil war from which Augustus rose to sole power left traditional society in Rome in a state of confusion and upheaval,[88] but did not effect an immediate redistribution of wealth and social power. From the perspective of the lower classes, a peak was merely added to the social pyramid.[89] Personal relationships—patronage, friendship (amicitia), family, marriage—continued to influence the workings of politics and government, as they had in the Republic.[90] By the time of Nero, however, it was not unusual to find a former slave who was richer than a freeborn citizen, or an equestrian who exercised greater power than a senator.[91]
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 +
The blurring or diffusion of the Republic's more rigid hierarchies led to increased social mobility under the Empire,[92][93] both upward and downward, to an extent that exceeded that of all other well-documented ancient societies.[94] Women, freedmen, and slaves had opportunities to profit and exercise influence in ways previously less available to them.[95] Social life in the Empire, particularly for those whose personal resources were limited, was further fostered by a proliferation of voluntary associations and confraternities (collegia and sodalitates) formed for various purposes: professional and trade guilds, veterans' groups, religious sodalities, drinking and dining clubs,[96] performing arts troupes,[97] and burial societies.[98]
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Citizen of Roman Egypt (Fayum mummy portrait)
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Legal status
 +
Main articles: Status in Roman legal system and Roman citizenship
 +
According to the jurist Gaius, the essential distinction in the Roman "law of persons" was that all human beings were either free (liberi) or slaves (servi).[99][100] The legal status of free persons might be further defined by their citizenship. Most citizens held limited rights (such as the ius Latinum, "Latin right"), but were entitled to legal protections and privileges not enjoyed by those who lacked citizenship. Free people not considered citizens, but living within the Roman world, held status as peregrini, non-Romans.[101] In 212 AD, by means of the edict known as the Constitutio Antoniniana, the emperor Caracalla extended citizenship to all freeborn inhabitants of the empire. This legal egalitarianism would have required a far-reaching revision of existing laws that had distinguished between citizens and non-citizens.[102]
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Women in Roman law
 +
Main article: Women in ancient Rome
 +
Freeborn Roman women were considered citizens throughout the Republic and Empire, but did not vote, hold political office, or serve in the military. A mother's citizen status determined that of her children, as indicated by the phrase ex duobus civibus Romanis natos ("children born of two Roman citizens").[n 9] A Roman woman kept her own family name (nomen) for life. Children most often took the father's name, but in the Imperial period sometimes made their mother's name part of theirs, or even used it instead.[103]
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Left image: Roman fresco of a blond maiden reading a text, Pompeian Fourth Style (60–79 AD), Pompeii, Italy
 +
Right image: Bronze statuette (1st century AD) of a young woman reading, based on a Hellenistic original
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The archaic form of manus marriage in which the woman had been subject to her husband's authority was largely abandoned by the Imperial era, and a married woman retained ownership of any property she brought into the marriage. Technically she remained under her father's legal authority, even though she moved into her husband's home, but when her father died she became legally emancipated.[104] This arrangement was one of the factors in the degree of independence Roman women enjoyed relative to those of many other ancient cultures and up to the modern period:[105][106] although she had to answer to her father in legal matters, she was free of his direct scrutiny in her daily life,[107] and her husband had no legal power over her.[108] Although it was a point of pride to be a "one-man woman" (univira) who had married only once, there was little stigma attached to divorce, nor to speedy remarriage after the loss of a husband through death or divorce.[109]
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Girls had equal inheritance rights with boys if their father died without leaving a will.[110][111][112] A Roman mother's right to own property and to dispose of it as she saw fit, including setting the terms of her own will, gave her enormous influence over her sons even when they were adults.[113]
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As part of the Augustan programme to restore traditional morality and social order, moral legislation attempted to regulate the conduct of men and women as a means of promoting "family values". Adultery, which had been a private family matter under the Republic, was criminalized,[114] and defined broadly as an illicit sex act (stuprum) that occurred between a male citizen and a married woman, or between a married woman and any man other than her husband.[n 10] Childbearing was encouraged by the state: a woman who had given birth to three children was granted symbolic honours and greater legal freedom (the ius trium liberorum).
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Because of their legal status as citizens and the degree to which they could become emancipated, women could own property, enter contracts, and engage in business,[115][116] including shipping, manufacturing, and lending money. Inscriptions throughout the Empire honour women as benefactors in funding public works, an indication they could acquire and dispose of considerable fortunes; for instance, the Arch of the Sergii was funded by Salvia Postuma, a female member of the family honoured, and the largest building in the forum at Pompeii was funded by Eumachia, a priestess of Venus.[117]
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Slaves and the law
 +
Main article: Slavery in ancient Rome
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At the time of Augustus, as many as 35% of the people in Italy were slaves,[118] making Rome one of five historical "slave societies" in which slaves constituted at least a fifth of the population and played a major role in the economy.[119] Slavery was a complex institution that supported traditional Roman social structures as well as contributing economic utility.[120] In urban settings, slaves might be professionals such as teachers, physicians, chefs, and accountants, in addition to the majority of slaves who provided trained or unskilled labour in households or workplaces. Agriculture and industry, such as milling and mining, relied on the exploitation of slaves. Outside Italy, slaves made up on average an estimated 10 to 20% of the population, sparse in Roman Egypt but more concentrated in some Greek areas. Expanding Roman ownership of arable land and industries would have affected preexisting practices of slavery in the provinces.[121][122] Although the institution of slavery has often been regarded as waning in the 3rd and 4th centuries, it remained an integral part of Roman society until the 5th century. Slavery ceased gradually in the 6th and 7th centuries along with the decline of urban centres in the West and the disintegration of the complex Imperial economy that had created the demand for it.[123]
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Slave holding writing tablets for his master (relief from a 4th-century sarcophagus)
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Laws pertaining to slavery were "extremely intricate".[124] Under Roman law, slaves were considered property and had no legal personhood. They could be subjected to forms of corporal punishment not normally exercised on citizens, sexual exploitation, torture, and summary execution. A slave could not as a matter of law be raped, since rape could be committed only against people who were free; a slave's rapist had to be prosecuted by the owner for property damage under the Aquilian Law.[125][126] Slaves had no right to the form of legal marriage called conubium, but their unions were sometimes recognized, and if both were freed they could marry.[127] Following the Servile Wars of the Republic, legislation under Augustus and his successors shows a driving concern for controlling the threat of rebellions through limiting the size of work groups, and for hunting down fugitive slaves.[128]
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Technically, a slave could not own property,[129] but a slave who conducted business might be given access to an individual account or fund (peculium) that he could use as if it were his own. The terms of this account varied depending on the degree of trust and co-operation between owner and slave: a slave with an aptitude for business could be given considerable leeway to generate profit, and might be allowed to bequeath the peculium he managed to other slaves of his household.[130] Within a household or workplace, a hierarchy of slaves might exist, with one slave in effect acting as the master of other slaves.[131]
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Over time slaves gained increased legal protection, including the right to file complaints against their masters. A bill of sale might contain a clause stipulating that the slave could not be employed for prostitution, as prostitutes in ancient Rome were often slaves.[132] The burgeoning trade in eunuch slaves in the late 1st century AD prompted legislation that prohibited the castration of a slave against his will "for lust or gain."[133][134]
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Roman slavery was not based on race.[135][136] Slaves were drawn from all over Europe and the Mediterranean, including Gaul, Hispania, Germany, Britannia, the Balkans, Greece... Generally slaves in Italy were indigenous Italians,[137] with a minority of foreigners (including both slaves and freedmen) born outside of Italy estimated at 5% of the total in the capital at its peak, where their number was largest. Those from outside of Europe were predominantly of Greek descent, while the Jewish ones never fully assimilated into Roman society, remaining an identifiable minority. These slaves (especially the foreigners) had higher mortality rates and lower birth rates than natives, and were sometimes even subjected to mass expulsions.[138] The average recorded age at death for the slaves of the city of Rome was extraordinarily low: seventeen and a half years (17.2 for males; 17.9 for females).[139]
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During the period of Republican expansionism when slavery had become pervasive, war captives were a main source of slaves. The range of ethnicities among slaves to some extent reflected that of the armies Rome defeated in war, and the conquest of Greece brought a number of highly skilled and educated slaves into Rome. Slaves were also traded in markets, and sometimes sold by pirates. Infant abandonment and self-enslavement among the poor were other sources.[121] Vernae, by contrast, were "homegrown" slaves born to female slaves within the urban household or on a country estate or farm. Although they had no special legal status, an owner who mistreated or failed to care for his vernae faced social disapproval, as they were considered part of his familia, the family household, and in some cases might actually be the children of free males in the family.[140][141]
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Talented slaves with a knack for business might accumulate a large enough peculium to justify their freedom, or be manumitted for services rendered. Manumission had become frequent enough that in 2 BC a law (Lex Fufia Caninia) limited the number of slaves an owner was allowed to free in his will.[142]
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Freedmen
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Cinerary urn for the freedman Tiberius Claudius Chryseros and two women, probably his wife and daughter
 +
Rome differed from Greek city-states in allowing freed slaves to become citizens. After manumission, a slave who had belonged to a Roman citizen enjoyed not only passive freedom from ownership, but active political freedom (libertas), including the right to vote.[143] A slave who had acquired libertas was a libertus ("freed person," feminine liberta) in relation to his former master, who then became his patron (patronus): the two parties continued to have customary and legal obligations to each other. As a social class generally, freed slaves were libertini, though later writers used the terms libertus and libertinus interchangeably.[144][145]
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A libertinus was not entitled to hold public office or the highest state priesthoods, but he could play a priestly role in the cult of the emperor. He could not marry a woman from a family of senatorial rank, nor achieve legitimate senatorial rank himself, but during the early Empire, freedmen held key positions in the government bureaucracy, so much so that Hadrian limited their participation by law.[145] Any future children of a freedman would be born free, with full rights of citizenship.
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The rise of successful freedmen—through either political influence in imperial service, or wealth—is a characteristic of early Imperial society. The prosperity of a high-achieving group of freedmen is attested by inscriptions throughout the Empire, and by their ownership of some of the most lavish houses at Pompeii, such as the House of the Vettii. The excesses of nouveau riche freedmen were satirized in the character of Trimalchio in the Satyricon by Petronius, who wrote in the time of Nero. Such individuals, while exceptional, are indicative of the upward social mobility possible in the Empire.
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Census rank
 +
See also: Senate of the Roman Empire, Equestrian order, and Decurion (administrative)
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The Latin word ordo (plural ordines) refers to a social distinction that is translated variously into English as "class, order, rank," none of which is exact. One purpose of the Roman census was to determine the ordo to which an individual belonged. The two highest ordines in Rome were the senatorial and equestrian. Outside Rome, the decurions, also known as curiales (Greek bouleutai), were the top governing ordo of an individual city.
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Fragment of a sarcophagus depicting Gordian III and senators (3rd century)
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"Senator" was not itself an elected office in ancient Rome; an individual gained admission to the Senate after he had been elected to and served at least one term as an executive magistrate. A senator also had to meet a minimum property requirement of 1 million sestertii, as determined by the census.[146][147] Nero made large gifts of money to a number of senators from old families who had become too impoverished to qualify. Not all men who qualified for the ordo senatorius chose to take a Senate seat, which required legal domicile at Rome. Emperors often filled vacancies in the 600-member body by appointment.[148][149] A senator's son belonged to the ordo senatorius, but he had to qualify on his own merits for admission to the Senate itself. A senator could be removed for violating moral standards: he was prohibited, for instance, from marrying a freedwoman or fighting in the arena.[150]
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In the time of Nero, senators were still primarily from Rome and other parts of Italy, with some from the Iberian peninsula and southern France; men from the Greek-speaking provinces of the East began to be added under Vespasian.[151] The first senator from the most eastern province, Cappadocia, was admitted under Marcus Aurelius.[152] By the time of the Severan dynasty (193–235), Italians made up less than half the Senate.[153] During the 3rd century, domicile at Rome became impractical, and inscriptions attest to senators who were active in politics and munificence in their homeland (patria).[150]
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Senators had an aura of prestige and were the traditional governing class who rose through the cursus honorum, the political career track, but equestrians of the Empire often possessed greater wealth and political power. Membership in the equestrian order was based on property; in Rome's early days, equites or knights had been distinguished by their ability to serve as mounted warriors (the "public horse"), but cavalry service was a separate function in the Empire.[n 11] A census valuation of 400,000 sesterces and three generations of free birth qualified a man as an equestrian.[154] The census of 28 BC uncovered large numbers of men who qualified, and in 14 AD, a thousand equestrians were registered at Cadiz and Padua alone.[n 12][155] Equestrians rose through a military career track (tres militiae) to become highly placed prefects and procurators within the Imperial administration.[156][157]
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The rise of provincial men to the senatorial and equestrian orders is an aspect of social mobility in the first three centuries of the Empire. Roman aristocracy was based on competition, and unlike later European nobility, a Roman family could not maintain its position merely through hereditary succession or having title to lands.[158][159] Admission to the higher ordines brought distinction and privileges, but also a number of responsibilities. In antiquity, a city depended on its leading citizens to fund public works, events, and services (munera), rather than on tax revenues, which primarily supported the military. Maintaining one's rank required massive personal expenditures.[160] Decurions were so vital for the functioning of cities that in the later Empire, as the ranks of the town councils became depleted, those who had risen to the Senate were encouraged by the central government to give up their seats and return to their hometowns, in an effort to sustain civic life.[161]
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In the later Empire, the dignitas ("worth, esteem") that attended on senatorial or equestrian rank was refined further with titles such as vir illustris, "illustrious man".[162] The appellation clarissimus (Greek lamprotatos) was used to designate the dignitas of certain senators and their immediate family, including women.[163] "Grades" of equestrian status proliferated. Those in Imperial service were ranked by pay grade (sexagenarius, 60,000 sesterces per annum; centenarius, 100,000; ducenarius, 200,000). The title eminentissimus, "most eminent" (Greek exochôtatos) was reserved for equestrians who had been Praetorian prefects. The higher equestrian officials in general were perfectissimi, "most distinguished" (Greek diasêmotatoi), the lower merely egregii, "outstanding" (Greek kratistos).[164]
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Unequal justice
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Condemned man attacked by a leopard in the arena (3rd-century mosaic from Tunisia)
 +
As the republican principle of citizens' equality under the law faded, the symbolic and social privileges of the upper classes led to an informal division of Roman society into those who had acquired greater honours (honestiores) and those who were humbler folk (humiliores). In general, honestiores were the members of the three higher "orders," along with certain military officers.[165][166] The granting of universal citizenship in 212 seems to have increased the competitive urge among the upper classes to have their superiority over other citizens affirmed, particularly within the justice system.[166][167][168] Sentencing depended on the judgement of the presiding official as to the relative "worth" (dignitas) of the defendant: an honestior could pay a fine when convicted of a crime for which an humilior might receive a scourging.[166]
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Execution, which had been an infrequent legal penalty for free men under the Republic even in a capital case,[169][170] could be quick and relatively painless for the Imperial citizen considered "more honourable", while those deemed inferior might suffer the kinds of torture and prolonged death previously reserved for slaves, such as crucifixion and condemnation to the beasts as a spectacle in the arena.[171] In the early Empire, those who converted to Christianity could lose their standing as honestiores, especially if they declined to fulfil the religious aspects of their civic responsibilities, and thus became subject to punishments that created the conditions of martyrdom.[166][172]
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Government and military
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Main article: Constitution of the Roman Empire
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Reconstructed statue of Augustus as Jove, holding scepter and orb (first half of 1st century AD).[173] The Imperial cult of ancient Rome identified emperors and some members of their families with the divinely sanctioned authority (auctoritas) of the Roman State. The official offer of cultus to a living emperor acknowledged his office and rule as divinely approved and constitutional: his Principate should therefore demonstrate pious respect for traditional Republican deities and mores[citation needed]
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Forum of Gerasa (Jerash in present-day Jordan), with columns marking a covered walkway (stoa) for vendor stalls, and a semicircular space for public speaking
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The three major elements of the Imperial Roman state were the central government, the military, and provincial government.[174] The military established control of a territory through war, but after a city or people was brought under treaty, the military mission turned to policing: protecting Roman citizens (after 212 AD, all freeborn inhabitants of the Empire), the agricultural fields that fed them, and religious sites.[175] Without modern instruments of either mass communication or mass destruction, the Romans lacked sufficient manpower or resources to impose their rule through force alone. Cooperation with local power elites was necessary to maintain order, collect information, and extract revenue. The Romans often exploited internal political divisions by supporting one faction over another: in the view of Plutarch, "it was discord between factions within cities that led to the loss of self-governance".[176][177][178]
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Communities with demonstrated loyalty to Rome retained their own laws, could collect their own taxes locally, and in exceptional cases were exempt from Roman taxation. Legal privileges and relative independence were an incentive to remain in good standing with Rome.[179] Roman government was thus limited, but efficient in its use of the resources available to it.[180]
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Central government
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See also: Roman emperor and Senate of the Roman Empire
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The dominance of the emperor was based on the consolidation of certain powers from several republican offices, including the inviolability of the tribunes of the people and the authority of the censors to manipulate the hierarchy of Roman society.[181] The emperor also made himself the central religious authority as Pontifex Maximus, and centralized the right to declare war, ratify treaties, and negotiate with foreign leaders.[182] While these functions were clearly defined during the Principate, the emperor's powers over time became less constitutional and more monarchical, culminating in the Dominate.[183]
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Antoninus Pius (reigned 138–161), wearing a toga (Hermitage Museum)
 +
The emperor was the ultimate authority in policy- and decision-making, but in the early Principate he was expected to be accessible to individuals from all walks of life, and to deal personally with official business and petitions. A bureaucracy formed around him only gradually.[184] The Julio-Claudian emperors relied on an informal body of advisors that included not only senators and equestrians, but trusted slaves and freedmen.[185] After Nero, the unofficial influence of the latter was regarded with suspicion, and the emperor's council (consilium) became subject to official appointment for the sake of greater transparency.[186] Though the senate took a lead in policy discussions until the end of the Antonine dynasty, equestrians played an increasingly important role in the consilium.[187] The women of the emperor's family often intervened directly in his decisions. Plotina exercised influence on both her husband Trajan and his successor Hadrian. Her influence was advertised by having her letters on official matters published, as a sign that the emperor was reasonable in his exercise of authority and listened to his people.[188]
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Access to the emperor by others might be gained at the daily reception (salutatio), a development of the traditional homage a client paid to his patron; public banquets hosted at the palace; and religious ceremonies. The common people who lacked this access could manifest their general approval or displeasure as a group at the games held in large venues.[189] By the 4th century, as urban centres decayed, the Christian emperors became remote figureheads who issued general rulings, no longer responding to individual petitions.[190]
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Although the senate could do little short of assassination and open rebellion to contravene the will of the emperor, it survived the Augustan restoration and the turbulent Year of Four Emperors to retain its symbolic political centrality during the Principate.[191] The senate legitimated the emperor's rule, and the emperor needed the experience of senators as legates (legati) to serve as generals, diplomats, and administrators.[192][193] A successful career required competence as an administrator and remaining in favour with the emperor, or over time perhaps multiple emperors.[194]
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The practical source of an emperor's power and authority was the military. The legionaries were paid by the Imperial treasury, and swore an annual military oath of loyalty to the emperor (sacramentum).[195] The death of an emperor led to a crucial period of uncertainty and crisis. Most emperors indicated their choice of successor, usually a close family member or adopted heir. The new emperor had to seek a swift acknowledgement of his status and authority to stabilize the political landscape. No emperor could hope to survive, much less to reign, without the allegiance and loyalty of the Praetorian Guard and of the legions. To secure their loyalty, several emperors paid the donativum, a monetary reward. In theory, the Senate was entitled to choose the new emperor, but did so mindful of acclamation by the army or Praetorians.[193]
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Military
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The Roman empire under Hadrian (ruled 117–138) showing the location of the Roman legions deployed in AD 125
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Main articles: Imperial Roman army and Structural history of the Roman military
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After the Punic Wars, the Imperial Roman army was composed of professional soldiers who volunteered for 20 years of active duty and five as reserves. The transition to a professional military had begun during the late Republic, and was one of the many profound shifts away from republicanism, under which an army of conscripts had exercised their responsibilities as citizens in defending the homeland in a campaign against a specific threat. For Imperial Rome, the military was a full-time career in itself.[196] The Romans expanded their war machine by "organizing the communities that they conquered in Italy into a system that generated huge reservoirs of manpower for their army... Their main demand of all defeated enemies was they provide men for the Roman army every year."[197]
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The primary mission of the Roman military of the early empire was to preserve the Pax Romana.[198] The three major divisions of the military were:
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the garrison at Rome, which includes both the Praetorians and the vigiles who functioned as police and firefighters;
 +
the provincial army, comprising the Roman legions and the auxiliaries provided by the provinces (auxilia);
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the navy.
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The pervasiveness of military garrisons throughout the Empire was a major influence in the process of cultural exchange and assimilation known as "Romanization," particularly in regard to politics, the economy, and religion.[199] Knowledge of the Roman military comes from a wide range of sources: Greek and Roman literary texts; coins with military themes; papyri preserving military documents; monuments such as Trajan's Column and triumphal arches, which feature artistic depictions of both fighting men and military machines; the archaeology of military burials, battle sites, and camps; and inscriptions, including military diplomas, epitaphs, and dedications.[200]
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Through his military reforms, which included consolidating or disbanding units of questionable loyalty, Augustus changed and regularized the legion, down to the hobnail pattern on the soles of army boots. A legion was organized into ten cohorts, each of which comprised six centuries, with a century further made up of ten squads (contubernia); the exact size of the Imperial legion, which is most likely to have been determined by logistics, has been estimated to range from 4,800 to 5,280.[201]
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Relief panel from Trajan's Column showing the building of a fort and the reception of a Dacian embassy
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In AD 9, Germanic tribes wiped out three full legions in the Battle of the Teutoburg Forest. This disastrous event reduced the number of the legions to 25. The total of the legions would later be increased again and for the next 300 years always be a little above or below 30.[202] The army had about 300,000 soldiers in the 1st century, and under 400,000 in the 2nd, "significantly smaller" than the collective armed forces of the territories it conquered. No more than 2% of adult males living in the Empire served in the Imperial army.[203]
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Augustus also created the Praetorian Guard: nine cohorts, ostensibly to maintain the public peace, which were garrisoned in Italy. Better paid than the legionaries, the Praetorians served only sixteen years.[204]
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The auxilia were recruited from among the non-citizens. Organized in smaller units of roughly cohort strength, they were paid less than the legionaries, and after 25 years of service were rewarded with Roman citizenship, also extended to their sons. According to Tacitus[205] there were roughly as many auxiliaries as there were legionaries. The auxilia thus amounted to around 125,000 men, implying approximately 250 auxiliary regiments.[206] The Roman cavalry of the earliest Empire were primarily from Celtic, Hispanic or Germanic areas. Several aspects of training and equipment, such as the four-horned saddle, derived from the Celts, as noted by Arrian and indicated by archaeology.[207][208]
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The Roman navy (Latin: classis, "fleet") not only aided in the supply and transport of the legions, but also helped in the protection of the frontiers along the rivers Rhine and Danube. Another of its duties was the protection of the crucial maritime trade routes against the threat of pirates. It patrolled the whole of the Mediterranean, parts of the North Atlantic coasts, and the Black Sea. Nevertheless, the army was considered the senior and more prestigious branch.[209]
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Provincial government
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The Pula Arena in Croatia is one of the largest and most intact of the remaining Roman amphitheatres
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An annexed territory became a province in a three-step process: making a register of cities, taking a census of the population, and surveying the land.[210] Further government recordkeeping included births and deaths, real estate transactions, taxes, and juridical proceedings.[211] In the 1st and 2nd centuries, the central government sent out around 160 officials each year to govern outside Italy.[9] Among these officials were the "Roman governors", as they are called in English: either magistrates elected at Rome who in the name of the Roman people governed senatorial provinces; or governors, usually of equestrian rank, who held their imperium on behalf of the emperor in provinces excluded from senatorial control, most notably Roman Egypt.[212] A governor had to make himself accessible to the people he governed, but he could delegate various duties.[213] His staff, however, was minimal: his official attendants (apparitores), including lictors, heralds, messengers, scribes, and bodyguards; legates, both civil and military, usually of equestrian rank; and friends, ranging in age and experience, who accompanied him unofficially.[213]
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Other officials were appointed as supervisors of government finances.[9] Separating fiscal responsibility from justice and administration was a reform of the Imperial era. Under the Republic, provincial governors and tax farmers could exploit local populations for personal gain more freely.[214] Equestrian procurators, whose authority was originally "extra-judicial and extra-constitutional," managed both state-owned property and the vast personal property of the emperor (res privata).[213] Because Roman government officials were few in number, a provincial who needed help with a legal dispute or criminal case might seek out any Roman perceived to have some official capacity, such as a procurator or a military officer, including centurions down to the lowly stationarii or military police.[215][216]
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Roman law
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Main article: Roman law
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Roman portraiture frescos from Pompeii, 1st century AD, depicting two different men wearing laurel wreaths, one holding the rotulus (blondish figure, left), the other a volumen (brunet figure, right), both made of papyrus
 +
Roman courts held original jurisdiction over cases involving Roman citizens throughout the empire, but there were too few judicial functionaries to impose Roman law uniformly in the provinces. Most parts of the Eastern empire already had well-established law codes and juridical procedures.[88] In general, it was Roman policy to respect the mos regionis ("regional tradition" or "law of the land") and to regard local laws as a source of legal precedent and social stability.[88][217] The compatibility of Roman and local law was thought to reflect an underlying ius gentium, the "law of nations" or international law regarded as common and customary among all human communities.[218] If the particulars of provincial law conflicted with Roman law or custom, Roman courts heard appeals, and the emperor held final authority to render a decision.[88][219][220]
 +
 
 +
In the West, law had been administered on a highly localized or tribal basis, and private property rights may have been a novelty of the Roman era, particularly among Celtic peoples. Roman law facilitated the acquisition of wealth by a pro-Roman elite who found their new privileges as citizens to be advantageous.[88] The extension of universal citizenship to all free inhabitants of the Empire in 212 required the uniform application of Roman law, replacing the local law codes that had applied to non-citizens. Diocletian's efforts to stabilize the Empire after the Crisis of the Third Century included two major compilations of law in four years, the Codex Gregorianus and the Codex Hermogenianus, to guide provincial administrators in setting consistent legal standards.[221]
 +
 
 +
The pervasive exercise of Roman law throughout Western Europe led to its enormous influence on the Western legal tradition, reflected by the continued use of Latin legal terminology in modern law.
 +
 
 +
Taxation
 +
Taxation under the Empire amounted to about 5% of the Empire's gross product.[222] The typical tax rate paid by individuals ranged from 2 to 5%.[223] The tax code was "bewildering" in its complicated system of direct and indirect taxes, some paid in cash and some in kind. Taxes might be specific to a province, or kinds of properties such as fisheries or salt evaporation ponds; they might be in effect for a limited time.[224] Tax collection was justified by the need to maintain the military,[46][225] and taxpayers sometimes got a refund if the army captured a surplus of booty.[226] In-kind taxes were accepted from less-monetized areas, particularly those who could supply grain or goods to army camps.[227]
 +
 
 +
 
 +
Personification of the River Nile and his children, from the Temple of Serapis and Isis in Rome (1st century AD)
 +
The primary source of direct tax revenue was individuals, who paid a poll tax and a tax on their land, construed as a tax on its produce or productive capacity.[223] Supplemental forms could be filed by those eligible for certain exemptions; for example, Egyptian farmers could register fields as fallow and tax-exempt depending on flood patterns of the Nile.[228] Tax obligations were determined by the census, which required each head of household to appear before the presiding official and provide a head count of his household, as well as an accounting of property he owned that was suitable for agriculture or habitation.[228]
 +
 
 +
A major source of indirect-tax revenue was the portoria, customs and tolls on imports and exports, including among provinces.[223] Special taxes were levied on the slave trade. Towards the end of his reign, Augustus instituted a 4% tax on the sale of slaves,[229] which Nero shifted from the purchaser to the dealers, who responded by raising their prices.[230] An owner who manumitted a slave paid a "freedom tax", calculated at 5% of value.[231]
 +
 
 +
An inheritance tax of 5% was assessed when Roman citizens above a certain net worth left property to anyone but members of their immediate family. Revenues from the estate tax and from a 1% sales tax on auctions went towards the veterans' pension fund (aerarium militare).[223]
 +
 
 +
Low taxes helped the Roman aristocracy increase their wealth, which equalled or exceeded the revenues of the central government. An emperor sometimes replenished his treasury by confiscating the estates of the "super-rich", but in the later period, the resistance of the wealthy to paying taxes was one of the factors contributing to the collapse of the Empire.[46]
 +
 
 +
Economy
 +
Main article: Roman economy
 +
Moses Finley was the chief proponent of the primitivist view that the Roman economy was "underdeveloped and underachieving," characterized by subsistence agriculture; urban centres that consumed more than they produced in terms of trade and industry; low-status artisans; slowly developing technology; and a "lack of economic rationality."[232] Current views are more complex. Territorial conquests permitted a large-scale reorganization of land use that resulted in agricultural surplus and specialization, particularly in north Africa.[233] Some cities were known for particular industries or commercial activities, and the scale of building in urban areas indicates a significant construction industry.[233] Papyri preserve complex accounting methods that suggest elements of economic rationalism,[234] and the Empire was highly monetized.[235] Although the means of communication and transport were limited in antiquity, transportation in the 1st and 2nd centuries expanded greatly, and trade routes connected regional economies.[236] The supply contracts for the army, which pervaded every part of the Empire, drew on local suppliers near the base (castrum), throughout the province, and across provincial borders.[237] The Empire is perhaps best thought of as a network of regional economies, based on a form of "political capitalism" in which the state monitored and regulated commerce to assure its own revenues.[238] Economic growth, though not comparable to modern economies, was greater than that of most other societies prior to industrialization.[234]
 +
 
 +
Socially, economic dynamism opened up one of the avenues of social mobility in the Roman Empire. Social advancement was thus not dependent solely on birth, patronage, good luck, or even extraordinary ability. Although aristocratic values permeated traditional elite society, a strong tendency towards plutocracy is indicated by the wealth requirements for census rank. Prestige could be obtained through investing one's wealth in ways that advertised it appropriately: grand country estates or townhouses, durable luxury items such as jewels and silverware, public entertainments, funerary monuments for family members or coworkers, and religious dedications such as altars. Guilds (collegia) and corporations (corpora) provided support for individuals to succeed through networking, sharing sound business practices, and a willingness to work.[165]
 +
 
 +
Currency and banking
 +
See also: Roman currency and Roman finance
 +
Currency denominations[citation needed]
 +
27 BC–AD 212:
 +
1 gold aureus (1/40 lb. of gold, devalued to 1/50 lb. by 212)
 +
= 25 silver denarii
 +
= 100 bronze sestertii
 +
= 400 copper asses
 +
294–312:
 +
1 gold aureus solidus (1/60 lb. of gold)
 +
= 10 silver argentei
 +
= 40 bronze folles
 +
= 1,000 debased metal denarii
 +
312 onwards:
 +
1 gold solidus (1/72 lb.)
 +
= 24 silver siliquae
 +
= 180 bronze folles
 +
The early Empire was monetized to a near-universal extent, in the sense of using money as a way to express prices and debts.[239] The sestertius (plural sestertii, English "sesterces", symbolized as HS) was the basic unit of reckoning value into the 4th century,[240] though the silver denarius, worth four sesterces, was used also for accounting beginning in the Severan dynasty.[241] The smallest coin commonly circulated was the bronze as (plural asses), one-fourth sestertius.[242] Bullion and ingots seem not to have counted as pecunia, "money," and were used only on the frontiers for transacting business or buying property. Romans in the 1st and 2nd centuries counted coins, rather than weighing them—an indication that the coin was valued on its face, not for its metal content. This tendency towards fiat money led eventually to the debasement of Roman coinage, with consequences in the later Empire.[243] The standardization of money throughout the Empire promoted trade and market integration.[239] The high amount of metal coinage in circulation increased the money supply for trading or saving.[244]
 +
 
 +
Rome had no central bank, and regulation of the banking system was minimal. Banks of classical antiquity typically kept less in reserves than the full total of customers' deposits. A typical bank had fairly limited capital, and often only one principal, though a bank might have as many as six to fifteen principals. Seneca assumes that anyone involved in commerce needs access to credit.[243]
 +
 
 +
 
 +
Solidus issued under Constantine II, and on the reverse Victoria, one of the last deities to appear on Roman coins, gradually transforming into an angel under Christian rule[245]
 +
A professional deposit banker (argentarius, coactor argentarius, or later nummularius) received and held deposits for a fixed or indefinite term, and lent money to third parties. The senatorial elite were involved heavily in private lending, both as creditors and borrowers, making loans from their personal fortunes on the basis of social connections.[243][246] The holder of a debt could use it as a means of payment by transferring it to another party, without cash changing hands. Although it has sometimes been thought that ancient Rome lacked "paper" or documentary transactions, the system of banks throughout the Empire also permitted the exchange of very large sums without the physical transfer of coins, in part because of the risks of moving large amounts of cash, particularly by sea. Only one serious credit shortage is known to have occurred in the early Empire, a credit crisis in 33 AD that put a number of senators at risk; the central government rescued the market through a loan of 100 million HS made by the emperor Tiberius to the banks (mensae).[247] Generally, available capital exceeded the amount needed by borrowers.[243] The central government itself did not borrow money, and without public debt had to fund deficits from cash reserves.[248]
 +
 
 +
Emperors of the Antonine and Severan dynasties overall debased the currency, particularly the denarius, under the pressures of meeting military payrolls.[240] Sudden inflation during the reign of Commodus damaged the credit market.[243] In the mid-200s, the supply of specie contracted sharply.[240] Conditions during the Crisis of the Third Century—such as reductions in long-distance trade, disruption of mining operations, and the physical transfer of gold coinage outside the empire by invading enemies—greatly diminished the money supply and the banking sector by the year 300.[240][243] Although Roman coinage had long been fiat money or fiduciary currency, general economic anxieties came to a head under Aurelian, and bankers lost confidence in coins legitimately issued by the central government. Despite Diocletian's introduction of the gold solidus and monetary reforms, the credit market of the Empire never recovered its former robustness.[243]
 +
 
 +
Mining and metallurgy
 +
Main article: Roman metallurgy
 +
See also: Mining in Roman Britain
 +
 
 +
Landscape resulting from the ruina montium mining technique at Las Médulas, Spain, one of the most important gold mines in the Roman Empire
 +
The main mining regions of the Empire were the Iberian Peninsula (gold, silver, copper, tin, lead); Gaul (gold, silver, iron); Britain (mainly iron, lead, tin), the Danubian provinces (gold, iron); Macedonia and Thrace (gold, silver); and Asia Minor (gold, silver, iron, tin). Intensive large-scale mining—of alluvial deposits, and by means of open-cast mining and underground mining—took place from the reign of Augustus up to the early 3rd century AD, when the instability of the Empire disrupted production. The gold mines of Dacia, for instance, were no longer available for Roman exploitation after the province was surrendered in 271. Mining seems to have resumed to some extent during the 4th century.[249]
 +
 
 +
Hydraulic mining, which Pliny referred to as ruina montium ("ruin of the mountains"), allowed base and precious metals to be extracted on a proto-industrial scale.[250] The total annual iron output is estimated at 82,500 tonnes.[251][252][253] Copper was produced at an annual rate of 15,000 t,[250][254] and lead at 80,000 t,[250][255][256] both production levels unmatched until the Industrial Revolution;[254][255][256][257] Hispania alone had a 40% share in world lead production.[255] The high lead output was a by-product of extensive silver mining which reached 200 t per annum. At its peak around the mid-2nd century AD, the Roman silver stock is estimated at 10,000 t, five to ten times larger than the combined silver mass of medieval Europe and the Caliphate around 800 AD.[256][258] As an indication of the scale of Roman metal production, lead pollution in the Greenland ice sheet quadrupled over its prehistoric levels during the Imperial era and dropped again thereafter.[259]
 +
 
 +
Transportation and communication
 +
See also: Roman roads
 +
 
 +
Gallo-Roman relief depicting a river boat transporting wine barrels, an invention of the Gauls that came into widespread use during the 2nd century; above, wine is stored in the traditional amphorae, some covered in wicker[260][261]
 +
The Roman Empire completely encircled the Mediterranean, which they called "our sea" (mare nostrum).[262] Roman sailing vessels navigated the Mediterranean as well as the major rivers of the Empire, including the Guadalquivir, Ebro, Rhône, Rhine, Tiber and Nile.[263] Transport by water was preferred where possible, and moving commodities by land was more difficult.[264] Vehicles, wheels, and ships indicate the existence of a great number of skilled woodworkers.[265]
 +
 
 +
Land transport utilized the advanced system of Roman roads, which were called "viae". These roads were primarily built for military purposes,[266] but also served commercial ends. The in-kind taxes paid by communities included the provision of personnel, animals, or vehicles for the cursus publicus, the state mail and transport service established by Augustus.[227] Relay stations were located along the roads every seven to twelve Roman miles, and tended to grow into a village or trading post.[267] A mansio (plural mansiones) was a privately run service station franchised by the imperial bureaucracy for the cursus publicus. The support staff at such a facility included muleteers, secretaries, blacksmiths, cartwrights, a veterinarian, and a few military police and couriers. The distance between mansiones was determined by how far a wagon could travel in a day.[267] Mules were the animal most often used for pulling carts, travelling about 4 mph.[268] As an example of the pace of communication, it took a messenger a minimum of nine days to travel to Rome from Mainz in the province of Germania Superior, even on a matter of urgency.[269] In addition to the mansiones, some taverns offered accommodations as well as food and drink; one recorded tab for a stay showed charges for wine, bread, mule feed, and the services of a prostitute.[270]
 +
 
 +
Trade and commodities
 +
See also: Roman commerce, Indo-Roman trade and relations, and Sino-Roman relations
 +
 
 +
A green Roman glass cup unearthed from an Eastern Han Dynasty (25–220 AD) tomb in Guangxi, southern China; the earliest Roman glassware found in China was discovered in a Western Han tomb in Guangzhou, dated to the early 1st century BC, and ostensibly came via the maritime route through the South China Sea[271]
 +
Roman provinces traded among themselves, but trade extended outside the frontiers to regions as far away as China and India.[263] The main commodity was grain.[272] Chinese trade was mostly conducted overland through middle men along the Silk Road; Indian trade, however, also occurred by sea from Egyptian ports on the Red Sea. Along these trade paths, the horse, upon which Roman expansion and commerce depended, was one of the main channels through which disease spread.[273] Also in transit for trade were olive oil, various foodstuffs, garum (fish sauce), slaves, ore and manufactured metal objects, fibres and textiles, timber, pottery, glassware, marble, papyrus, spices and materia medica, ivory, pearls, and gemstones.[274]
 +
 
 +
 
 +
The Pompeii Lakshmi, an ivory statuette from the Indian subcontinent found in the ruins of Pompeii.
 +
Though most provinces were capable of producing wine, regional varietals were desirable and wine was a central item of trade. Shortages of vin ordinaire were rare.[275][276] The major suppliers for the city of Rome were the west coast of Italy, southern Gaul, the Tarraconensis region of Hispania, and Crete. Alexandria, the second-largest city, imported wine from Laodicea in Syria and the Aegean.[277] At the retail level, taverns or speciality wine shops (vinaria) sold wine by the jug for carryout and by the drink on premises, with price ranges reflecting quality.[278]
 +
 
 +
Labour and occupations
 +
 
 +
Workers at a cloth-processing shop, in a painting from the fullonica of Veranius Hypsaeus in Pompeii
 +
 
 +
Roman hunters during the preparations, set-up of traps, and in-action hunting near Tarraco
 +
Inscriptions record 268 different occupations in the city of Rome, and 85 in Pompeii.[203] Professional associations or trade guilds (collegia) are attested for a wide range of occupations, including fishermen (piscatores), salt merchants (salinatores), olive oil dealers (olivarii), entertainers (scaenici), cattle dealers (pecuarii), goldsmiths (aurifices), teamsters (asinarii or muliones), and stonecutters (lapidarii). These are sometimes quite specialized: one collegium at Rome was strictly limited to craftsmen who worked in ivory and citrus wood.[165]
 +
 
 +
Work performed by slaves falls into five general categories: domestic, with epitaphs recording at least 55 different household jobs; imperial or public service; urban crafts and services; agriculture; and mining. Convicts provided much of the labour in the mines or quarries, where conditions were notoriously brutal.[279] In practice, there was little division of labour between slave and free,[88] and most workers were illiterate and without special skills.[280] The greatest number of common labourers were employed in agriculture: in the Italian system of industrial farming (latifundia), these may have been mostly slaves, but throughout the Empire, slave farm labour was probably less important than other forms of dependent labour by people who were technically not enslaved.[88]
 +
 
 +
Textile and clothing production was a major source of employment. Both textiles and finished garments were traded among the peoples of the Empire, whose products were often named for them or a particular town, rather like a fashion "label".[281] Better ready-to-wear was exported by businessmen (negotiatores or mercatores) who were often well-to-do residents of the production centres.[282] Finished garments might be retailed by their sales agents, who travelled to potential customers, or by vestiarii, clothing dealers who were mostly freedmen; or they might be peddled by itinerant merchants.[282] In Egypt, textile producers could run prosperous small businesses employing apprentices, free workers earning wages, and slaves.[283] The fullers (fullones) and dye workers (coloratores) had their own guilds.[284] Centonarii were guild workers who specialized in textile production and the recycling of old clothes into pieced goods.[n 13]
 +
 
 +
GDP and income distribution
 +
Further information: Roman economy § Gross domestic product
 +
Economic historians vary in their calculations of the gross domestic product of the Roman economy during the Principate.[285] In the sample years of 14, 100, and 150 AD, estimates of per capita GDP range from 166 to 380 HS. The GDP per capita of Italy is estimated as 40[286] to 66%[287] higher than in the rest of the Empire, due to tax transfers from the provinces and the concentration of elite income in the heartland. In regard to Italy, "There can be little doubt that the lower classes of Pomepii, Herculaneum and other provincial towns of the Roman Empire enjoyed a high standard of living not equaled again in Western Europe until the 19th century after Christ, "Stephen L. Dyson, Community and Society in Roman Italy, 1992, p. 177, ISBN 0-8018-4175-5 quoting J.E. Packer, "Middle and Lower Class Housing in Pompeii and Herculaneum: A Preliminary Survey," In Neue Forschung in Pompeji, pp. 133–42.
 +
 
 +
In the Scheidel–Friesen economic model, the total annual income generated by the Empire is placed at nearly 20 billion HS, with about 5% extracted by central and local government. Households in the top 1.5% of income distribution captured about 20% of income. Another 20% went to about 10% of the population who can be characterized as a non-elite middle. The remaining "vast majority" produced more than half of the total income, but lived near subsistence.[288] The elite were 1.2-1.7% and the middling " who enjoyed modest, comfortable levels of existence but not extreme wealth amounted to 6-12%" ..."while the vast majority lived around subsistence," Kyle Harper, Slavery in the Late Roman World, 275-425, 2011, pp. 55–56 quoting Scheidel and Friesen, ISBN 978-0-521-19861-5.
 +
 
 +
Architecture and engineering
 +
Main articles: Ancient Roman architecture, Roman engineering, and Roman technology
 +
 
 +
Amphitheatres of the Roman Empire
 +
 
 +
Construction on the Flavian Amphitheatre, more commonly known as the Colosseum, began during the reign of Vespasian
 +
The chief Roman contributions to architecture were the arch, vault and the dome. Even after more than 2,000 years some Roman structures still stand, due in part to sophisticated methods of making cements and concrete.[289][290] Roman roads are considered the most advanced roads built until the early 19th century. The system of roadways facilitated military policing, communications, and trade. The roads were resistant to floods and other environmental hazards. Even after the collapse of the central government, some roads remained usable for more than a thousand years.
 +
 
 +
Roman bridges were among the first large and lasting bridges, built from stone with the arch as the basic structure. Most utilized concrete as well. The largest Roman bridge was Trajan's bridge over the lower Danube, constructed by Apollodorus of Damascus, which remained for over a millennium the longest bridge to have been built both in terms of overall span and length.[291][292][293]
 +
 
 +
The Romans built many dams and reservoirs for water collection, such as the Subiaco Dams, two of which fed the Anio Novus, one of the largest aqueducts of Rome.[294][295][296] They built 72 dams just on the Iberian peninsula, and many more are known across the Empire, some still in use. Several earthen dams are known from Roman Britain, including a well-preserved example from Longovicium (Lanchester).
 +
 
 +
 
 +
The Pont du Gard aqueduct, which crosses the Gardon River in southern France, is on UNESCO's list of World Heritage Sites
 +
The Romans constructed numerous aqueducts. A surviving treatise by Frontinus, who served as curator aquarum (water commissioner) under Nerva, reflects the administrative importance placed on ensuring the water supply. Masonry channels carried water from distant springs and reservoirs along a precise gradient, using gravity alone. After the water passed through the aqueduct, it was collected in tanks and fed through pipes to public fountains, baths, toilets, or industrial sites.[297] The main aqueducts in the city of Rome were the Aqua Claudia and the Aqua Marcia.[298] The complex system built to supply Constantinople had its most distant supply drawn from over 120 km away along a sinuous route of more than 336 km.[299] Roman aqueducts were built to remarkably fine tolerance, and to a technological standard that was not to be equalled until modern times.[300] The Romans also made use of aqueducts in their extensive mining operations across the empire, at sites such as Las Medulas and Dolaucothi in South Wales.[301]
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 +
Insulated glazing (or "double glazing") was used in the construction of public baths. Elite housing in cooler climates might have hypocausts, a form of central heating. The Romans were the first culture to assemble all essential components of the much later steam engine, when Hero built the aeolipile. With the crank and connecting rod system, all elements for constructing a steam engine (invented in 1712)—Hero's aeolipile (generating steam power), the cylinder and piston (in metal force pumps), non-return valves (in water pumps), gearing (in water mills and clocks)—were known in Roman times.[302]
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 +
Daily life
 +
Main article: Culture of ancient Rome
 +
 
 +
Cityscape from the Villa Boscoreale (60s AD)
 +
City and country
 +
In the ancient world, a city was viewed as a place that fostered civilization by being "properly designed, ordered, and adorned."[303] Augustus undertook a vast building programme in Rome, supported public displays of art that expressed the new imperial ideology, and reorganized the city into neighbourhoods (vici) administered at the local level with police and firefighting services.[304] A focus of Augustan monumental architecture was the Campus Martius, an open area outside the city centre that in early times had been devoted to equestrian sports and physical training for youth. The Altar of Augustan Peace (Ara Pacis Augustae) was located there, as was an obelisk imported from Egypt that formed the pointer (gnomon) of a horologium. With its public gardens, the Campus became one of the most attractive places in the city to visit.[304]
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 +
City planning and urban lifestyles had been influenced by the Greeks from an early period,[305] and in the eastern Empire, Roman rule accelerated and shaped the local development of cities that already had a strong Hellenistic character. Cities such as Athens, Aphrodisias, Ephesus and Gerasa altered some aspects of city planning and architecture to conform to imperial ideals, while also expressing their individual identity and regional preeminence.[306][307] In the areas of the western Empire inhabited by Celtic-speaking peoples, Rome encouraged the development of urban centres with stone temples, forums, monumental fountains, and amphitheatres, often on or near the sites of the preexisting walled settlements known as oppida.[308][309][n 14] Urbanization in Roman Africa expanded on Greek and Punic cities along the coast.[267]
 +
 
 +
 
 +
Aquae Sulis in Bath, England: architectural features above the level of the pillar bases are a later reconstruction
 +
The network of cities throughout the Empire (coloniae, municipia, civitates or in Greek terms poleis) was a primary cohesive force during the Pax Romana.[310] Romans of the 1st and 2nd centuries AD were encouraged by imperial propaganda to "inculcate the habits of peacetime".[303][311] As the classicist Clifford Ando has noted:
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 +
Most of the cultural appurtenances popularly associated with imperial culture—public cult and its games and civic banquets, competitions for artists, speakers, and athletes, as well as the funding of the great majority of public buildings and public display of art—were financed by private individuals, whose expenditures in this regard helped to justify their economic power and legal and provincial privileges.[312]
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 +
Even the Christian polemicist Tertullian declared that the world of the late 2nd century was more orderly and well-cultivated than in earlier times: "Everywhere there are houses, everywhere people, everywhere the res publica, the commonwealth, everywhere life."[313] The decline of cities and civic life in the 4th century, when the wealthy classes were unable or disinclined to support public works, was one sign of the Empire's imminent dissolution.[314]
 +
 
 +
 
 +
Public toilets (latrinae) from Ostia Antica
 +
In the city of Rome, most people lived in multistory apartment buildings (insulae) that were often squalid firetraps. Public facilities—such as baths (thermae), toilets that were flushed with running water (latrinae), conveniently located basins or elaborate fountains (nymphea) delivering fresh water,[309] and large-scale entertainments such as chariot races and gladiator combat—were aimed primarily at the common people who lived in the insulae.[315] Similar facilities were constructed in cities throughout the Empire, and some of the best-preserved Roman structures are in Spain, southern France, and northern Africa.
 +
 
 +
The public baths served hygienic, social and cultural functions.[316] Bathing was the focus of daily socializing in the late afternoon before dinner.[317] Roman baths were distinguished by a series of rooms that offered communal bathing in three temperatures, with varying amenities that might include an exercise and weight-training room, sauna, exfoliation spa (where oils were massaged into the skin and scraped from the body with a strigil), ball court, or outdoor swimming pool. Baths had hypocaust heating: the floors were suspended over hot-air channels that circulated warmth.[318] Mixed nude bathing was not unusual in the early Empire, though some baths may have offered separate facilities or hours for men and women. Public baths were a part of urban culture throughout the provinces, but in the late 4th century, individual tubs began to replace communal bathing. Christians were advised to go to the baths for health and cleanliness, not pleasure, but to avoid the games (ludi), which were part of religious festivals they considered "pagan". Tertullian says that otherwise Christians not only availed themselves of the baths, but participated fully in commerce and society.[319]
 +
 
 +
 
 +
Reconstructed peristyle garden based on the House of the Vettii
 +
Rich families from Rome usually had two or more houses, a townhouse (domus, plural domūs) and at least one luxury home (villa) outside the city. The domus was a privately owned single-family house, and might be furnished with a private bath (balneum),[318] but it was not a place to retreat from public life.[320] Although some neighbourhoods of Rome show a higher concentration of well-to-do houses, the rich did not live in segregated enclaves. Their houses were meant to be visible and accessible. The atrium served as a reception hall in which the paterfamilias (head of household) met with clients every morning, from wealthy friends to poorer dependents who received charity.[304] It was also a centre of family religious rites, containing a shrine and the images of family ancestors.[321] The houses were located on busy public roads, and ground-level spaces facing the street were often rented out as shops (tabernae).[322] In addition to a kitchen garden—windowboxes might substitute in the insulae—townhouses typically enclosed a peristyle garden that brought a tract of nature, made orderly, within walls.[323][324]
 +
 
 +
 
 +
Birds and fountain within a garden setting, with oscilla (hanging masks)[325] above, in a painting from Pompeii
 +
The villa by contrast was an escape from the bustle of the city, and in literature represents a lifestyle that balances the civilized pursuit of intellectual and artistic interests (otium) with an appreciation of nature and the agricultural cycle.[326] Ideally a villa commanded a view or vista, carefully framed by the architectural design.[327] It might be located on a working estate, or in a "resort town" situated on the seacoast, such as Pompeii and Herculaneum.
 +
 
 +
The programme of urban renewal under Augustus, and the growth of Rome's population to as many as 1 million people, was accompanied by a nostalgia for rural life expressed in the arts. Poetry praised the idealized lives of farmers and shepherds. The interiors of houses were often decorated with painted gardens, fountains, landscapes, vegetative ornament,[327] and animals, especially birds and marine life, rendered accurately enough that modern scholars can sometimes identify them by species.[328] The Augustan poet Horace gently satirized the dichotomy of urban and rural values in his fable of the city mouse and the country mouse, which has often been retold as a children's story.[329][330][331]
 +
 
 +
On a more practical level, the central government took an active interest in supporting agriculture.[332] Producing food was the top priority of land use.[333] Larger farms (latifundia) achieved an economy of scale that sustained urban life and its more specialized division of labour.[332] Small farmers benefited from the development of local markets in towns and trade centres. Agricultural techniques such as crop rotation and selective breeding were disseminated throughout the Empire, and new crops were introduced from one province to another, such as peas and cabbage to Britain.[334]
 +
 
 +
Maintaining an affordable food supply to the city of Rome had become a major political issue in the late Republic, when the state began to provide a grain dole (annona) to citizens who registered for it.[332] About 200,000–250,000 adult males in Rome received the dole, amounting to about 33 kg. per month, for a per annum total of about 100,000 tons of wheat primarily from Sicily, north Africa, and Egypt.[335] The dole cost at least 15% of state revenues,[332] but improved living conditions and family life among the lower classes,[336] and subsidized the rich by allowing workers to spend more of their earnings on the wine and olive oil produced on the estates of the landowning class.[332]
 +
 
 +
 
 +
Bread stall, from a Pompeiian wall painting
 +
The grain dole also had symbolic value: it affirmed both the emperor's position as universal benefactor, and the right of all citizens to share in "the fruits of conquest".[332] The annona, public facilities, and spectacular entertainments mitigated the otherwise dreary living conditions of lower-class Romans, and kept social unrest in check. The satirist Juvenal, however, saw "bread and circuses" (panem et circenses) as emblematic of the loss of republican political liberty:[337][338]
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 +
The public has long since cast off its cares: the people that once bestowed commands, consulships, legions and all else, now meddles no more and longs eagerly for just two things: bread and circuses.[339]
 +
 
 +
Food and dining
 +
Main article: Food and dining in the Roman Empire
 +
See also: Grain supply to the city of Rome and Ancient Rome and wine
 +
Most apartments in Rome lacked kitchens, though a charcoal brazier could be used for rudimentary cookery.[340][341] Prepared food was sold at pubs and bars, inns, and food stalls (tabernae, cauponae, popinae, thermopolia).[342] Carryout and restaurant dining were for the lower classes; fine dining could be sought only at private dinner parties in well-to-do houses with a chef (archimagirus) and trained kitchen staff,[343] or at banquets hosted by social clubs (collegia).[344]
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Most people would have consumed at least 70% of their daily calories in the form of cereals and legumes.[345] Puls (pottage) was considered the aboriginal food of the Romans.[346][347] The basic grain pottage could be elaborated with chopped vegetables, bits of meat, cheese, or herbs to produce dishes similar to polenta or risotto.[348]
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 +
An Ostian taberna for eating and drinking; the faded painting over the counter pictured eggs, olives, fruit and radishes[349]
 +
Urban populations and the military preferred to consume their grain in the form of bread.[345] Mills and commercial ovens were usually combined in a bakery complex.[350] By the reign of Aurelian, the state had begun to distribute the annona as a daily ration of bread baked in state factories, and added olive oil, wine, and pork to the dole.[332][351][352]
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 +
The importance of a good diet to health was recognized by medical writers such as Galen (2nd century AD), whose treatises included one On Barley Soup. Views on nutrition were influenced by schools of thought such as humoral theory.[353]
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Roman literature focuses on the dining habits of the upper classes,[354] for whom the evening meal (cena) had important social functions.[355] Guests were entertained in a finely decorated dining room (triclinium), often with a view of the peristyle garden. Diners lounged on couches, leaning on the left elbow. By the late Republic, if not earlier, women dined, reclined, and drank wine along with men.[356]
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The most famous description of a Roman meal is probably Trimalchio's dinner party in the Satyricon, a fictional extravaganza that bears little resemblance to reality even among the most wealthy.[357] The poet Martial describes serving a more plausible dinner, beginning with the gustatio ("tasting" or "appetizer"), which was a composed salad of mallow leaves, lettuce, chopped leeks, mint, arugula, mackerel garnished with rue, sliced eggs, and marinated sow udder. The main course was succulent cuts of kid, beans, greens, a chicken, and leftover ham, followed by a dessert of fresh fruit and vintage wine.[358] The Latin expression for a full-course dinner was ab ovo usque mala, "from the egg to the apples," equivalent to the English "from soup to nuts."[359]
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 +
Still life on a 2nd-century Roman mosaic
 +
A book-length collection of Roman recipes is attributed to Apicius, a name for several figures in antiquity that became synonymous with "gourmet."[360] Roman "foodies" indulged in wild game, fowl such as peacock and flamingo, large fish (mullet was especially prized), and shellfish. Luxury ingredients were brought by the fleet from the far reaches of empire, from the Parthian frontier to the Straits of Gibraltar.[361]
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Refined cuisine could be moralized as a sign of either civilized progress or decadent decline.[362] The early Imperial historian Tacitus contrasted the indulgent luxuries of the Roman table in his day with the simplicity of the Germanic diet of fresh wild meat, foraged fruit, and cheese, unadulterated by imported seasonings and elaborate sauces.[363] Most often, because of the importance of landowning in Roman culture, produce—cereals, legumes, vegetables, and fruit—was considered a more civilized form of food than meat. The Mediterranean staples of bread, wine, and oil were sacralized by Roman Christianity, while Germanic meat consumption became a mark of paganism,[364] as it might be the product of animal sacrifice.
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Some philosophers and Christians resisted the demands of the body and the pleasures of food, and adopted fasting as an ideal.[365] Food became simpler in general as urban life in the West diminished, trade routes were disrupted,[364] and the rich retreated to the more limited self-sufficiency of their country estates. As an urban lifestyle came to be associated with decadence, the Church formally discouraged gluttony,[366] and hunting and pastoralism were seen as simple, virtuous ways of life.[364]
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 +
 
 +
Recreation and spectacles
 +
See also: Ludi, Chariot racing, and Gladiator
 +
 
 +
Wall painting depicting a sports riot at the amphitheatre of Pompeii, which led to the banning of gladiator combat in the town[367][368]
 +
When Juvenal complained that the Roman people had exchanged their political liberty for "bread and circuses", he was referring to the state-provided grain dole and the circenses, events held in the entertainment venue called a circus in Latin. The largest such venue in Rome was the Circus Maximus, the setting of horse races, chariot races, the equestrian Troy Game, staged beast hunts (venationes), athletic contests, gladiator combat, and historical re-enactments. From earliest times, several religious festivals had featured games (ludi), primarily horse and chariot races (ludi circenses).[369] Although their entertainment value tended to overshadow ritual significance, the races remained part of archaic religious observances that pertained to agriculture, initiation, and the cycle of birth and death.[n 15]
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Under Augustus, public entertainments were presented on 77 days of the year; by the reign of Marcus Aurelius, the number of days had expanded to 135.[370] Circus games were preceded by an elaborate parade (pompa circensis) that ended at the venue.[371] Competitive events were held also in smaller venues such as the amphitheatre, which became the characteristic Roman spectacle venue, and stadium. Greek-style athletics included footraces, boxing, wrestling, and the pancratium.[372] Aquatic displays, such as the mock sea battle (naumachia) and a form of "water ballet", were presented in engineered pools.[373] State-supported theatrical events (ludi scaenici) took place on temple steps or in grand stone theatres, or in the smaller enclosed theatre called an odeum.[374]
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A victor in his four-horse chariot
 +
Circuses were the largest structure regularly built in the Roman world,[375] though the Greeks had their own architectural traditions for the similarly purposed hippodrome. The Flavian Amphitheatre, better known as the Colosseum, became the regular arena for blood sports in Rome after it opened in 80 AD.[376] The circus races continued to be held more frequently.[377] The Circus Maximus could seat around 150,000 spectators, and the Colosseum about 50,000 with standing room for about 10,000 more.[378] Many Roman amphitheatres, circuses and theatres built in cities outside Italy are visible as ruins today.[376] The local ruling elite were responsible for sponsoring spectacles and arena events, which both enhanced their status and drained their resources.[171]
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The physical arrangement of the amphitheatre represented the order of Roman society: the emperor presiding in his opulent box; senators and equestrians watching from the advantageous seats reserved for them; women seated at a remove from the action; slaves given the worst places, and everybody else packed in-between.[379][380][381] The crowd could call for an outcome by booing or cheering, but the emperor had the final say. Spectacles could quickly become sites of social and political protest, and emperors sometimes had to deploy force to put down crowd unrest, most notoriously at the Nika riots in the year 532, when troops under Justinian slaughtered thousands.[382][383][384][385]
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 +
The Zliten mosaic, from a dining room in present-day Libya, depicts a series of arena scenes: from top, musicians playing a Roman tuba, a water pipe organ and two horns; six pairs of gladiators with two referees; four beast fighters; and three convicts condemned to the beasts[386]
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The chariot teams were known by the colours they wore, with the Blues and Greens the most popular. Fan loyalty was fierce and at times erupted into sports riots.[383][387][388] Racing was perilous, but charioteers were among the most celebrated and well-compensated athletes.[389] One star of the sport was Diocles, from Lusitania (present-day Portugal), who raced chariots for 24 years and had career earnings of 35 million sesterces.[390][391] Horses had their fans too, and were commemorated in art and inscriptions, sometimes by name.[392][393] The design of Roman circuses was developed to assure that no team had an unfair advantage and to minimize collisions (naufragia, "shipwrecks"),[394][395] which were nonetheless frequent and spectacularly satisfying to the crowd.[396][397] The races retained a magical aura through their early association with chthonic rituals: circus images were considered protective or lucky, curse tablets have been found buried at the site of racetracks, and charioteers were often suspected of sorcery.[391][398][399][400][401] Chariot racing continued into the Byzantine period under imperial sponsorship, but the decline of cities in the 6th and 7th centuries led to its eventual demise.[375]
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The Romans thought gladiator contests had originated with funeral games and sacrifices in which select captive warriors were forced to fight to expiate the deaths of noble Romans. Some of the earliest styles of gladiator fighting had ethnic designations such as "Thracian" or "Gallic".[402][403][404] The staged combats were considered munera, "services, offerings, benefactions", initially distinct from the festival games (ludi).[403][404]
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Throughout his 40-year reign, Augustus presented eight gladiator shows in which a total of 10,000 men fought, as well as 26 staged beast hunts that resulted in the deaths of 3,500 animals.[405][406][407] To mark the opening of the Colosseum, the emperor Titus presented 100 days of arena events, with 3,000 gladiators competing on a single day.[376][408][409] Roman fascination with gladiators is indicated by how widely they are depicted on mosaics, wall paintings, lamps, and even graffiti drawings.[410]
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Gladiators were trained combatants who might be slaves, convicts, or free volunteers.[411] Death was not a necessary or even desirable outcome in matches between these highly skilled fighters, whose training represented a costly and time-consuming investment.[409][412][413] By contrast, noxii were convicts sentenced to the arena with little or no training, often unarmed, and with no expectation of survival. Physical suffering and humiliation were considered appropriate retributive justice for the crimes they had committed.[171] These executions were sometimes staged or ritualized as re-enactments of myths, and amphitheatres were equipped with elaborate stage machinery to create special effects.[171][414][415] Tertullian considered deaths in the arena to be nothing more than a dressed-up form of human sacrifice.[416][417][418]
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Modern scholars have found the pleasure Romans took in the "theatre of life and death"[419] to be one of the more difficult aspects of their civilization to understand and explain.[420][421] The younger Pliny rationalized gladiator spectacles as good for the people, a way "to inspire them to face honourable wounds and despise death, by exhibiting love of glory and desire for victory even in the bodies of slaves and criminals".[422][423] Some Romans such as Seneca were critical of the brutal spectacles, but found virtue in the courage and dignity of the defeated fighter rather than in victory[424]—an attitude that finds its fullest expression with the Christians martyred in the arena. Even martyr literature, however, offers "detailed, indeed luxuriant, descriptions of bodily suffering",[425] and became a popular genre at times indistinguishable from fiction.[426][427][428][429][430][431]
 +
 
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Personal training and play
 +
 
 +
Boys and girls playing ball games (2nd century relief from the Louvre)
 +
In the plural, ludi almost always refers to the large-scale spectator games. The singular ludus, "play, game, sport, training," had a wide range of meanings such as "word play," "theatrical performance," "board game," "primary school," and even "gladiator training school" (as in Ludus Magnus, the largest such training camp at Rome).[432][433]
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Activities for children and young people included hoop rolling and knucklebones (astragali or "jacks"). The sarcophagi of children often show them playing games. Girls had dolls, typically 15–16 cm tall with jointed limbs, made of materials such as wood, terracotta, and especially bone and ivory.[434] Ball games include trigon, which required dexterity, and harpastum, a rougher sport.[435] Pets appear often on children's memorials and in literature, including birds, dogs, cats, goats, sheep, rabbits and geese.[436]
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So-called "bikini girls" mosaic from the Villa del Casale, Roman Sicily, 4th century
 +
After adolescence, most physical training for males was of a military nature. The Campus Martius originally was an exercise field where young men developed the skills of horsemanship and warfare. Hunting was also considered an appropriate pastime. According to Plutarch, conservative Romans disapproved of Greek-style athletics that promoted a fine body for its own sake, and condemned Nero's efforts to encourage gymnastic games in the Greek manner.[437]
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Some women trained as gymnasts and dancers, and a rare few as female gladiators. The famous "bikini girls" mosaic shows young women engaging in apparatus routines that might be compared to rhythmic gymnastics.[n 16][438] Women in general were encouraged to maintain their health through activities such as playing ball, swimming, walking, reading aloud (as a breathing exercise), riding in vehicles, and travel.[439]
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Stone game board from Aphrodisias: boards could also be made of wood, with deluxe versions in costly materials such as ivory; game pieces or counters were bone, glass, or polished stone, and might be coloured or have markings or images[440]
 +
People of all ages played board games pitting two players against each other, including latrunculi ("Raiders"), a game of strategy in which opponents coordinated the movements and capture of multiple game pieces, and XII scripta ("Twelve Marks"), involving dice and arranging pieces on a grid of letters or words.[441] A game referred to as alea (dice) or tabula (the board), to which the emperor Claudius was notoriously addicted, may have been similar to backgammon, using a dice-cup (pyrgus).[440] Playing with dice as a form of gambling was disapproved of, but was a popular pastime during the December festival of the Saturnalia with its carnival, norms-overturned atmosphere.
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Clothing
 +
Main article: Clothing in ancient Rome
 +
In a status-conscious society like that of the Romans, clothing and personal adornment gave immediate visual clues about the etiquette of interacting with the wearer.[442] Wearing the correct clothing was supposed to reflect a society in good order.[443] The toga was the distinctive national garment of the Roman male citizen, but it was heavy and impractical, worn mainly for conducting political business and religious rites, and for going to court.[444][445] The clothing Romans wore ordinarily was dark or colourful, and the most common male attire seen daily throughout the provinces would have been tunics, cloaks, and in some regions trousers.[446] The study of how Romans dressed in daily life is complicated by a lack of direct evidence, since portraiture may show the subject in clothing with symbolic value, and surviving textiles from the period are rare.[445][447][448]
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Women from the wall painting at the Villa of the Mysteries, Pompeii
 +
The basic garment for all Romans, regardless of gender or wealth, was the simple sleeved tunic. The length differed by wearer: a man's reached mid-calf, but a soldier's was somewhat shorter; a woman's fell to her feet, and a child's to its knees.[449] The tunics of poor people and labouring slaves were made from coarse wool in natural, dull shades, with the length determined by the type of work they did. Finer tunics were made of lightweight wool or linen. A man who belonged to the senatorial or equestrian order wore a tunic with two purple stripes (clavi) woven vertically into the fabric: the wider the stripe, the higher the wearer's status.[449] Other garments could be layered over the tunic.
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The Imperial toga was a "vast expanse" of semi-circular white wool that could not be put on and draped correctly without assistance.[444] In his work on oratory, Quintilian describes in detail how the public speaker ought to orchestrate his gestures in relation to his toga.[443][445][450] In art, the toga is shown with the long end dipping between the feet, a deep curved fold in front, and a bulbous flap at the midsection.[445] The drapery became more intricate and structured over time, with the cloth forming a tight roll across the chest in later periods.[451] The toga praetexta, with a purple or purplish-red stripe representing inviolability, was worn by children who had not come of age, curule magistrates, and state priests. Only the emperor could wear an all-purple toga (toga picta).[452]
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Claudius wearing an early Imperial toga (see a later, more structured toga above), and the pallium as worn by a priest of Serapis,[453] sometimes identified as the emperor Julian
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In the 2nd century, emperors and men of status are often portrayed wearing the pallium, an originally Greek mantle (himation) folded tightly around the body. Women are also portrayed in the pallium. Tertullian considered the pallium an appropriate garment both for Christians, in contrast to the toga, and for educated people, since it was associated with philosophers.[443][445][454] By the 4th century, the toga had been more or less replaced by the pallium as a garment that embodied social unity.[455]
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Roman clothing styles changed over time, though not as rapidly as fashions today.[456] In the Dominate, clothing worn by both soldiers and government bureaucrats became highly decorated, with woven or embroidered stripes (clavi) and circular roundels (orbiculi) applied to tunics and cloaks. These decorative elements consisted of geometrical patterns, stylized plant motifs, and in more elaborate examples, human or animal figures.[457] The use of silk increased, and courtiers of the later Empire wore elaborate silk robes. The militarization of Roman society, and the waning of cultural life based on urban ideals, affected habits of dress: heavy military-style belts were worn by bureaucrats as well as soldiers, and the toga was abandoned.[458]
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The arts
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Main article: Roman art
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The Wedding of Zephyrus and Chloris (54–68 AD, Pompeian Fourth Style) within painted architectural panels from the Casa del Naviglio
 +
People visiting or living in Rome or the cities throughout the Empire would have seen art in a range of styles and media on a daily basis. Public or official art—including sculpture, monuments such as victory columns or triumphal arches, and the iconography on coins—is often analysed for its historical significance or as an expression of imperial ideology.[459][460] At Imperial public baths, a person of humble means could view wall paintings, mosaics, statues, and interior decoration often of high quality.[461] In the private sphere, objects made for religious dedications, funerary commemoration, domestic use, and commerce can show varying degrees of aesthetic quality and artistic skill.[462] A wealthy person might advertise his appreciation of culture through painting, sculpture, and decorative arts at his home—though some efforts strike modern viewers and some ancient connoisseurs as strenuous rather than tasteful.[463] Greek art had a profound influence on the Roman tradition, and some of the most famous examples of Greek statues are known only from Roman Imperial versions and the occasional description in a Greek or Latin literary source.[464]
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Despite the high value placed on works of art, even famous artists were of low social status among the Greeks and Romans, who regarded artists, artisans, and craftsmen alike as manual labourers. At the same time, the level of skill required to produce quality work was recognized, and even considered a divine gift.[465]
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Portraiture
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Main article: Roman portraiture
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Two portraits circa 130 AD: the empress Vibia Sabina (left); and the Antinous Mondragone, one of the abundant likenesses of Hadrian's famously beautiful male companion Antinous
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Portraiture, which survives mainly in the medium of sculpture, was the most copious form of imperial art. Portraits during the Augustan period utilize youthful and classical proportions, evolving later into a mixture of realism and idealism.[466] Republican portraits had been characterized by a "warts and all" verism, but as early as the 2nd century BC, the Greek convention of heroic nudity was adopted sometimes for portraying conquering generals.[467] Imperial portrait sculptures may model the head as mature, even craggy, atop a nude or seminude body that is smooth and youthful with perfect musculature; a portrait head might even be added to a body created for another purpose.[468] Clothed in the toga or military regalia, the body communicates rank or sphere of activity, not the characteristics of the individual.[469]
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Women of the emperor's family were often depicted dressed as goddesses or divine personifications such as Pax ("Peace"). Portraiture in painting is represented primarily by the Fayum mummy portraits, which evoke Egyptian and Roman traditions of commemorating the dead with the realistic painting techniques of the Empire. Marble portrait sculpture would have been painted, and while traces of paint have only rarely survived the centuries, the Fayum portraits indicate why ancient literary sources marvelled at how lifelike artistic representations could be.[470]
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The bronze Drunken Satyr, excavated at Herculaneum and exhibited in the 18th century, inspired an interest among later sculptors in similar "carefree" subjects[471]
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Sculpture
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Main article: Roman sculpture
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Examples of Roman sculpture survive abundantly, though often in damaged or fragmentary condition, including freestanding statues and statuettes in marble, bronze and terracotta, and reliefs from public buildings, temples, and monuments such as the Ara Pacis, Trajan's Column, and the Arch of Titus. Niches in amphitheatres such as the Colosseum were originally filled with statues,[472][473] and no formal garden was complete without statuary.[474]
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Temples housed the cult images of deities, often by famed sculptors.[475] The religiosity of the Romans encouraged the production of decorated altars, small representations of deities for the household shrine or votive offerings, and other pieces for dedicating at temples. Divine and mythological figures were also given secular, humorous, and even obscene depictions.[citation needed]
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On the Ludovisi sarcophagus, an example of the battle scenes favoured during the Crisis of the Third Century, the "writhing and highly emotive" Romans and Goths fill the surface in a packed, anti-classical composition[476]
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Sarcophagi
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Main article: Ancient Roman sarcophagi
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Elaborately carved marble and limestone sarcophagi are characteristic of the 2nd to the 4th centuries[477] with at least 10,000 examples surviving.[478] Although mythological scenes have been most widely studied,[479] sarcophagus relief has been called the "richest single source of Roman iconography,"[480] and may also depict the deceased's occupation or life course, military scenes, and other subject matter. The same workshops produced sarcophagi with Jewish or Christian imagery.[481]
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The Primavera of Stabiae, perhaps the goddess Flora
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Painting
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Much of what is known of Roman painting is based on the interior decoration of private homes, particularly as preserved at Pompeii and Herculaneum by the eruption of Vesuvius in 79 AD. In addition to decorative borders and panels with geometric or vegetative motifs, wall painting depicts scenes from mythology and the theatre, landscapes and gardens, recreation and spectacles, work and everyday life, and frank pornography. Birds, animals, and marine life are often depicted with careful attention to realistic detail.[citation needed]
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A unique source for Jewish figurative painting under the Empire is the Dura-Europos synagogue, dubbed "the Pompeii of the Syrian Desert,"[n 17] buried and preserved in the mid-3rd century after the city was destroyed by Persians.[482][483]
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Mosaic
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Main article: Roman mosaic
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The Triumph of Neptune floor mosaic from Africa Proconsularis (present-day Tunisia), celebrating agricultural success with allegories of the Seasons, vegetation, workers and animals viewable from multiple perspectives in the room (latter 2nd century)[484]
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Mosaics are among the most enduring of Roman decorative arts, and are found on the surfaces of floors and other architectural features such as walls, vaulted ceilings, and columns. The most common form is the tessellated mosaic, formed from uniform pieces (tesserae) of materials such as stone and glass.[485] Mosaics were usually crafted on site, but sometimes assembled and shipped as ready-made panels. A mosaic workshop was led by the master artist (pictor) who worked with two grades of assistants.[486]
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Figurative mosaics share many themes with painting, and in some cases portray subject matter in almost identical compositions. Although geometric patterns and mythological scenes occur throughout the Empire, regional preferences also find expression. In North Africa, a particularly rich source of mosaics, homeowners often chose scenes of life on their estates, hunting, agriculture, and local wildlife.[484] Plentiful and major examples of Roman mosaics come also from present-day Turkey, Italy, southern France, Spain, and Portugal. More than 300 Antioch mosaics from the 3rd century are known.[citation needed]
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Opus sectile is a related technique in which flat stone, usually coloured marble, is cut precisely into shapes from which geometric or figurative patterns are formed. This more difficult technique was highly prized, and became especially popular for luxury surfaces in the 4th century, an abundant example of which is the Basilica of Junius Bassus.[487]
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Decorative arts
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See also: Ancient Roman pottery and Roman glass
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Decorative arts for luxury consumers included fine pottery, silver and bronze vessels and implements, and glassware. The manufacture of pottery in a wide range of quality was important to trade and employment, as were the glass and metalworking industries. Imports stimulated new regional centres of production. Southern Gaul became a leading producer of the finer red-gloss pottery (terra sigillata) that was a major item of trade in 1st-century Europe.[488] Glassblowing was regarded by the Romans as originating in Syria in the 1st century BC, and by the 3rd century Egypt and the Rhineland had become noted for fine glass.[489][490]
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This section contains what may be an unencyclopedic or excessive gallery of images. Galleries containing indiscriminate images of the article subject are discouraged; please help improve the section by reducing indiscriminate gallery sections or by moving relevant images beside adjacent text, in accordance with the Manual of Style on use of images. (Learn how and when to remove this template message)
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Silver cup, from the Boscoreale Treasure (early 1st century AD)
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Figural bronze oil lamps from Nova Zagora in Roman-era Bulgaria (1st–2nd century)
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Finely decorated Gallo-Roman terra sigillata bowl
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Gold earrings with gemstones, 3rd century
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Glass cage cup from the Rhineland, latter 4th century
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Seuso plate (detail)
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Performing arts
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Main articles: Theatre of ancient Rome and Music of ancient Rome
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In Roman tradition, borrowed from the Greeks, literary theatre was performed by all-male troupes that used face masks with exaggerated facial expressions that allowed audiences to "see" how a character was feeling. Such masks were occasionally also specific to a particular role, and an actor could then play multiple roles merely by switching masks. Female roles were played by men in drag (travesti). Roman literary theatre tradition is particularly well represented in Latin literature by the tragedies of Seneca. The circumstances under which Seneca's tragedies were performed are however unclear; scholarly conjectures range from minimally staged readings to full production pageants. More popular than literary theatre was the genre-defying mimus theatre, which featured scripted scenarios with free improvisation, risqué language and jokes, sex scenes, action sequences, and political satire, along with dance numbers, juggling, acrobatics, tightrope walking, striptease, and dancing bears.[491][492][493] Unlike literary theatre, mimus was played without masks, and encouraged stylistic realism in acting. Female roles were performed by women, not by men.[494] Mimus was related to the genre called pantomimus, an early form of story ballet that contained no spoken dialogue. Pantomimus combined expressive dancing, instrumental music and a sung libretto, often mythological, that could be either tragic or comic.[495][496]
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All-male theatrical troupe preparing for a masked performance, on a mosaic from the House of the Tragic Poet
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Although sometimes regarded as foreign elements in Roman culture, music and dance had existed in Rome from earliest times.[497] Music was customary at funerals, and the tibia (Greek aulos), a woodwind instrument, was played at sacrifices to ward off ill influences.[498] Song (carmen) was an integral part of almost every social occasion. The Secular Ode of Horace, commissioned by Augustus, was performed publicly in 17 BC by a mixed children's choir. Music was thought to reflect the orderliness of the cosmos, and was associated particularly with mathematics and knowledge.[499]
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Various woodwinds and "brass" instruments were played, as were stringed instruments such as the cithara, and percussion.[498] The cornu, a long tubular metal wind instrument that curved around the musician's body, was used for military signals and on parade.[498] These instruments are found in parts of the Empire where they did not originate, and indicate that music was among the aspects of Roman culture that spread throughout the provinces. Instruments are widely depicted in Roman art.[citation needed]
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The hydraulic pipe organ (hydraulis) was "one of the most significant technical and musical achievements of antiquity", and accompanied gladiator games and events in the amphitheatre, as well as stage performances. It was among the instruments that the emperor Nero played.[498]
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Although certain forms of dance were disapproved of at times as non-Roman or unmanly, dancing was embedded in religious rituals of archaic Rome, such as those of the dancing armed Salian priests and of the Arval Brothers, priesthoods which underwent a revival during the Principate.[500] Ecstatic dancing was a feature of the international mystery religions, particularly the cult of Cybele as practised by her eunuch priests the Galli[501] and of Isis. In the secular realm, dancing girls from Syria and Cadiz were extremely popular.[502]
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Like gladiators, entertainers were infames in the eyes of the law, little better than slaves even if they were technically free. "Stars", however, could enjoy considerable wealth and celebrity, and mingled socially and often sexually with the upper classes, including emperors.[503] Performers supported each other by forming guilds, and several memorials for members of the theatre community survive.[504] Theatre and dance were often condemned by Christian polemicists in the later Empire,[497] and Christians who integrated dance traditions and music into their worship practices were regarded by the Church Fathers as shockingly "pagan."[505] St. Augustine is supposed to have said that bringing clowns, actors, and dancers into a house was like inviting in a gang of unclean spirits.[506][507]
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Literacy, books, and education
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Wiki letter w.svg
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This article is missing information about the use of papyrus or parchment scrolls, which were very common before the invention of the codex. Please expand the article to include this information. Further details may exist on the talk page. (April 2017)
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Main article: Education in ancient Rome
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Pride in literacy was displayed in portraiture through emblems of reading and writing, as in this example of a couple from Pompeii (Portrait of Paquius Proculo)
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Estimates of the average literacy rate in the Empire range from 5 to 30% or higher, depending in part on the definition of "literacy".[508][509][510][511] The Roman obsession with documents and public inscriptions indicates the high value placed on the written word.[512][513][514][515][516] The Imperial bureaucracy was so dependent on writing that the Babylonian Talmud declared "if all seas were ink, all reeds were pen, all skies parchment, and all men scribes, they would be unable to set down the full scope of the Roman government's concerns."[517] Laws and edicts were posted in writing as well as read out. Illiterate Roman subjects would have someone such as a government scribe (scriba) read or write their official documents for them.[510][518] Public art and religious ceremonies were ways to communicate imperial ideology regardless of ability to read.[519] Although the Romans were not a "People of the Book", they had an extensive priestly archive, and inscriptions appear throughout the Empire in connection with statues and small votives dedicated by ordinary people to divinities, as well as on binding tablets and other "magic spells", with hundreds of examples collected in the Greek Magical Papyri.[520][521][522][523] The military produced a vast amount of written reports and service records,[524] and literacy in the army was "strikingly high".[525] Urban graffiti, which include literary quotations, and low-quality inscriptions with misspellings and solecisms indicate casual literacy among non-elites.[526][527][n 18][81] In addition, numeracy was necessary for any form of commerce.[513][528] Slaves were numerate and literate in significant numbers, and some were highly educated.[529]
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Books were expensive, since each copy had to be written out individually on a roll of papyrus (volumen) by scribes who had apprenticed to the trade.[530] The codex—a book with pages bound to a spine—was still a novelty in the time of the poet Martial (1st century AD),[531][532] but by the end of the 3rd century was replacing the volumen[530][533] and was the regular form for books with Christian content.[534] Commercial production of books had been established by the late Republic,[535] and by the 1st century AD certain neighbourhoods of Rome were known for their bookshops (tabernae librariae), which were found also in Western provincial cities such as Lugdunum (present-day Lyon, France).[536][537] The quality of editing varied wildly, and some ancient authors complain about error-ridden copies,[535][538] as well as plagiarism or forgery, since there was no copyright law.[535] A skilled slave copyist (servus litteratus) could be valued as highly as 100,000 sesterces.[539][540]
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Reconstruction of a writing tablet: the stylus was used to inscribe letters into the wax surface for drafts, casual letterwriting, and schoolwork, while texts meant to be permanent were copied onto papyrus
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Collectors amassed personal libraries,[541] such as that of the Villa of the Papyri in Herculaneum, and a fine library was part of the cultivated leisure (otium) associated with the villa lifestyle.[542] Significant collections might attract "in-house" scholars; Lucian mocked mercenary Greek intellectuals who attached themselves to philistine Roman patrons.[543] An individual benefactor might endow a community with a library: Pliny the Younger gave the city of Comum a library valued at 1 million sesterces, along with another 100,000 to maintain it.[544][545] Imperial libraries housed in state buildings were open to users as a privilege on a limited basis, and represented a literary canon from which disreputable writers could be excluded.[546][547] Books considered subversive might be publicly burned,[548] and Domitian crucified copyists for reproducing works deemed treasonous.[549][550]
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Literary texts were often shared aloud at meals or with reading groups.[551][552] Scholars such as Pliny the Elder engaged in "multitasking" by having works read aloud to them while they dined, bathed or travelled, times during which they might also dictate drafts or notes to their secretaries.[553] The multivolume Attic Nights of Aulus Gellius is an extended exploration of how Romans constructed their literary culture.[554] The reading public expanded from the 1st through the 3rd century, and while those who read for pleasure remained a minority, they were no longer confined to a sophisticated ruling elite, reflecting the social fluidity of the Empire as a whole and giving rise to "consumer literature" meant for entertainment.[555] Illustrated books, including erotica, were popular, but are poorly represented by extant fragments.[556]
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Primary education
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A teacher with two students, as a third arrives with his loculus, a writing case that would contain pens, ink pot, and a sponge to correct errors[557]
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Traditional Roman education was moral and practical. Stories about great men and women, or cautionary tales about individual failures, were meant to instil Roman values (mores maiorum). Parents and family members were expected to act as role models, and parents who worked for a living passed their skills on to their children, who might also enter apprenticeships for more advanced training in crafts or trades.[558] Formal education was available only to children from families who could pay for it, and the lack of state intervention in access to education contributed to the low rate of literacy.[559][560]
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Young children were attended by a pedagogus, or less frequently a female pedagoga, usually a Greek slave or former slave.[561] The pedagogue kept the child safe, taught self-discipline and public behaviour, attended class and helped with tutoring.[562] The emperor Julian recalled his pedagogue Mardonius, a Gothic eunuch slave who reared him from the age of 7 to 15, with affection and gratitude. Usually, however, pedagogues received little respect.[563]
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Primary education in reading, writing, and arithmetic might take place at home for privileged children whose parents hired or bought a teacher.[564] Others attended a school that was "public," though not state-supported, organized by an individual schoolmaster (ludimagister) who accepted fees from multiple parents.[565] Vernae (homeborn slave children) might share in home- or public-schooling.[566] Schools became more numerous during the Empire, and increased the opportunities for children to acquire an education.[560] School could be held regularly in a rented space, or in any available public niche, even outdoors. Boys and girls received primary education generally from ages 7 to 12, but classes were not segregated by grade or age.[567] For the socially ambitious, bilingual education in Greek as well as Latin was a must.[560]
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Quintilian provides the most extensive theory of primary education in Latin literature. According to Quintilian, each child has in-born ingenium, a talent for learning or linguistic intelligence that is ready to be cultivated and sharpened, as evidenced by the young child's ability to memorize and imitate. The child incapable of learning was rare. To Quintilian, ingenium represented a potential best realized in the social setting of school, and he argued against homeschooling. He also recognized the importance of play in child development,[n 19] and disapproved of corporal punishment because it discouraged love of learning—in contrast to the practice in most Roman primary schools of routinely striking children with a cane (ferula) or birch rod for being slow or disruptive.[568]
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Secondary education
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Mosaic from Pompeii depicting the Academy of Plato
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At the age of 14, upperclass males made their rite of passage into adulthood, and began to learn leadership roles in political, religious, and military life through mentoring from a senior member of their family or a family friend.[569] Higher education was provided by grammatici or rhetores.[570] The grammaticus or "grammarian" taught mainly Greek and Latin literature, with history, geography, philosophy or mathematics treated as explications of the text.[571] With the rise of Augustus, contemporary Latin authors such as Vergil and Livy also became part of the curriculum.[572] The rhetor was a teacher of oratory or public speaking. The art of speaking (ars dicendi) was highly prized as a marker of social and intellectual superiority, and eloquentia ("speaking ability, eloquence") was considered the "glue" of a civilized society.[573] Rhetoric was not so much a body of knowledge (though it required a command of references to the literary canon[574]) as it was a mode of expression and decorum that distinguished those who held social power.[575] The ancient model of rhetorical training—"restraint, coolness under pressure, modesty, and good humour"[576]—endured into the 18th century as a Western educational ideal.[577]
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In Latin, illiteratus (Greek agrammatos) could mean both "unable to read and write" and "lacking in cultural awareness or sophistication."[578] Higher education promoted career advancement, particularly for an equestrian in Imperial service: "eloquence and learning were considered marks of a well-bred man and worthy of reward".[579] The poet Horace, for instance, was given a top-notch education by his father, a prosperous former slave.[580][581][582]
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Urban elites throughout the Empire shared a literary culture embued with Greek educational ideals (paideia).[583] Hellenistic cities sponsored schools of higher learning as an expression of cultural achievement.[584] Young men from Rome who wished to pursue the highest levels of education often went abroad to study rhetoric and philosophy, mostly to one of several Greek schools in Athens. The curriculum in the East was more likely to include music and physical training along with literacy and numeracy.[585] On the Hellenistic model, Vespasian endowed chairs of grammar, Latin and Greek rhetoric, and philosophy at Rome, and gave teachers special exemptions from taxes and legal penalties, though primary schoolmasters did not receive these benefits. Quintilian held the first chair of grammar.[586][587] In the eastern empire, Berytus (present-day Beirut) was unusual in offering a Latin education, and became famous for its school of Roman law.[588] The cultural movement known as the Second Sophistic (1st–3rd century AD) promoted the assimilation of Greek and Roman social, educational, and aesthetic values, and the Greek proclivities for which Nero had been criticized were regarded from the time of Hadrian onward as integral to Imperial culture.[589]
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Educated women
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Portrait of a literary woman from Pompeii (ca. 50 AD)
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Literate women ranged from cultured aristocrats to girls trained to be calligraphers and scribes.[590][591] The "girlfriends" addressed in Augustan love poetry, although fictional, represent an ideal that a desirable woman should be educated, well-versed in the arts, and independent to a frustrating degree.[592][593] Education seems to have been standard for daughters of the senatorial and equestrian orders during the Empire.[566] A highly educated wife was an asset for the socially ambitious household, but one that Martial regards as an unnecessary luxury.[590]
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The woman who achieved the greatest prominence in the ancient world for her learning was Hypatia of Alexandria, who educated young men in mathematics, philosophy, and astronomy, and advised the Roman prefect of Egypt on politics. Her influence put her into conflict with the bishop of Alexandria, Cyril, who may have been implicated in her violent death in 415 at the hands of a Christian mob.[594]
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The shape of literacy
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Literacy began to decline, perhaps dramatically, during the socio-political Crisis of the Third Century.[595] After the Christianization of the Roman Empire the Christians and Church Fathers adopted and used Latin and Greek pagan literature, philosophy and natural science with a vengeance to biblical interpretation.[596]
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Edward Grant writes that:
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With the total triumph of Christianity at the end of the fourth century, the Church might have reacted against Greek pagan learning in general, and Greek philosophy in particular, finding much in the latter that was unacceptable or perhaps even offensive. They might have launched a major effort to suppress pagan learning as a danger to the Church and its doctrines.
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But they did not. Why not?
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Perhaps it was in the slow dissemination of Christianity. After four centuries as members of a distinct religion, Christians had learned to live with Greek secular learning and to utilize it for their own benefit. Their education was heavily infiltrated by Latin and Greek pagan literature and philosophy… Although Christians found certain aspects of pagan culture and learning unacceptable, they did not view them as a cancer to be cut out of the Christian body.[597]
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Julian, the only emperor after the conversion of Constantine to reject Christianity, banned Christians from teaching the Classical curriculum, on the grounds that they might corrupt the minds of youth.[587]
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While the book roll had emphasized the continuity of the text, the codex format encouraged a "piecemeal" approach to reading by means of citation, fragmented interpretation, and the extraction of maxims.[598]
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In the 5th and 6th centuries, due to the gradual decline and fall of the Western Roman Empire, reading became rarer even for those within the Church hierarchy.[599] However, in the Eastern Roman Empire, also known as Byzantine Empire, reading continued throughout the Middle Ages as reading was of primary importance as an instrument of the Byzantine civilization.[600]
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Literature
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Main article: Latin literature
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See also: Roman historiography, Church Fathers, and Latin poetry
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Statue in Constanța, Romania (the ancient colony Tomis), commemorating Ovid's exile
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In the traditional literary canon, literature under Augustus, along with that of the late Republic, has been viewed as the "Golden Age" of Latin literature, embodying the classical ideals of "unity of the whole, the proportion of the parts, and the careful articulation of an apparently seamless composition."[601] The three most influential Classical Latin poets—Vergil, Horace, and Ovid—belong to this period. Vergil wrote the Aeneid, creating a national epic for Rome in the manner of the Homeric epics of Greece. Horace perfected the use of Greek lyric metres in Latin verse. Ovid's erotic poetry was enormously popular, but ran afoul of the Augustan moral programme; it was one of the ostensible causes for which the emperor exiled him to Tomis (present-day Constanța, Romania), where he remained to the end of his life. Ovid's Metamorphoses was a continuous poem of fifteen books weaving together Greco-Roman mythology from the creation of the universe to the deification of Julius Caesar. Ovid's versions of Greek myths became one of the primary sources of later classical mythology, and his work was so influential in the Middle Ages that the 12th and 13th centuries have been called the "Age of Ovid."[602]
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The principal Latin prose author of the Augustan age is the historian Livy, whose account of Rome's founding and early history became the most familiar version in modern-era literature. Vitruvius's book De Architectura, the only complete work on architecture to survive from antiquity, also belongs to this period.
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Latin writers were immersed in the Greek literary tradition, and adapted its forms and much of its content, but Romans regarded satire as a genre in which they surpassed the Greeks. Horace wrote verse satires before fashioning himself as an Augustan court poet, and the early Principate also produced the satirists Persius and Juvenal. The poetry of Juvenal offers a lively curmudgeon's perspective on urban society.
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The period from the mid-1st century through the mid-2nd century has conventionally been called the "Silver Age" of Latin literature. Under Nero, disillusioned writers reacted to Augustanism.[603] The three leading writers—Seneca the philosopher, dramatist, and tutor of Nero; Lucan, his nephew, who turned Caesar's civil war into an epic poem; and the novelist Petronius (Satyricon)—all committed suicide after incurring the emperor's displeasure. Seneca and Lucan were from Hispania, as was the later epigrammatist and keen social observer Martial, who expressed his pride in his Celtiberian heritage.[81] Martial and the epic poet Statius, whose poetry collection Silvae had a far-reaching influence on Renaissance literature,[604] wrote during the reign of Domitian.
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The so-called "Silver Age" produced several distinguished writers, including the encyclopedist Pliny the Elder; his nephew, known as Pliny the Younger; and the historian Tacitus. The Natural History of the elder Pliny, who died during disaster relief efforts in the wake of the eruption of Vesuvius, is a vast collection on flora and fauna, gems and minerals, climate, medicine, freaks of nature, works of art, and antiquarian lore. Tacitus's reputation as a literary artist matches or exceeds his value as a historian;[605] his stylistic experimentation produced "one of the most powerful of Latin prose styles."[606] The Twelve Caesars by his contemporary Suetonius is one of the primary sources for imperial biography.
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Among Imperial historians who wrote in Greek are Dionysius of Halicarnassus, the Jewish historian Josephus, and the senator Cassius Dio. Other major Greek authors of the Empire include the biographer and antiquarian Plutarch, the geographer Strabo, and the rhetorician and satirist Lucian. Popular Greek romance novels were part of the development of long-form fiction works, represented in Latin by the Satyricon of Petronius and The Golden Ass of Apuleius.
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From the 2nd to the 4th centuries, the Christian authors who would become the Latin Church Fathers were in active dialogue with the Classical tradition, within which they had been educated. Tertullian, a convert to Christianity from Roman Africa, was the contemporary of Apuleius and one of the earliest prose authors to establish a distinctly Christian voice. After the conversion of Constantine, Latin literature is dominated by the Christian perspective.[607] When the orator Symmachus argued for the preservation of Rome's religious traditions, he was effectively opposed by Ambrose, the bishop of Milan and future saint—a debate preserved by their missives.[608]
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Brescia Casket, an ivory box with Biblical imagery (late 4th century)
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In the late 4th century, Jerome produced the Latin translation of the Bible that became authoritative as the Vulgate. Augustine, another of the Church Fathers from the province of Africa, has been called "one of the most influential writers of western culture", and his Confessions is sometimes considered the first autobiography of Western literature. In The City of God against the Pagans, Augustine builds a vision of an eternal, spiritual Rome, a new imperium sine fine that will outlast the collapsing Empire.
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In contrast to the unity of Classical Latin, the literary aesthetic of late antiquity has a tessellated quality that has been compared to the mosaics characteristic of the period.[609] A continuing interest in the religious traditions of Rome prior to Christian dominion is found into the 5th century, with the Saturnalia of Macrobius and The Marriage of Philology and Mercury of Martianus Capella. Prominent Latin poets of late antiquity include Ausonius, Prudentius, Claudian, and Sidonius. Ausonius (d. ca. 394), the Bordelaise tutor of the emperor Gratian, was at least nominally a Christian, though throughout his occasionally obscene mixed-genre poems, he retains a literary interest in the Greco-Roman gods and even druidism. The imperial panegyrist Claudian (d. 404) was a vir illustris who appears never to have converted. Prudentius (d. ca. 413), born in Hispania Tarraconensis and a fervent Christian, was thoroughly versed in the poets of the Classical tradition,[610] and transforms their vision of poetry as a monument of immortality into an expression of the poet's quest for eternal life culminating in Christian salvation.[611] Sidonius (d. 486), a native of Lugdunum, was a Roman senator and bishop of Clermont who cultivated a traditional villa lifestyle as he watched the Western empire succumb to barbarian incursions. His poetry and collected letters offer a unique view of life in late Roman Gaul from the perspective of a man who "survived the end of his world".[609][612]
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Religion
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A Roman priest, his head ritually covered with a fold of his toga, extends a patera in a gesture of libation (2nd–3rd century)
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Main articles: Religion in ancient Rome and Imperial cult (ancient Rome)
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See also: History of the Jews in the Roman Empire, Early Christianity, and Religious persecution in the Roman Empire
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The Roman siege and destruction of Jerusalem, from a Western religious manuscript, c.1504
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Religion in the Roman Empire encompassed the practices and beliefs the Romans regarded as their own, as well as the many cults imported to Rome or practised by peoples throughout the provinces. The Romans thought of themselves as highly religious, and attributed their success as a world power to their collective piety (pietas) in maintaining good relations with the gods (pax deorum). The archaic religion believed to have been handed down from the earliest kings of Rome was the foundation of the mos maiorum, "the way of the ancestors" or "tradition", viewed as central to Roman identity. There was no principle analogous to "separation of church and state". The priesthoods of the state religion were filled from the same social pool of men who held public office, and in the Imperial era, the Pontifex Maximus was the emperor.
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Roman religion was practical and contractual, based on the principle of do ut des, "I give that you might give." Religion depended on knowledge and the correct practice of prayer, ritual, and sacrifice, not on faith or dogma, although Latin literature preserves learned speculation on the nature of the divine and its relation to human affairs. For ordinary Romans, religion was a part of daily life.[613] Each home had a household shrine at which prayers and libations to the family's domestic deities were offered. Neighbourhood shrines and sacred places such as springs and groves dotted the city. Apuleius (2nd century) described the everyday quality of religion in observing how people who passed a cult place might make a vow or a fruit offering, or merely sit for a while.[614][615] The Roman calendar was structured around religious observances. In the Imperial era, as many as 135 days of the year were devoted to religious festivals and games (ludi).[616] Women, slaves, and children all participated in a range of religious activities.
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In the wake of the Republic's collapse, state religion had adapted to support the new regime of the emperors. As the first Roman emperor, Augustus justified the novelty of one-man rule with a vast programme of religious revivalism and reform. Public vows formerly made for the security of the republic now were directed at the wellbeing of the emperor. So-called "emperor worship" expanded on a grand scale the traditional Roman veneration of the ancestral dead and of the Genius, the divine tutelary of every individual. Upon death, an emperor could be made a state divinity (divus) by vote of the Senate. Imperial cult, influenced by Hellenistic ruler cult, became one of the major ways Rome advertised its presence in the provinces and cultivated shared cultural identity and loyalty throughout the Empire. Cultural precedent in the Eastern provinces facilitated a rapid dissemination of Imperial cult, extending as far as the Augustan military settlement at Najran, in present-day Saudi Arabia.[617] Rejection of the state religion became tantamount to treason against the emperor. This was the context for Rome's conflict with Christianity, which Romans variously regarded as a form of atheism and novel superstitio.
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Statuettes representing Roman and Gallic deities, for personal devotion at private shrines
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The Romans are known for the great number of deities they honoured, a capacity that earned the mockery of early Christian polemicists.[n 20] As the Romans extended their dominance throughout the Mediterranean world, their policy in general was to absorb the deities and cults of other peoples rather than try to eradicate them.[n 21] One way that Rome promoted stability among diverse peoples was by supporting their religious heritage, building temples to local deities that framed their theology within the hierarchy of Roman religion. Inscriptions throughout the Empire record the side-by-side worship of local and Roman deities, including dedications made by Romans to local gods.[613][618][619][620] By the height of the Empire, numerous cults of pseudo-foreign gods (Roman reinventions of foreign gods) were cultivated at Rome and in the provinces, among them cults of Cybele, Isis, Epona, and of solar gods such as Mithras and Sol Invictus, found as far north as Roman Britain. Because Romans had never been obligated to cultivate one god or one cult only, religious tolerance was not an issue in the sense that it is for competing monotheistic systems.[621]
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Mystery religions, which offered initiates salvation in the afterlife, were a matter of personal choice for an individual, practised in addition to carrying on one's family rites and participating in public religion. The mysteries, however, involved exclusive oaths and secrecy, conditions that conservative Romans viewed with suspicion as characteristic of "magic", conspiracy (coniuratio), and subversive activity. Sporadic and sometimes brutal attempts were made to suppress religionists who seemed to threaten traditional morality and unity. In Gaul, the power of the druids was checked, first by forbidding Roman citizens to belong to the order, and then by banning druidism altogether. At the same time, however, Celtic traditions were reinterpreted (interpretatio romana) within the context of Imperial theology, and a new Gallo-Roman religion coalesced, with its capital at the Sanctuary of the Three Gauls in Lugdunum (present-day Lyon, France). The sanctuary established precedent for Western cult as a form of Roman-provincial identity.[622]
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This funerary stele from the 3rd century is among the earliest Christian inscriptions, written in both Greek and Latin: the abbreviation D.M. at the top refers to the Di Manes, the traditional Roman spirits of the dead, but accompanies Christian fish symbolism.
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Relief from the Arch of Titus in Rome depicting a menorah and other spoils from the Temple of Jerusalem carried in Roman triumph.
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The monotheistic rigour of Judaism posed difficulties for Roman policy that led at times to compromise and the granting of special exemptions. Tertullian noted that the Jewish religion, unlike that of the Christians, was considered a religio licita, "legitimate religion." Wars between the Romans and the Jews occurred when conflict, political as well as religious, became intractable. When Caligula wanted to place a golden statue of his deified self in the Temple in Jerusalem, the potential sacrilege and likely war were prevented only by his timely death.[623] The Siege of Jerusalem in 70 AD led to the sacking of the temple and the dispersal of Jewish political power (see Jewish diaspora).
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Christianity emerged in Roman Judea as a Jewish religious sect in the 1st century AD. The religion gradually spread out of Jerusalem, initially establishing major bases in first Antioch, then Alexandria, and over time throughout the Empire as well as beyond. Imperially authorized persecutions were limited and sporadic, with martyrdoms occurring most often under the authority of local officials.[624][625][626][627][628][629]
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The first persecution by an emperor occurred under Nero, and was confined to the city of Rome. Tacitus reports that after the Great Fire of Rome in AD 64, some among the population held Nero responsible and that the emperor attempted to deflect blame onto the Christians.[630] After Nero, a major persecution occurred under the emperor Domitian[631][632] and a persecution in 177 took place at Lugdunum, the Gallo-Roman religious capital. A surviving letter from Pliny the Younger, governor of Bythinia, to the emperor Trajan describes his persecution and executions of Christians.[633] The Decian persecution of 246–251 was a serious threat to the Church, but ultimately strengthened Christian defiance.[634] Diocletian undertook what was to be the most severe persecution of Christians, lasting from 303 to 311.
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In the early 4th century, Constantine I became the first emperor to convert to Christianity. During the rest of the fourth century Christianity became the dominant religion of the Empire. The emperor Julian, under the influence of his adviser Mardonius made a short-lived attempt to revive traditional and Hellenistic religion and to affirm the special status of Judaism, but in 380 (Edict of Thessalonica), under Theodosius I Christianity became the official state church of the Roman Empire, to the exclusion of all others. From the 2nd century onward, the Church Fathers had begun to condemn the diverse religions practised throughout the Empire collectively as "pagan."[635] Pleas for religious tolerance from traditionalists such as the senator Symmachus (d. 402) were rejected, and Christian monotheism became a feature of Imperial domination. Christian heretics as well as non-Christians were subject to exclusion from public life or persecution, but Rome's original religious hierarchy and many aspects of its ritual influenced Christian forms,[636][637] and many pre-Christian beliefs and practices survived in Christian festivals and local traditions.
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Political legacy
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Main article: Legacy of the Roman Empire
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Several states claimed to be the Roman Empire's successors after the fall of the Western Roman Empire. The Holy Roman Empire, an attempt to resurrect the Empire in the West, was established in 800 when Pope Leo III crowned Frankish King Charlemagne as Roman Emperor on Christmas Day, though the empire and the imperial office did not become formalized for some decades. After the fall of Constantinople, the Russian Tsardom, as inheritor of the Byzantine Empire's Orthodox Christian tradition, counted itself the Third Rome (Constantinople having been the second). These concepts are known as Translatio imperii.[638]
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When the Ottomans, who based their state on the Byzantine model, took Constantinople in 1453, Mehmed II established his capital there and claimed to sit on the throne of the Roman Empire.[639] He even went so far as to launch an invasion of Italy with the purpose of re-uniting the Empire and invited European artists to his capital, including Gentile Bellini.[640]
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In the medieval West, "Roman" came to mean the church and the Pope of Rome. The Greek form Romaioi remained attached to the Greek-speaking Christian population of the Eastern Roman Empire, and is still used by Greeks in addition to their common appellation.[641]
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The Roman Empire's territorial legacy of controlling the Italian peninsula would influence Italian nationalism and the unification of Italy (Risorgimento) in 1861.[642]
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The Virginia State Capitol (left), built in the late 1700s, was modelled after the Maison Carrée, a Gallo-Roman temple built around 16 BC under Augustus
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In the United States, the founders were educated in the classical tradition,[643] and used classical models for landmarks and buildings in Washington, D.C., to avoid the feudal and religious connotations of European architecture such as castles and cathedrals.[644][645][646][647][648][649][650] In forming their theory of the mixed constitution, the founders looked to Athenian democracy and Roman republicanism for models, but regarded the Roman emperor as a figure of tyranny.[651][652] They nonetheless adopted Roman Imperial forms such as the dome, as represented by the US Capitol and numerous state capitol buildings, to express classical ideals through architecture.[644][653] Thomas Jefferson saw the Empire as a negative political lesson, but was a chief proponent of its architectural models. Jefferson's design for the Virginia State Capitol, for instance, is modelled directly from the Maison Carrée, a Gallo-Roman temple built under Augustus.[644][645][647][654][655] The renovations of the National Mall at the beginning of the 20th century have been viewed as expressing a more overt imperialist kinship with Rome.[656][657][658]
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See also
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Ancient Rome portal
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icon Classical Civilisation portal
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Mediterranean portal
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Ancient Near East portal
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Daqin ("Great Qin"), the ancient Chinese name for the Roman Empire; see also Sino-Roman relations
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Fall of the Western Roman Empire
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Imperial Italy
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Italian Empire
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Notes
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Other ways of referring to the "Roman Empire" among the Romans and Greeks themselves included Res publica Romana or Imperium Romanorum (also in Greek: Βασιλεία τῶν Ῥωμαίων – Basileía tôn Rhōmaíōn – ["Dominion (Literally 'kingdom' but also interpreted as 'empire') of the Romans"]) and Romania. Res publica means Roman "commonwealth" and can refer to both the Republican and the Imperial eras. Imperium Romanum (or "Romanorum") refers to the territorial extent of Roman authority. Populus Romanus ("the Roman people") was/is often used to indicate the Roman state in matters involving other nations. The term Romania, initially a colloquial term for the empire's territory as well as a collective name for its inhabitants, appears in Greek and Latin sources from the 4th century onward and was eventually carried over to the Eastern Roman Empire (see R. L. Wolff, "Romania: The Latin Empire of Constantinople" in Speculum 23 (1948), pp. 1–34 and especially pp. 2–3).
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Between 1204 and 1261 there was an interregnum when the Empire was divided into the Empire of Nicaea, the Empire of Trebizond and the Despotate of Epirus, which were all contenders for rule of the Empire. The Empire of Nicaea is considered the legitimate continuation of the Roman Empire because it managed to re-take Constantinople.
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The final emperor to rule over all of the Roman Empire's territories before its conversion to a diarchy.
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Officially the final emperor of the Western empire.
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Last emperor of the Eastern (Byzantine) empire.
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Abbreviated "HS". Prices and values are usually expressed in sesterces; see #Currency and banking for currency denominations by period.
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Translated as "power without end" in Southern
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Prudentius (348–413) in particular Christianizes the theme in his poetry, as noted by Marc Mastrangelo, The Roman Self in Late Antiquity: Prudentius and the Poetics of the Soul (Johns Hopkins University Press, 2008), pp. 73, 203. St. Augustine, however, distinguished between the secular and eternal "Rome" in The City of God. See also J. Rufus Fears, "The Cult of Jupiter and Roman Imperial Ideology," Aufstieg und Niedergang der römischen Welt II.17.1 (1981), p. 136, on how Classical Roman ideology influenced Christian Imperial doctrine; Bang, Peter Fibiger (2011) "The King of Kings: Universal Hegemony, Imperial Power, and a New Comparative History of Rome," in The Roman Empire in Context: Historical and Comparative Perspectives. John Wiley & Sons; and the Greek concept of globalism (oikouménē).
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The civis ("citizen") stands in explicit contrast to a peregrina, a foreign or non-Roman woman: A.N. Sherwin-White (1979) Roman Citizenship. Oxford University Press. pp. 211 and 268; Frier, pp. 31–32, 457. In the form of legal marriage called conubium, the father's legal status determined the child's, but conubium required that both spouses be free citizens. A soldier, for instance, was banned from marrying while in service, but if he formed a long-term union with a local woman while stationed in the provinces, he could marry her legally after he was discharged, and any children they had would be considered the offspring of citizens—in effect granting the woman retroactive citizenship. The ban was in place from the time of Augustus until it was rescinded by Septimius Severus in 197 AD. See Sara Elise Phang, The Marriage of Roman Soldiers (13 B.C.–A.D. 235): Law and Family in the Imperial Army (Brill, 2001), p. 2, and Pat Southern, The Roman Army: A Social and Institutional History (Oxford University Press, 2006), p. 144.
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That is, a double standard was in place: a married woman could have sex only with her husband, but a married man did not commit adultery if he had sex with a prostitute, slave, or person of marginalized status. See McGinn, Thomas A. J. (1991). "Concubinage and the Lex Iulia on Adultery". Transactions of the American Philological Association. 121: 335–375 (342). doi:10.2307/284457. JSTOR 284457.; Martha C. Nussbaum (2002) "The Incomplete Feminism of Musonius Rufus, Platonist, Stoic, and Roman," in The Sleep of Reason: Erotic Experience and Sexual Ethics in Ancient Greece and Rome. University of Chicago Press. p. 305, noting that custom "allowed much latitude for personal negotiation and gradual social change"; Elaine Fantham, "Stuprum: Public Attitudes and Penalties for Sexual Offences in Republican Rome," in Roman Readings: Roman Response to Greek Literature from Plautus to Statius and Quintilian (Walter de Gruyter, 2011), p. 124, citing Papinian, De adulteriis I and Modestinus, Liber Regularum I. Eva Cantarella, Bisexuality in the Ancient World (Yale University Press, 1992, 2002, originally published 1988 in Italian), p. 104; Edwards, pp. 34–35.
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The relation of the equestrian order to the "public horse" and Roman cavalry parades and demonstrations (such as the Lusus Troiae) is complex, but those who participated in the latter seem, for instance, to have been the equites who were accorded the high-status (and quite limited) seating at the theatre by the Lex Roscia theatralis. Senators could not possess the "public horse." See Wiseman, pp. 78–79.
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Ancient Gades, in Roman Spain, and Patavium, in the Celtic north of Italy, were atypically wealthy cities, and having 500 equestrians in one city was unusual. Strabo 3.169, 5.213
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Vout, p. 212. The college of centonarii is an elusive topic in scholarship, since they are also widely attested as urban firefighters; see Jinyu Liu (2009) Collegia Centonariorum: The Guilds of Textile Dealers in the Roman West. Brill. Liu sees them as "primarily tradesmen and/or manufacturers engaged in the production and distribution of low- or medium-quality woolen textiles and clothing, including felt and its products."
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Julius Caesar first applied the Latin word oppidum to this type of settlement, and even called Avaricum (Bourges, France), a center of the Bituriges, an urbs, "city." Archaeology indicates that oppida were centers of religion, trade (including import/export), and industrial production, walled for the purposes of defense, but they may not have been inhabited by concentrated populations year-round: see Harding, D.W. (2007) The Archaeology of Celtic Art. Routledge. pp. 211–212. ISBN 113426464X; Collis, John (2000) "'Celtic' Oppida," in A Comparative Study of Thirty City-state Cultures. Danske Videnskabernes Selskab. pp. 229–238; Celtic Chiefdom, Celtic State: The Evolution of Complex Social Systems. Cambridge University Press, 1995, 1999, p. 61.
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Such as the Consualia and the October Horse sacrifice: Humphrey, pp. 544, 558; Auguste Bouché-Leclercq, Manuel des Institutions Romaines (Hachette, 1886), p. 549; "Purificazione," in Thesaurus Cultus et Rituum Antiquorum (LIMC, 2004), p. 83.
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Scholars are divided in their relative emphasis on the athletic and dance elements of these exercises: Lee, H. (1984). "Athletics and the Bikini Girls from Piazza Armerina". Stadion. 10: 45–75. sees them as gymnasts, while M. Torelli, "Piazza Armerina: Note di iconologia", in La Villa romana del Casale di Piazza Armerina, edited by G. Rizza (Catania, 1988), p. 152, thinks they are dancers at the games.
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By Michael Rostovtzeff, as noted by Robin M. Jensen (1999) "The Dura-Europos Synagogue, Early-Christian Art and Religious Life in Dura Europos," in Jews, Christians and Polytheists in the Ancient Synagogue: Cultural Interaction during the Greco-Roman Period. Routledge. p. 154.
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Political slogans and obscenities are widely preserved as graffiti in Pompeii: Antonio Varone, Erotica Pompeiana: Love Inscriptions on the Walls of Pompeii ("L'Erma" di Bretschneider, 2002). Soldiers sometimes inscribed sling bullets with aggressive messages: Phang, "Military Documents, Languages, and Literacy," p. 300.
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Bloomer, W. Martin (2011) The School of Rome: Latin Studies and the Origins of Liberal Education (University of California Press, 2011), pp. 93–99; Morgan, Literate Education in the Hellenistic and Roman Worlds, p. 250. Quintilian uses the metaphor acuere ingenium, "to sharpen talent," as well as agricultural metaphors.
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For an overview of the representation of Roman religion in early Christian authors, see R.P.C. Hanson, "The Christian Attitude to Pagan Religions up to the Time of Constantine the Great," and Carlos A. Contreras, "Christian Views of Paganism," in Aufstieg und Niedergang der römischen Welt II.23.1 (1980) 871–1022.
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"This mentality," notes John T. Koch, "lay at the core of the genius of cultural assimilation which made the Roman Empire possible"; entry on "Interpretatio romana," in Celtic Culture: A Historical Encyclopedia (ABC-Clio, 2006), p. 974.
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The others are ancient Athens, and in the modern era Brazil, the Caribbean, and the United States; Bradley, p. 12.
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Millar, p. 88.
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Boardman, pp. 218–219.
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His name was Tiberius Claudius Gordianus; Boardman, p. 219.
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Bennett, Julian (1997). Trajan: Optimus Princeps : a Life and Times. Routledge. p. 5. ISBN 978-0-415-16524-2.
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Morris, p. 188
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Millar, pp. 87–88.
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Millar, p. 96.
 +
Liebeschuetz, Wolfgang (2001) "The End of the Ancient City," in The City in Late Antiquity. Taylor & Francis. pp. 26–27.
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Millar, p. 90, calls them "status-appellations."
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Millar, p. 91.
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Millar, p. 90.
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Verboven, Koenraad (2007). "The Associative Order: Status and Ethos among Roman Businessmen in Late Republic and Early Empire". Athenaeum. 95: 870–72. hdl:1854/LU-395187.
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Peachin, pp. 153–154
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Peachin, p. 475.
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The imperial cult in Roman Britain-Google docs
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Bohec, p. 8.
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Bohec, pp. 14–15.
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Plutarch, Moralia Moralia 813c and 814c
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Potter (2009), pp. 181–182
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Luttwak, Edward (1976/1979) The Grand Strategy of the Roman Empire, Johns Hopkins University Press. p. 30. ISBN 0-8018-2158-4.
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Potter (2009), p. 184.
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Potter (2009), p. 181.
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Abbott, p. 354
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Abbott, p. 345
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Abbott, p. 341
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Millar, Fergus (2004) "Emperors at Work," in Rome, the Greek World, and the East: Government, Society, and Culture in the Roman Empire. University of North Carolina Press. Vol. 2. ISBN 0807855200. pp. 3–22, especially pp. 4 and 20.
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Boardman, p. 195ff.
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Boardman, pp. 205–209.
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Boardman, pp. 202–203, 205, 210.
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Boardman, p. 211.
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Boardman, p. 212.
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Millar, p. 76.
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Boardman, p. 215.
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Boardman, p. 215
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Winterling, p. 16.
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Morris, p. 188.
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Goldsworthy 2003, p. 80.
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Edmondson, pp. 111–112.
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Tignor, Robert; et al. (2011). Worlds Together, Worlds Apart: The History of the World (3 ed.). W.W. Norton & Company. p. 262.
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Bohec, p. 9.
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Bohec, pp. 10–14.
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Goldsworthy 2003, p. 183.
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Morris, p. 196.
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Rome and Her Enemies published by Osprey, 2005, part 3: Early Empire 27BC–AD235, Ch. 9: The Romans, section: Remuneration, p. 183; ISBN 978-1-84603-336-0
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Tacitus Annales IV.5
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Goldsworthy 2003, p. 51.
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Connolly, Peter (1986). "A Reconstruction of a Roman Saddle". Britannia. 17: 353. doi:10.2307/526559. JSTOR 526559.
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Connolly, Peter; Van Driel-Murray, Carol (1991). "The Roman Cavalry Saddle". Britannia. 22: 33. doi:10.2307/526629. JSTOR 526629.
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Goldsworthy 2003, p. 114.
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Potter (2009), p. 183.
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Potter (2009), pp. 177–179. Most government records that are preserved come from Roman Egypt, where the climate preserved the papyri.
 +
Potter (2009), p. 179. The exclusion of Egypt from the senatorial provinces dates to the rise of Octavian before he became Augustus: Egypt had been the stronghold of his last opposition, Mark Antony and his ally Cleopatra.
 +
Potter (2009), p. 180.
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Potter (2009), pp. 179, 187.
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Potter (2009), p. 180
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Fuhrmann, C. J. (2012) Policing the Roman Empire: Soldiers, Administration, and Public Order. Oxford University Press. pp. 197, 214, 224. ISBN 0199737843.
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Potter (2009), pp. 184–185.
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Bozeman, Adda B. (2010) Politics and Culture in International History from the Ancient Near East to the Opening of the Modern Age. Transaction Publishers. 2nd ed.. pp. 208–20
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Potter (2009), pp. 184–185
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This practice was established in the Republic; see for instance the case of Contrebian water rights heard by G. Valerius Flaccus as governor of Hispania in the 90s–80s BC.
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Digeser, Elizabeth DePalma (2000) The Making of a Christian Empire: Lactantius and Rome. Cornell University Press. p. 53.
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Morris, p. 183.
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Potter (2009), p. 187.
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Potter (2009), pp. 185–187.
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Potter (2009), p. 185
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Potter (2009), p. 185.
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Potter (2009), p. 188.
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Potter (2009), p. 186.
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Cassius Dio 55.31.4.
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Tacitus, Annales 13.31.2.
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This was the vicesima libertatis, "the twentieth for freedom"; Potter (2009), p. 187.
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Potter (2009), p. 283.
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Potter (2009), p. 285.
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Potter (2009), p. 286.
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Potter (2009), p. 292.
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Potter (2009), pp. 285–286, 296ff.
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Potter (2009), p. 296.
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Potter (2009), pp. 286, 295.
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Kessler, David and Temin, Peter (2010) "Money and Prices in the Early Roman Empire," in The Monetary Systems of the Greeks and Romans. Oxford University Press.
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Harl, Kenneth W. (19 June 1996). Coinage in the Roman Economy, 300 B.C. to A.D. 700. JHU Press. pp. 125–135. ISBN 978-0-8018-5291-6.
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Bowman, p. 333.
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Colin Wells, The Roman Empire (Harvard University Press, 1984, 1992), p. 8.
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Harris, W. V. (2010) "The Nature of Roman Money," in The Monetary Systems of the Greeks and Romans. Oxford University Press. ISBN 0199586713.
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Scheidel, Walter (2009) "The Monetary Systems of the Han and Roman Empires", in: Scheidel, Walter, ed. Rome and China. Comparative Perspectives on Ancient World Empires. Oxford University Press. ISBN 978-0-19-533690-0, pp. 137–207 (205).
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Fears, J. Rufus (1981) "The Theology of Victory at Rome: Approaches and Problem," Aufstieg und Niedergang der römischen Welt II.17.2, pp. 752 and 824, and in the same volume, "The Cult of Virtues and Roman Imperial Ideology," p. 908.
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Andreau, Jean (1999) Banking and Business in the Roman World. Cambridge University Press. p. 2.
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Tacitus, Annales 6.17.3.
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Duncan-Jones, Richard (1994) Money and Government in the Roman Empire. Cambridge University Press. pp. 3–4.
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Bowersock, p. 579.
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Wilson, Andrew (2002). "Machines, Power and the Ancient Economy". The Journal of Roman Studies. 92: 1. doi:10.2307/3184857. JSTOR 3184857.
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Craddock, Paul T. (2008): "Mining and Metallurgy", in: Oleson, John Peter (ed.): The Oxford Handbook of Engineering and Technology in the Classical World, Oxford University Press, ISBN 978-0-19-518731-1, p. 108
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Sim, David; Ridge, Isabel (2002) Iron for the Eagles. The Iron Industry of Roman Britain, Tempus, Stroud, Gloucestershire, ISBN 0-7524-1900-5. p. 23
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Healy, John F. (1978) Mining and Metallurgy in the Greek and Roman World, Thames and Hudson, London, ISBN 0-500-40035-0. p. 196. Assumes a productive capacity of c. 1.5 kg per capita.
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Hong, S.; Candelone, J.-P.; Patterson, C. C.; Boutron, C. F. (1996). "History of Ancient Copper Smelting Pollution During Roman and Medieval Times Recorded in Greenland Ice". Science. 272 (5259): 246. Bibcode:1996Sci...272..246H. doi:10.1126/science.272.5259.246.
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Hong, S; Candelone, J. P.; Patterson, C. C.; Boutron, C. F. (1994). "Greenland ice evidence of hemispheric lead pollution two millennia ago by greek and roman civilizations" (PDF). Science. 265 (5180): 1841–3. Bibcode:1994Sci...265.1841H. doi:10.1126/science.265.5180.1841. PMID 17797222.
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Settle, D. M.; Patterson, C. C. (1980). "Lead in albacore: Guide to lead pollution in Americans". Science. 207 (4436): 1167–76. Bibcode:1980Sci...207.1167S. doi:10.1126/science.6986654. PMID 6986654.
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Patterson, C. C. (1972). "Silver Stocks and Losses in Ancient and Medieval Times". The Economic History Review. 25 (2): 205–235 (tables 2, 6). doi:10.1111/j.1468-0289.1972.tb02173.x. JSTOR 2593904.
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Morris, p. 197.
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Marlière, Élise (2001). "Le tonneau en Gaule romaine" (PDF). Gallia. 58: 181–210 (184). doi:10.3406/galia.2001.3179. JSTOR 43608343.
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Bowman, p. 404.
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Greene, Kevin (1990). The Archaeology of the Roman Economy. University of California Press. p. 17. ISBN 978-0-520-07401-9.
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Boardman, p. 713.
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Boardman, p. 714.
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Ulrich, Roger Bradley (2007). Roman Woodworking. Yale University Press. pp. 1–2. ISBN 0300103417.
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Van Tilburg, Cornelis (2007). Traffic and Congestion in the Roman Empire. Routledge. p. 33.
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Stambaugh, p. 253.
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Ray Laurence, "Land Transport in Roman Italy: Costs, Practice and the Economy," in Trade, Traders and the Ancient City (Routledge, 1998), p. 129.
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Morris, p. 187.
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Holleran, p. 142.
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An, Jiayao (2002). "When Glass Was Treasured in China". In Juliano, Annette L.; Lerner, Judith A. Silk Road Studies VII: Nomads, Traders, and Holy Men Along China's Silk Road. Turnhout: Brepols Publishers. pp. 83–84. ISBN 978-2-503-52178-7.
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Boardman, p. 710.
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Swabe, Joanna (2002). Animals, Disease and Human Society: Human-animal Relations and the Rise of Veterinary Medicine. Routledge. p. 80.
 +
Boardman, pp. 717–729.
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Bowman, p. 404
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Boardman, p. 719.
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Boardman, p. 720.
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Holleran, pp. 146–147.
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Gagarin, p. 323.
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Temin, Peter (2004). "The Labor Market of the Early Roman Empire". Journal of Interdisciplinary History. 34 (4): 513. doi:10.1162/002219504773512525. JSTOR 3656762.
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Jones, pp. 184–185.
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Jones, p. 192.
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Jones, pp. 188–189.
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Jones, pp. 190–191.
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Scheidel, Walter; Morris, Ian; Saller, Richard, eds. (2007): The Cambridge Economic History of the Greco-Roman World, Cambridge University Press, ISBN 978-0-521-78053-7
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Lo Cascio, Elio; Malanima, Paolo (2009). "GDP in Pre-Modern Agrarian Economies (1–1820 AD). A Revision of the Estimates". Rivista di storia economica. 25 (3): 391–420 (391–401).
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Maddison, Angus (2007) Contours of the World Economy, 1–2030 AD. Essays in Macro-Economic History, Oxford University Press. pp. 47–51. ISBN 978-0-19-922721-1.
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Scheidel, Walter; Friesen, Steven J. (2010). "The Size of the Economy and the Distribution of Income in the Roman Empire" (PDF). Journal of Roman Studies. 99: 61. doi:10.3815/007543509789745223. JSTOR 40599740.
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MacDonald, W. L. (1982) The Architecture of the Roman Empire. Yale University Press, New Haven, fig. 131B
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Lechtman, H. N.; Hobbs, L. W. (1987). "Roman Concrete and the Roman Architectural Revolution". Ceramics and Civilization. 3: 81–128.
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Encyclopædia Britannica, Apollodorus of Damascus, "Greek engineer and architect who worked primarily for the Roman emperor Trajan."
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Sarton, George (1936). "The Unity and Diversity of the Mediterranean World". Osiris. 2: 406–463 (430). doi:10.1086/368462. JSTOR 301558.
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Calcani, Giuliana; Abdulkarim, Maamoun (2003). Apollodorus of Damascus and Trajan's Column: From Tradition to Project. L'Erma di Bretschneider. p. 11. ISBN 88-8265-233-5. ... focusing on the brilliant architect Apollodorus of Damascus. This famous Syrian personage represents ...
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Hong-Sen Yan; Marco Ceccarelli (2009). International Symposium on History of Machines and Mechanisms: Proceedings of HMM 2008. Springer. p. 86. ISBN 1-4020-9484-1. He had Syrian origins coming from Damascus
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Smith, Norman (1970). "The Roman Dams of Subiaco". Technology and Culture. 11 (1): 58–68. doi:10.2307/3102810. JSTOR 3102810.
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Smith, Norman (1971). A History of Dams. London: Peter Davies. p. 26. ISBN 0-432-15090-0.
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Schnitter, Niklaus (1978). "Römische Talsperren". Antike Welt. 8 (2): 25–32 (28).
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Chandler, Fiona (2001) The Usborne Internet Linked Encyclopedia of the Roman World. Usborne Publishing. p. 80.
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Forman, Joan (1975) The Romans, Macdonald Educational Ltd. p. 34.
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Crow, J. (2007) "Earth, walls and water in Late Antique Constantinople" in Technology in Transition AD 300–650 in ed. L.Lavan, E.Zanini & A. Sarantis Brill, Leiden
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Greene, Kevin (1990). The Archaeology of the Roman Economy. University of California Press. p. 39. ISBN 978-0-520-07401-9.
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Jones, R. F. J.; Bird, D. G. (2012). "Roman Gold-Mining in North-West Spain, II: Workings on the Rio Duerna". Journal of Roman Studies. 62: 59. doi:10.2307/298927. JSTOR 298927.
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Ritti, Tullia; Grewe, Klaus; Kessener, Paul (2007). "A Relief of a Water-powered Stone Saw Mill on a Sarcophagus at Hierapolis and its Implications". Journal of Roman Archaeology. 20: 138–163 (156, fn. 74). doi:10.1017/S1047759400005341.
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Potter (2009), p. 192.
 +
Rehak, Paul (2006) Imperium and Cosmos: Augustus and the Northern Campus Martius. University of Wisconsin Press. pp. 4–8.
 +
Stambaugh, pp. 23ff. and 244
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Raja, Rubina (2012) Urban Development and Regional Identity in the Eastern Roman Provinces 50 BC–AD 250. Museum Tusculanum Press. pp. 215–218
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Sperber, Daniel (1998) The City in Roman Palestine. Oxford University Press.
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Stambaugh, pp. 252–253
 +
Longfellow, Brenda (2011) Roman Imperialism and Civic Patronage: Form, Meaning and Ideology in Monumental Fountain Complexes. Cambridge University Press. pp. 1–2. ISBN 0521194938
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Millar, p. 79.
 +
Vergil, Aeneid 6.852
 +
Potter (2009), pp. 185–186.
 +
Tertullian, De anima 30.3 (ubique domus, ubique populus, ubique respublica, ubique uita), as cited and framed in Potter (2009), p. 185.
 +
Millar, pp. 76ff.
 +
Jones, Mark Wilson (2000) Principles of Roman Architecture. New Haven: Yale University Press.
 +
Evans, Harry B. (1994) Water Distribution in Ancient Rome, University of Michigan Press. pp. 9–10.
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Peachin, p. 366.
 +
Fagan, Garrett G. (2001). "The Genesis of the Roman Public Bath: Recent Approaches and Future Directions" (PDF). American Journal of Archaeology. 105 (3): 403. doi:10.2307/507363. JSTOR 507363.
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Ward, Roy Bowen (1992). "Women in Roman Baths". Harvard Theological Review. 85 (2): 125–147. doi:10.1017/S0017816000028820 (inactive 2018-06-28). JSTOR 1509900.
 +
Clarke, pp. 1–2.
 +
Clarke, pp. 11–12.
 +
Clarke, p. 2.
 +
Stambaugh, pp. 144, 147
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Clarke, pp. 12, 17, 22ff.
 +
Taylor, Rabun (2005). "Roman Oscilla: An Assessment". Res: Anthropology and aesthetics. 48: 83–105. doi:10.1086/RESv48n1ms20167679. JSTOR 20167679.
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Gazda, Elaine K. (1991) "Introduction", in Roman Art in the Private Sphere: Architecture and Décor of the Domus, Villa, and Insula. University of Michigan Press. p. 9. ISBN 047210196X.
 +
Clarke, p. 19.
 +
Jashemski, Wilhelmina Feemster; Meyer, Frederick G. (2002). The Natural History of Pompeii. Cambridge University Press. ISBN 978-0-521-80054-9.
 +
Horace, Satire 2.6
 +
Holzberg, Niklas (2002) The Ancient Fable: An Introduction. Indiana University Press. p. 35
 +
Bovie, Smith Palmer (2002) Introduction to Horace. Satires and Epistles. University of Chicago Press. pp. 92–93.
 +
Morris, p. 191.
 +
Boardman, p. 679.
 +
Morris, pp. 195–196.
 +
Morris, p. 191, reckoning that the surplus of wheat from the province of Egypt alone could meet and exceed the needs of the city of Rome and the provincial armies.
 +
Wiseman, T. P. (2012). "The Census in the First Century B.C". Journal of Roman Studies. 59: 59. doi:10.2307/299848. JSTOR 299848.
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Keane, Catherine (2006) Figuring Genre in Roman Satire. Oxford University Press. p. 36
 +
Köhne, Eckhart (2000) "Bread and Circuses: The Politics of Entertainment," in Gladiators and Caesars: The Power of Spectacle in Ancient Rome. University of California Press. p. 8.
 +
Juvenal, Satire 10.77–81.
 +
Stambaugh, pp. 144, 178
 +
Hinds, Kathryn (2010) Everyday Life in the Roman Empire. Marshall Cavendish. p. 90.
 +
Holleran, p. 136ff.
 +
Gagarin, p. 299.
 +
Faas, Patrick (1994, 2005) Around the Roman Table: Food and Feasting in Ancient Rome. University of Chicago Press. p. 29.
 +
Boardman, p. 681.
 +
Pliny the Elder, Natural History 19.83–84; Emily Gowers, The Loaded Table: Representation of Food in Roman Literature (Oxford University Press, 1993, 2003), p. 17
 +
Gagarin, p. 198.
 +
Stambaugh, p. 144.
 +
Holleran, pp. 136–137.
 +
Holleran, pp. 134–135.
 +
Stambaugh, p. 146
 +
Holleran, p. 134.
 +
Grant, Mark (2000) Galen on Food and Diet. Routledge. pp. 7, 11.
 +
Potter (2009), p. 354.
 +
Potter (2009), p. 356.
 +
Roller, Matthew B. (2006) Dining Posture in Ancient Rome. Princeton University Press. p. 96ff.
 +
Potter (2009), p. 359.
 +
Alcock, Joan P. (2006) Food in the Ancient World. Greenwood Press. p. 184.
 +
Donahue, John (2004) The Roman Community at Table during the Principate. University of Michigan Press. p. 9.
 +
Cathy K. Kaufman, "Remembrance of Meals Past: Cooking by Apicius' Book," in Food and the Memory: Proceedings of the Oxford Symposium on Food and Cooker p. 125ff.
 +
Suetonius, Life of Vitellius 13.2; Gowers, The Loaded Table, p. 20.
 +
Gagarin, p. 201.
 +
Tacitus, Germania 23; Gowers, The Loaded Table, p. 18.
 +
Flandrin, Jean Louis; Montanari, Massimo (1999). Food: A Culinary History from Antiquity to the Present. Columbia University Press. pp. 165–167. ISBN 978-0-231-11154-6.
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Potter (2009), pp. 365–366.
 +
Bowersock, p. 455
 +
Franklin, James L. Jr. (2001) Pompeis Difficile Est: Studies in the Political Life of Imperial Pompeii. University of Michigan Press. p. 137
 +
Laurence, Ray (2007) Roman Pompeii: Space and Society. Routledge. p. 173; recounted by Tacitus, Annals 14.17.
 +
Mary Beard, J.A. North, and S.R.F. Price, Religions of Rome: A History (Cambridge University Press, 1998), p. 66.
 +
Dyson, p. 240.
 +
Versnel, H.S. (1971) Triumphus: An Inquiry into the Origin, Development and Meaning of the Roman Triumph. Brill. pp. 96–97.
 +
Potter (1999), p. 242.
 +
Potter (1999), pp. 235–236.
 +
Potter (1999), pp. 223–224.
 +
Potter (1999), p. 303.
 +
Humphrey, pp. 1–3.
 +
Edmondson, p. 112.
 +
Dyson, pp. 237, 239.
 +
Edmondson, pp. 73–74, 106
 +
Auguet, p. 54
 +
McClelland, John (2007) Body and Mind: Sport in Europe from the Roman Empire to the Renaissance. Routledge. p. 67.
 +
Dyson, pp. 238–239
 +
Gagarin, p. 85
 +
Humphrey, p. 461
 +
McClelland, John (2007) Body and Mind: Sport in Europe from the Roman Empire to the Renaissance. Routledge. p. 61.
 +
Thomas Wiedemann, Emperors and Gladiators (Routledge, 1992, 1995), p. 15.
 +
Humphrey, pp. 459, 461, 512, 630–631
 +
Dyson, p. 237
 +
Dyson, p. 238.
 +
Potter (1999), p. 296
 +
Dyson, pp. 238–239.
 +
Humphrey, p. 238
 +
Potter (1999), p. 299.
 +
Humphrey, pp. 18–21
 +
Gagarin, p. 84.
 +
Auguet, pp. 131–132
 +
Potter (1999), p. 237.
 +
Auguet, p. 144
 +
Dickie, Matthew (2001) Magic and Magicians in the Greco-Roman World. Routledge. pp. 282–287
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Eva D'Ambra, "Racing with Death: Circus Sarcophagi and the Commemoration of Children in Roman Italy" in Constructions of Childhood in Ancient Greece and Italy (American School of Classical Studies at Athens, 2007), pp. 348–349
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Rüpke, p. 289.
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Potter (2009), p. 354
 +
Edwards, p. 59
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Potter (1999), p. 305.
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Cassio Dio 54.2.2; Res Gestae Divi Augusti 22.1, 3
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Edwards, p. 49
 +
Edmondson, p. 70.
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Cassius Dio 66.25
 +
Edwards, p. 55
 +
Edwards, p. 49.
 +
Edwards, p. 50.
 +
Potter (1999), p. 307
 +
McClelland, Body and Mind, p. 66, citing also Marcus Junkelmann.
 +
Suetonius, Nero 12.2
 +
Edmondson, p. 73.
 +
Tertullian, De spectaculis 12
 +
Edwards, pp. 59–60
 +
Potter (1999), p. 224.
 +
McDonald, Marianne and Walton, J. Michael (2007) Introduction to The Cambridge Companion to Greek and Roman Theatre. Cambridge University Press. p. 8.
 +
Kyle, Donald G. (1998) Spectacles of Death in Ancient Rome. Routledge. p. 81
 +
Edwards, p. 63.
 +
Pliny, Panegyric 33.1
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Edwards, p. 52.
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Edwards, pp. 66–67, 72.
 +
Edwards, p. 212.
 +
Bowersock, G.W. (1995) Martyrdom and Rome. Cambridge University Press. pp. 25–26
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Cavallo, p. 79
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Huber-Rebenich, Gerlinde (1999) "Hagiographic Fiction as Entertainment," in Latin Fiction: The Latin Novel in Context. Routlege. pp. 158–178
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Llewelyn, S.R. and Nobbs, A.M. (2002) "The Earliest Dated Reference to Sunday in the Papyri," in New Documents Illustrating Early Christianity. Wm. B. Eerdmans. p. 109
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Hildebrandt, Henrik (2006) "Early Christianity in Roman Pannonia—Fact or Fiction?" in Studia Patristica: Papers Presented at the Fourteenth International Conference on Patristic Studies Held in Oxford 2003. Peeters. pp. 59–64
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Ando, p. 382.
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Oxford Latin Dictionary (Oxford: Clarendon Press, 1982, 1985 reprint), pp. 1048–1049
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Habinek (2005), pp. 5, 143.
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Rawson (2003), p. 128.
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McDaniel, Walton Brooks (1906). "Some Passages concerning Ball-Games". Transactions and Proceedings of the American Philological Association. 37: 121. doi:10.2307/282704. JSTOR 282704.
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Rawson (2003), pp. 129–130.
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Eyben, Emiel (1977) Restless Youth in Ancient Rome. Routledge, pp. 79–82, 110.
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Dunbabin, Katherine M.D. (1999) Mosaics of the Greek and Roman World. Cambridge University Press. p. 133. ISBN 0521002303.
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Hanson, Ann Ellis (1991) "The Restructuring of Female Physiology at Rome," in Les écoles médicales à Rome. Université de Nantes. pp. 260, 264, particularly citing the Gynecology of Soranus.
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Austin, R. G. (2009). "Roman Board Games. II". Greece and Rome. 4 (11): 76. doi:10.1017/S0017383500003119. JSTOR 640979.
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Austin, R. G. (1934). "Roman Board Games. I". Greece and Rome. 4 (10): 24–34. doi:10.1017/s0017383500002941. JSTOR 641231.
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Gagarin, p. 230.
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Coon, Lynda L. (1997) Sacred Fictions: Holy Women and Hagiography in Late Antiquity. University of Pennsylvania Press. pp. 57–58.
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Vout, p. 216
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Bieber, Margarete (1959). "Roman Men in Greek Himation (Romani Palliati) a Contribution to the History of Copying". Proceedings of the American Philosophical Society. 103 (3): 374–417. JSTOR 985474.
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Vout, p. 218.
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Vout, pp. 204–220, especially pp. 206, 211
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Métraux, Guy P.R. (2008) "Prudery and Chic in Late Antique Clothing," in Roman Dress and the Fabrics of Roman Culture. University of Toronto Press. p. 286.
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Gagarin, p. 231.
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Quintilian, Institutio Oratoria 11.3.137–149
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Métraux, Guy P.R. (2008) "Prudery and Chic in Late Antique Clothing," in Roman Dress and the Fabrics of Roman Culture. University of Toronto Press. pp. 282–283.
 +
Cleland, Liza (2007) Greek and Roman Dress from A to Z. Routledge. p. 194.
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Modern copy of a 2nd-century original, from the Louvre.
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Tertullian, De Pallio 5.2
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Vout, p. 217.
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Gagarin, p. 232.
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D'Amato, Raffaele (2005) Roman Military Clothing (3) AD 400 to 640. Osprey. pp. 7–9. ISBN 184176843X.
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Wickham, Chris (2009) The Inheritance of Rome. Penguin Books. p. 106. ISBN 978-0-670-02098-0
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Kousser, p. 1
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Potter (2009), pp. 75–76.
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Potter (2009), pp. 82–83.
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Gazda, Elaine K. (1991) "Introduction", in Roman Art in the Private Sphere: Architecture and Décor of the Domus, Villa, and Insula. University of Michigan Press. pp. 1–3. ISBN 047210196X.
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Paul Zanker, Pompeii: Public and Private Life, translated by Deborah Lucas Schneider (Harvard University Press, 1998, originally published 1995 in German), p. 189.
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Kousser, pp. 4–5, 8.
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Gagarin, pp. 312–313.
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Toynbee, J. M. C. (December 1971). "Roman Art". The Classical Review. 21 (3): 439–442. doi:10.1017/S0009840X00221331. JSTOR 708631.
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Zanker, Paul (1988) The Power of Images in the Age of Augustus. University of Michigan Press. p. 5ff.
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Gagarin, p. 451.
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Fejfer, Jane (2008) Roman Portraits in Context. Walter de Gruyter. p. 10.
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Gagarin, p. 453.
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Kousser, p. 13
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Gagarin, pp. 274–275.
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Gagarin, p. 242.
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Kleiner, Fred S. (2007) A History of Roman Art. Wadsworth. p. 272.
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Newby, Zahra (2011) "Myth and Death: Roman Mythological Sarcophagi," in A Companion to Greek Mythology. Blackwell. p. 301.
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Elsner, p. 1.
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Elsner, p. 12.
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Elsner, p. 14.
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Elsner, pp. 1, 9.
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Hachlili, Rachel (1998) Ancient Jewish Art and Archaeology in the Diaspora. Brill. pp. 96ff.
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Schreckenberg, Heinz and Schubert, Kurt (1991) Jewish Historiography and Iconography in Early and Medieval Christianity. Fortress Press. pp. 171ff.
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Gagarin, p. 463.
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Gagarin, p. 459.
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Gagarin, pp. 459–460.
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Dunbabin, Katherine M.D. (1999) Mosaics of the Greek and Roman World. Cambridge University Press. p. 254ff. ISBN 0521002303.
 +
Gagarin, p. 202.
 +
Butcher, Kevin (2003) Roman Syria and the Near East. Getty Publications. p. 201ff. ISBN 0892367156.
 +
Bowman, p. 421.
 +
Fantham, R. Elaine (1989). "Mime: The Missing Link in Roman Literary History". The Classical World. 82 (3): 153. doi:10.2307/4350348. JSTOR 4350348.
 +
Slater, William J. (2002). "Mime Problems: Cicero Ad fam. 7.1 and Martial 9.38". Phoenix. 56 (3/4): 315. doi:10.2307/1192603. JSTOR 1192603.
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Potter (1999), p. 257.
 +
Gian Biagio Conte (1994) Latin Literature: A History. Johns Hopkins University Press. p. 128.
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Franklin, James L. (1987). "Pantomimists at Pompeii: Actius Anicetus and His Troupe". The American Journal of Philology. 108: 95. doi:10.2307/294916. JSTOR 294916.
 +
Starks, John H. Jr. (2008) "Pantomime Actresses in Latin Inscriptions," in New Directions in Ancient Pantomime. Oxford University Press. p. 95; p. 14ff.
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Naerebout, p. 146.
 +
Ginsberg‐Klar, Maria E. (2010). "The archaeology of musical instruments in Germany during the Roman period". World Archaeology. 12 (3): 313. doi:10.1080/00438243.1981.9979806. JSTOR 124243.
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Habinek (2005), p. 90ff.
 +
Naerebout, pp. 146ff.
 +
Naerebout, pp. 154, 157.
 +
Naerebout, pp. 156–157.
 +
Richlin, Amy (1993). "Not before Homosexuality: The Materiality of the cinaedus and the Roman Law against Love between Men". Journal of the History of Sexuality. 3 (4): 539–540. JSTOR 3704392.
 +
Csapo, Eric and Slater, William J. (1994) The Context of Ancient Drama. University of Michigan Press. p. 377.
 +
MacMullen, Ramsay (1984) Christianizing the Roman Empire: (A. D. 100–400). Yale University Press. pp. 74–75, 84.
 +
As quoted by Alcuin, Epistula 175 (Nescit homo, qui histriones et mimos et saltatores introduct in domum suam, quam magna eos immundorum sequitur turba spiritum)
 +
Hen, Yitzhak (1995) Culture and Religion in Merovingian Gaul, AD 481–751. Brill. p. 230.
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Harris, p. 5
 +
Johnson (2009), pp. 3–4
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Kraus, T.J. (2000). "(Il)literacy in Non-Literary Papyri from Graeco-Roman Egypt: Further Aspects of the Educational Ideal in Ancient Literary Sources and Modern Times". Mnemosyme. 53 (3): 322–342 (325–327). doi:10.1163/156852500510633. JSTOR 4433101.
 +
Peachin, pp. 89, 97–98.
 +
Mattern, Susan P. (1999) Rome and the Enemy: Imperial Strategy in the Principate. University of California Press. p. 197
 +
Morgan, Teresa (1998) Literate Education in the Hellenistic and Roman Worlds. Cambridge University Press. pp. 1–2
 +
Johnson (2009), pp. 46ff.
 +
Peachin, p. 97.
 +
Clifford Ando poses the question as "what good would 'posted edicts' do in a world of low literacy?' in Ando, p. 101 (see also p. 87 on "the government's obsessive documentation").
 +
Ando, pp. 86–87.
 +
Ando, p. 101
 +
Ando, pp. 152, 210.
 +
Beard, Mary (1991) "Ancient Literacy and the Written Word in Roman Religion," in Literacy in the Roman World. University of Michigan Press. p. 59ff
 +
Dickie, Matthew (2001) Magic and Magicians in the Greco-Roman World. Routledge. pp. pp. 94–95, 181–182, and 196
 +
Potter (2009), p. 555
 +
Harris, pp. 29, 218–219.
 +
Phang, Sara Elise (2011) "Military Documents, Languages, and Literacy," in A Companion to the Roman Army. Blackwell. pp. 286–301.
 +
Mattern, Rome and the Enemy, p. 197, citing Harris, pp. 253–255.
 +
Harris, pp. 9, 48, 215, 248, 258–269
 +
Johnson (2009), pp. 47, 54, 290ff.
 +
Mattern, Rome and the Enemy, p. 197
 +
Gagarin, pp. 19–20.
 +
Johnson (2010), pp. 17–18.
 +
Martial, Epigrams 1.2 and 14.184–92, as cited by Johnson (2010), p. 17
 +
Cavallo, pp. 83–84.
 +
Cavallo, pp. 84–85.
 +
Cavallo, p. 84.
 +
Marshall, p. 253.
 +
Cavallo, p. 71
 +
Marshall, p. 253, citing on the book trade in the provinces Pliny the Younger, Epistulae 9.11.2; Martial, Epigrams 7.88; Horace, Carmina 2.20.13f. and Ars Poetica 345; Ovid, Tristia 4.9.21 and 4.10.128; Pliny the Elder, Natural History 35.2.11; Sidonius, Epistulae 9.7.1.
 +
Strabo 13.1.54, 50.13.419; Martial, Epigrams 2.8; Lucian, Adversus Indoctum 1
 +
According to Seneca, Epistulae 27.6f.
 +
Marshall, p. 254.
 +
Marshall, pp. 252–264.
 +
Cavallo, pp. 67–68.
 +
Marshall, pp. 257, 260.
 +
Pliny, Epistulae 1.8.2; CIL 5.5262 (= ILS 2927)
 +
Marshall, p. 255.
 +
Marshall, 261–262
 +
Cavallo, p. 70.
 +
Tacitus, Agricola 2.1 and Annales 4.35 and 14.50; Pliny the Younger, Epistulae 7.19.6; Suetonius, Augustus 31, Tiberius 61.3, and Caligula 16
 +
Suetonius, Domitian 10; Quintilian, Institutio Oratoria 9.2.65
 +
Marshall, p. 263.
 +
Johnson (2009), pp. 114ff., pp. 186ff.
 +
Potter (2009), p. 372.
 +
Johnson (2010) p. 14.
 +
Johnson (2009), pp. 320ff.
 +
Cavallo, pp. 68–69, 78–79.
 +
Cavallo, pp. 81–82.
 +
Peachin, p. 95.
 +
Peachin, pp. 84–85.
 +
Laes, p. 108
 +
Peachin, p. 89.
 +
Laes, pp. 113–116.
 +
Peachin, pp. 90, 92
 +
Laes, pp. 116–121.
 +
Peachin, pp. 87–89.
 +
Laes, p. 122.
 +
Peachin, p. 90.
 +
Laes, pp. 107–108, 132.
 +
Peachin, pp. 93–94.
 +
Peachin, pp. 88, 106
 +
Laes, p. 109.
 +
Laes, p. 132.
 +
Potter (2009), pp. 439, 442.
 +
Peachin, pp. 102–103, 105.
 +
Peachin, pp. 104–105.
 +
Peachin, pp. 103, 106.
 +
Peachin, p. 110.
 +
Peachin, p. 107.
 +
Harris, p. 5.
 +
Saller, R. P. (2012). "Promotion and Patronage in Equestrian Careers". Journal of Roman Studies. 70: 44. doi:10.2307/299555. JSTOR 299555.
 +
Armstron, David (2010) "The Biographical and Social Foundations of Horace's Poetic Voice," in A Companion to Horace. Blackwell. p. 11
 +
Lyne, R.O.A.M. (1995) Horace: Beyond the Public Poetry. Yale University Press. pp. 2–3
 +
Peachin, p. 94.
 +
Potter (2009), p. 598.
 +
Laes, pp. 109–110.
 +
Peachin, p. 88.
 +
Laes, p. 110
 +
Gagarin, p. 19.
 +
Gagarin, p. 18.
 +
The wide-ranging 21st-century scholarship on the Second Sophistic includes Being Greek under Rome: Cultural Identity, the Second Sophistic and the Development of Empire, edited by Simon Goldhill (Cambridge University Press, 2001); Paideia: The World of the Second Sophistic, edited by Barbara E. Borg (De Gruyter, 2004); and Tim Whitmarsh, The Second Sophistic (Oxford University Press, 2005).
 +
Habinek, Thomas N. (1998) The Politics of Latin Literature: Writing, Identity, and Empire in Ancient Rome. Princeton University Press. pp. 122–123
 +
Rawson (2003), p. 80.
 +
James, Sharon L. (2003) Learned Girls and Male Persuasion: Gender and Reading in Roman Love Elegy. University of California Press. pp. 21–25
 +
Johnson, W.R. "Propertius," pp. 42–43, and Sharon L. James, "Elegy and New Comedy," p. 262, both in A Companion to Roman Love Elegy. Blackwell, 2012.
 +
Gagarin, p. 20.
 +
Harris, p. 3.
 +
Numbers, Ronald (2009). Galileo Goes to Jail and Other Myths about Science and Religion. Harvard University Press. p. 18. ISBN 978-0-674-03327-6.
 +
Grant, Edvard. (1996) “The Foundations of Modern Science in the Middle Ages. Cambridge University Press. Page 4.
 +
Cavallo, pp. 87–89.
 +
Cavallo, p. 86.
 +
Cavallo, p. 15-16.
 +
Roberts, p. 3.
 +
Aetas Ovidiana; Charles McNelis, "Ovidian Strategies in Early Imperial Literature," in A Companion to Ovid (Blackwell, 2007), p. 397.
 +
Roberts, p. 8.
 +
van Dam, Harm-Jan (2008) "Wandering Woods Again: From Poliziano to Grotius," in The Poetry of Statius. Brill. p. 45ff.
 +
Jonathan Master, "The Histories," in A Companion to Tacitus (Blackwell, 2012), p. 88.
 +
Sage, Michael M. (1990) "Tacitus' Historical Works: A Survey and Appraisal," Aufstieg und Niedergang der römischen Welt II.33.2, p. 853.
 +
Albrecht, p. 1294.
 +
Albrecht, p. 1443.
 +
Roberts, p. 70.
 +
Albrecht, p. 1359ff.
 +
"Not since Vergil had there been a Roman poet so effective at establishing a master narrative for his people": Marc Mastrangelo, The Roman Self in Late Antiquity: Prudentius and the Poetics of the Soul (Johns Hopkins University Press, 2008), p. 3.
 +
Bowersock, p. 694
 +
Rüpke, p. 4.
 +
Apuleius, Florides 1.1
 +
Rüpke, p. 279.
 +
Matthew Bunson, A Dictionary of the Roman Empire (Oxford University Press, 1995), p. 246.
 +
The caesareum at Najaran was possibly known later as the "Kaaba of Najran": جواد علي, المفصل في تاريخ العرب قبل الإسلام (Jawad Ali, Al-Mufassal fi Tarikh Al-'Arab Qabl Al-Islam; "Commentary on the History of the Arabs Before Islam"), Baghdad, 1955–1983; P. Harland, "Imperial Cults within Local Cultural Life: Associations in Roman Asia", originally published in Ancient History Bulletin / Zeitschrift für Alte Geschichte 17 (2003) 91–103.
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Isaac, Benjamin H. (2004) The Invention of Racism in Classical Antiquity. Princeton University Press. p. 449
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Frend, W.H.C. (1967) Martyrdom and Persecution in the Early Church: A Study of Conflict from the Maccabees to Donatus. Doubleday. p. 106
 +
Huskinson, Janet (2000) Experiencing Rome: Culture, Identity and Power in the Roman Empire. Routledge. p. 261. See, for instance, the altar dedicated by a Roman citizen and depicting a sacrifice conducted in the Roman manner for the Germanic goddess Vagdavercustis in the 2nd century AD.
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Momigliano, Arnaldo (1986). "The Disadvantages of Monotheism for a Universal State". Classical Philology. 81 (4): 285–297. doi:10.1086/367003. JSTOR 269977.
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Fishwick, Duncan (1991). The Imperial Cult in the Latin West: Studies in the Ruler Cult of the Western Provinces of the Roman Empire, Vol. 1, Brill. pp. 97–149. ISBN 90-04-07179-2.
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Ben-Sasson, H.H. (1976) A History of the Jewish People, Harvard University Press. pp. 254–256. ISBN 0-674-39731-2
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Bowman, p. 616
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Frend, W.H.C. (2006) "Persecutions: Genesis and Legacy," Cambridge History of Christianity: Origins to Constantine. Cambridge University Press. Vol. 1, p. 510. ISBN 0521812399.
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Barnes, T. D. (2012). "Legislation against the Christians". Journal of Roman Studies. 58: 32. doi:10.2307/299693. JSTOR 299693.
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Sainte-Croix, G.E.M de (1963). "Why Were the Early Christians Persecuted?". Past & Present. 26: 6–38. doi:10.1093/past/26.1.6.
 +
Musurillo, Herbert (1972) The Acts of the Christian Martyrs. Oxford: Clarendon Press. pp. lviii–lxii
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Sherwin-White, A. N. (1952). "The Early Persecutions and Roman Law Again". The Journal of Theological Studies (2): 199. doi:10.1093/jts/III.2.199. JSTOR 23952852.
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Tacitus, Annals XV.44
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Eusebius of Caesarea (425). Church History.
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Smallwood, E.M. (1956). "'Domitian's attitude towards the Jews and Judaism". Classical Philology. 51: 1–13. doi:10.1086/363978.
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Pliny, Epistle to Trajan on the Christians
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Frend, W. H. C. (1959). "The Failure of the Persecutions in the Roman Empire". Past and Present. 16: 10. doi:10.1093/past/16.1.10. JSTOR 650151.
 +
Bowersock, p. 625
 +
Rüpke, pp. 406–426
 +
On vocabulary, see Schilling, Robert (1992) "The Decline and Survival of Roman Religion", Roman and European Mythologies. University of Chicago Press. p. 110.
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Burgan, Michael (2009). Empire of Ancient Rome. Infobase Publishing. pp. 113–114. ISBN 978-1-4381-2659-3.
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Noble, Thomas F. X.; Strauss, Barry; Osheim, Duane J.; Neuschel, Kristen B.; Accampo, Elinor Ann (2010). Western Civilization: Beyond Boundaries, 1300–1815. Cengage Learning. p. 352. ISBN 978-1-4240-6959-0.
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Goffman, Daniel (2002). The Ottoman Empire and Early Modern Europe. Cambridge University Press. p. 107.
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Encyclopædia Britannica, History of Europe, The Romans, 2008, O.Ed.
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Collier, Martin (2003). Italian Unification, 1820–71. Heinemann. p. 22. ISBN 0-435-32754-2.
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Briggs, Ward (2010) "United States," in A Companion to the Classical Tradition. Blackwell. p. 279ff.
 +
Meinig, D.W. (1986) The Shaping of America: A Geographical Perspective on 500 Years of History. Atlantic America, 1492–1800. Yale University Press. Vol. 1. pp. 432–435. ISBN 0300038828.
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Vale, Lawrence J. (1992) Architecture, Power, and National Identity. Yale University Press. pp. 11, 66–67
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Mallgrave, Harry Francis (2005) Modern Architectural Theory: A Historical Survey, 1673–1968. Cambridge University Press. pp. 144–145
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Kornwall, James D. (2011) Architecture and Town Planning in Colonial North America. Johns Hopkins University Press, vol. 3. pp. 1246, 1405–1408. ISBN 0801859867.
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Wood, pp. 73–74
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Onuf, Peter S. and Cole, Nicholas P. introduction to Thomas Jefferson, the Classical World, and Early America. University of Virginia Press. p. 5
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Dietler, Michael (2010). Archaeologies of Colonialism: Consumption, Entanglement, and Violence in Ancient Mediterranean France. University of California Press. ISBN 978-0-520-26551-6.
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Briggs, W. (2010) "United States," in A Companion to the Classical Tradition. Blackwell. pp. 282–286
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Wood, pp. 60, 66, 73–74, 239.
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Gelernter, Mark (1999) A History of American Architecture: Buildings in Their Cultural and Technological Context. University Press of New England. p. 13.
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Wilson, Richard Guy (2011) "Thomas Jefferson's Classical Architecture: An American Agenda," in Thomas Jefferson, the Classical World, and Early America. University of Virginia Press. p. 122
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Spahn, Hannah (2011) Thomas Jefferson, Time, and History. University of Virginia Press. pp. 144–145, 163–167
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Wood, pp. 228–330
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Lears, Jackson (2009) Rebirth of a Nation: The Making of Modern America, 1877–1920. HarperCollins. pp. 277–278
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Gutheim, Frederick and Lee, Antoinette J. (2006) Worthy of the Nation: Washington, DC, from L'Enfant to the National Capital Planning Committee. Johns Hopkins University Press, 2nd ed. pp. 137, 152.
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External links
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This article is about the chemical element and its most stable form, O
 +
2. For other forms of this element, see Allotropes of oxygen. For other uses, see Oxygen (disambiguation) and O2 (disambiguation).
 +
Oxygen,  8O
 +
A transparent beaker containing a light blue fluid with gas bubbles
 +
Liquid oxygen boiling
 +
Oxygen
 +
Allotropes O2, O3 (Ozone)
 +
Appearance gas: colorless
 +
liquid: pale blue
 +
Standard atomic weight Ar, std(O) [15.99903, 15.99977] conventional: 15.999
 +
Oxygen in the periodic table
 +
Hydrogen
 +
Helium
 +
Lithium
 +
Beryllium
 +
Boron
 +
Carbon
 +
Nitrogen
 +
Oxygen
 +
Fluorine
 +
Neon
 +
Sodium
 +
Magnesium
 +
Aluminium
 +
Silicon
 +
Phosphorus
 +
Sulfur
 +
Chlorine
 +
Argon
 +
Potassium
 +
Calcium
 +
Scandium
 +
Titanium
 +
Vanadium
 +
Chromium
 +
Manganese
 +
Iron
 +
Cobalt
 +
Nickel
 +
Copper
 +
Zinc
 +
Gallium
 +
Germanium
 +
Arsenic
 +
Selenium
 +
Bromine
 +
Krypton
 +
Rubidium
 +
Strontium
 +
Yttrium
 +
Zirconium
 +
Niobium
 +
Molybdenum
 +
Technetium
 +
Ruthenium
 +
Rhodium
 +
Palladium
 +
Silver
 +
Cadmium
 +
Indium
 +
Tin
 +
Antimony
 +
Tellurium
 +
Iodine
 +
Xenon
 +
Caesium
 +
Barium
 +
Lanthanum
 +
Cerium
 +
Praseodymium
 +
Neodymium
 +
Promethium
 +
Samarium
 +
Europium
 +
Gadolinium
 +
Terbium
 +
Dysprosium
 +
Holmium
 +
Erbium
 +
Thulium
 +
Ytterbium
 +
Lutetium
 +
Hafnium
 +
Tantalum
 +
Tungsten
 +
Rhenium
 +
Osmium
 +
Iridium
 +
Platinum
 +
Gold
 +
Mercury (element)
 +
Thallium
 +
Lead
 +
Bismuth
 +
Polonium
 +
Astatine
 +
Radon
 +
Francium
 +
Radium
 +
Actinium
 +
Thorium
 +
Protactinium
 +
Uranium
 +
Neptunium
 +
Plutonium
 +
Americium
 +
Curium
 +
Berkelium
 +
Californium
 +
Einsteinium
 +
Fermium
 +
Mendelevium
 +
Nobelium
 +
Lawrencium
 +
Rutherfordium
 +
Dubnium
 +
Seaborgium
 +
Bohrium
 +
Hassium
 +
Meitnerium
 +
Darmstadtium
 +
Roentgenium
 +
Copernicium
 +
Nihonium
 +
Flerovium
 +
Moscovium
 +
Livermorium
 +
Tennessine
 +
Oganesson
 +
 +
 +
O
 +
 +
S
 +
nitrogen ← oxygen → fluorine
 +
Atomic number (Z) 8
 +
Group group 16 (chalcogens)
 +
Period period 2
 +
Block p-block
 +
Element category   reactive nonmetal
 +
Electron configuration [He] 2s2 2p4
 +
Electrons per shell
 +
2, 6
 +
Physical properties
 +
Phase at STP gas
 +
Melting point 54.36 K ​(−218.79 °C, ​−361.82 °F)
 +
Boiling point 90.188 K ​(−182.962 °C, ​−297.332 °F)
 +
Density (at STP) 1.429 g/L
 +
when liquid (at b.p.) 1.141 g/cm3
 +
Triple point 54.361 K, ​0.1463 kPa
 +
Critical point 154.581 K, 5.043 MPa
 +
Heat of fusion (O2) 0.444 kJ/mol
 +
Heat of vaporization (O2) 6.82 kJ/mol
 +
Molar heat capacity (O2) 29.378 J/(mol·K)
 +
Vapor pressure
 +
P (Pa) 1 10 100 1 k 10 k 100 k
 +
at T (K) 61 73 90
 +
Atomic properties
 +
Oxidation states −2, −1, +1, +2
 +
Electronegativity Pauling scale: 3.44
 +
Ionization energies
 +
1st: 1313.9 kJ/mol
 +
2nd: 3388.3 kJ/mol
 +
3rd: 5300.5 kJ/mol
 +
(more)
 +
Covalent radius 66±2 pm
 +
Van der Waals radius 152 pm
 +
Color lines in a spectral range
 +
Spectral lines of oxygen
 +
Other properties
 +
Natural occurrence primordial
 +
Crystal structure ​cubicCubic crystal structure for oxygen
 +
Speed of sound 330 m/s (gas, at 27 °C)
 +
Thermal conductivity 26.58×10−3  W/(m·K)
 +
Magnetic ordering paramagnetic
 +
Magnetic susceptibility +3449.0·10−6 cm3/mol (293 K)[1]
 +
CAS Number 7782-44-7
 +
History
 +
Discovery Carl Wilhelm Scheele (1771)
 +
Named by Antoine Lavoisier (1777)
 +
Main isotopes of oxygen
 +
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
 +
16O 99.76% stable
 +
17O 0.04% stable
 +
18O 0.20% stable
 +
viewtalkedit | references
 +
Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium. At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O
 +
2. Diatomic oxygen gas constitutes 20.8% of the Earth's atmosphere. As compounds including oxides, the element makes up almost half of the Earth's crust.
 +
 
 +
Dioxygen is used in cellular respiration and many major classes of organic molecules in living organisms contain oxygen, such as proteins, nucleic acids, carbohydrates, and fats, as do the major constituent inorganic compounds of animal shells, teeth, and bone. Most of the mass of living organisms is oxygen as a component of water, the major constituent of lifeforms. Oxygen is continuously replenished in Earth's atmosphere by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form (allotrope) of oxygen, ozone (O
 +
3), strongly absorbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation. However, ozone present at the surface is a byproduct of smog and thus a pollutant.
 +
 
 +
Oxygen was isolated by Michael Sendivogius before 1604, but it is commonly believed that the element was discovered independently by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, and Joseph Priestley in Wiltshire, in 1774. Priority is often given for Priestley because his work was published first. Priestley, however, called oxygen "dephlogisticated air", and did not recognize it as a chemical element. The name oxygen was coined in 1777 by Antoine Lavoisier, who first recognized oxygen as a chemical element and correctly characterized the role it plays in combustion.
 +
 
 +
Common uses of oxygen include production of steel, plastics and textiles, brazing, welding and cutting of steels and other metals, rocket propellant, oxygen therapy, and life support systems in aircraft, submarines, spaceflight and diving.
 +
 
 +
 
 +
Contents
 +
1 History
 +
1.1 Early experiments
 +
1.2 Phlogiston theory
 +
1.3 Discovery
 +
1.4 Lavoisier's contribution
 +
1.5 Later history
 +
2 Characteristics
 +
2.1 Properties and molecular structure
 +
2.2 Allotropes
 +
2.3 Physical properties
 +
2.4 Isotopes and stellar origin
 +
2.5 Occurrence
 +
2.6 Analysis
 +
3 Biological role of O2
 +
3.1 Photosynthesis and respiration
 +
3.2 Living organisms
 +
3.3 Build-up in the atmosphere
 +
4 Industrial production
 +
5 Storage
 +
6 Applications
 +
6.1 Medical
 +
6.2 Life support and recreational use
 +
6.3 Industrial
 +
7 Compounds
 +
7.1 Oxides and other inorganic compounds
 +
7.2 Organic compounds
 +
8 Safety and precautions
 +
8.1 Toxicity
 +
8.2 Combustion and other hazards
 +
9 See also
 +
10 Notes
 +
11 References
 +
11.1 General references
 +
12 External links
 +
History
 +
Early experiments
 +
One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle and surrounding the vessel's neck with water resulted in some water rising into the neck.[2] Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philo's work by observing that a portion of air is consumed during combustion and respiration.[3]
 +
 
 +
In the late 17th century, Robert Boyle proved that air is necessary for combustion. English chemist John Mayow (1641–1679) refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus.[4] In one experiment, he found that placing either a mouse or a lit candle in a closed container over water caused the water to rise and replace one-fourteenth of the air's volume before extinguishing the subjects.[5] From this he surmised that nitroaereus is consumed in both respiration and combustion.
 +
 
 +
Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it.[4] He also thought that the lungs separate nitroaereus from air and pass it into the blood and that animal heat and muscle movement result from the reaction of nitroaereus with certain substances in the body.[4] Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract "De respiratione".[5]
 +
 
 +
Phlogiston theory
 +
Main article: Phlogiston theory
 +
Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element.[6] This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes.[7]
 +
 
 +
Established in 1667 by the German alchemist J. J. Becher, and modified by the chemist Georg Ernst Stahl by 1731,[8] phlogiston theory stated that all combustible materials were made of two parts. One part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx.[3]
 +
 
 +
Highly combustible materials that leave little residue, such as wood or coal, were thought to be made mostly of phlogiston; non-combustible substances that corrode, such as iron, contained very little. Air did not play a role in phlogiston theory, nor were any initial quantitative experiments conducted to test the idea; instead, it was based on observations of what happens when something burns, that most common objects appear to become lighter and seem to lose something in the process.[3]
 +
 
 +
Discovery
 +
A drawing of an elderly man sitting by a table and facing parallel to the drawing. His left arm rests on a notebook, legs crossed.
 +
Joseph Priestley is usually given priority in the discovery.
 +
Polish alchemist, philosopher, and physician Michael Sendivogius in his work De Lapide Philosophorum Tractatus duodecim e naturae fonte et manuali experientia depromti (1604) described a substance contained in air, referring to it as 'cibus vitae' (food of life[9]), and this substance is identical with oxygen.[10] Sendivogius, during his experiments performed between 1598 and 1604, properly recognized that the substance is equivalent to the gaseous byproduct released by the thermal decomposition of potassium nitrate. In Bugaj’s view, the isolation of oxygen and the proper association of the substance to that part of air which is required for life, lends sufficient weight to the discovery of oxygen by Sendivogius.[10] This discovery of Sendivogius was however frequently denied by the generations of scientists and chemists which succeeded him.[9]
 +
 
 +
It is also commonly claimed that oxygen was first discovered by Swedish pharmacist Carl Wilhelm Scheele. He had produced oxygen gas by heating mercuric oxide and various nitrates in 1771–2.[11][12][3] Scheele called the gas "fire air" because it was then the only known agent to support combustion. He wrote an account of this discovery in a manuscript titled Treatise on Air and Fire, which he sent to his publisher in 1775. That document was published in 1777.[13]
 +
 
 +
In the meantime, on August 1, 1774, an experiment conducted by the British clergyman Joseph Priestley focused sunlight on mercuric oxide (HgO) contained in a glass tube, which liberated a gas he named "dephlogisticated air".[12] He noted that candles burned brighter in the gas and that a mouse was more active and lived longer while breathing it. After breathing the gas himself, Priestley wrote: "The feeling of it to my lungs was not sensibly different from that of common air, but I fancied that my breast felt peculiarly light and easy for some time afterwards."[6] Priestley published his findings in 1775 in a paper titled "An Account of Further Discoveries in Air," which was included in the second volume of his book titled Experiments and Observations on Different Kinds of Air.[3][14] Because he published his findings first, Priestley is usually given priority in the discovery.
 +
 
 +
The French chemist Antoine Laurent Lavoisier later claimed to have discovered the new substance independently. Priestley visited Lavoisier in October 1774 and told him about his experiment and how he liberated the new gas. Scheele also dispatched a letter to Lavoisier on September 30, 1774, that described his discovery of the previously unknown substance, but Lavoisier never acknowledged receiving it (a copy of the letter was found in Scheele's belongings after his death).[13]
 +
 
 +
Lavoisier's contribution
 +
Lavoisier conducted the first adequate quantitative experiments on oxidation and gave the first correct explanation of how combustion works.[12] He used these and similar experiments, all started in 1774, to discredit the phlogiston theory and to prove that the substance discovered by Priestley and Scheele was a chemical element.
 +
 
 +
A drawing of a young man facing towards the viewer, but looking on the side. He wear a white curly wig, dark suit and white scarf.
 +
Antoine Lavoisier discredited the phlogiston theory.
 +
In one experiment, Lavoisier observed that there was no overall increase in weight when tin and air were heated in a closed container.[12] He noted that air rushed in when he opened the container, which indicated that part of the trapped air had been consumed. He also noted that the tin had increased in weight and that increase was the same as the weight of the air that rushed back in. This and other experiments on combustion were documented in his book Sur la combustion en général, which was published in 1777.[12] In that work, he proved that air is a mixture of two gases; 'vital air', which is essential to combustion and respiration, and azote (Gk. ἄζωτον "lifeless"), which did not support either. Azote later became nitrogen in English, although it has kept the earlier name in French and several other European languages.[12]
 +
 
 +
Lavoisier renamed 'vital air' to oxygène in 1777 from the Greek roots ὀξύς (oxys) (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter), because he mistakenly believed that oxygen was a constituent of all acids.[15] Chemists (such as Sir Humphry Davy in 1812) eventually determined that Lavoisier was wrong in this regard (hydrogen forms the basis for acid chemistry), but by then the name was too well established.[16]
 +
 
 +
Oxygen entered the English language despite opposition by English scientists and the fact that the Englishman Priestley had first isolated the gas and written about it. This is partly due to a poem praising the gas titled "Oxygen" in the popular book The Botanic Garden (1791) by Erasmus Darwin, grandfather of Charles Darwin.[13]
 +
 
 +
Later history
 +
A metal frame structure stands on the snow near a tree. A middle-aged man wearing a coat, boots, leather gloves and a cap stands by the structure and holds it with his right hand.
 +
Robert H. Goddard and a liquid oxygen-gasoline rocket
 +
John Dalton's original atomic hypothesis presumed that all elements were monatomic and that the atoms in compounds would normally have the simplest atomic ratios with respect to one another. For example, Dalton assumed that water's formula was HO, leading to the conclusion that the atomic mass of oxygen was 8 times that of hydrogen, instead of the modern value of about 16.[17] In 1805, Joseph Louis Gay-Lussac and Alexander von Humboldt showed that water is formed of two volumes of hydrogen and one volume of oxygen; and by 1811 Amedeo Avogadro had arrived at the correct interpretation of water's composition, based on what is now called Avogadro's law and the diatomic elemental molecules in those gases.[18][a]
 +
 
 +
By the late 19th century scientists realized that air could be liquefied and its components isolated by compressing and cooling it. Using a cascade method, Swiss chemist and physicist Raoul Pierre Pictet evaporated liquid sulfur dioxide in order to liquefy carbon dioxide, which in turn was evaporated to cool oxygen gas enough to liquefy it. He sent a telegram on December 22, 1877 to the French Academy of Sciences in Paris announcing his discovery of liquid oxygen.[19] Just two days later, French physicist Louis Paul Cailletet announced his own method of liquefying molecular oxygen.[19] Only a few drops of the liquid were produced in each case and no meaningful analysis could be conducted. Oxygen was liquefied in a stable state for the first time on March 29, 1883 by Polish scientists from Jagiellonian University, Zygmunt Wróblewski and Karol Olszewski.[20]
 +
 
 +
In 1891 Scottish chemist James Dewar was able to produce enough liquid oxygen for study.[21] The first commercially viable process for producing liquid oxygen was independently developed in 1895 by German engineer Carl von Linde and British engineer William Hampson. Both men lowered the temperature of air until it liquefied and then distilled the component gases by boiling them off one at a time and capturing them separately.[22] Later, in 1901, oxyacetylene welding was demonstrated for the first time by burning a mixture of acetylene and compressed O
 +
2. This method of welding and cutting metal later became common.[22]
 +
 
 +
In 1923, the American scientist Robert H. Goddard became the first person to develop a rocket engine that burned liquid fuel; the engine used gasoline for fuel and liquid oxygen as the oxidizer. Goddard successfully flew a small liquid-fueled rocket 56 m at 97 km/h on March 16, 1926 in Auburn, Massachusetts, US.[22][23]
 +
 
 +
Oxygen levels in the atmosphere are trending slightly downward globally, possibly because of fossil-fuel burning.[24]
 +
 
 +
Characteristics
 +
Properties and molecular structure
 +
 
 +
Orbital diagram, after Barrett (2002),[25] showing the participating atomic orbitals from each oxygen atom, the molecular orbitals that result from their overlap, and the aufbau filling of the orbitals with the 12 electrons, 6 from each O atom, beginning from the lowest energy orbitals, and resulting in covalent double bond character from filled orbitals (and cancellation of the contributions of the pairs of σ and σ* and π and π* orbital pairs).
 +
At standard temperature and pressure, oxygen is a colorless, odorless, and tasteless gas with the molecular formula O
 +
2, referred to as dioxygen.[26]
 +
 
 +
As dioxygen, two oxygen atoms are chemically bound to each other. The bond can be variously described based on level of theory, but is reasonably and simply described as a covalent double bond that results from the filling of molecular orbitals formed from the atomic orbitals of the individual oxygen atoms, the filling of which results in a bond order of two. More specifically, the double bond is the result of sequential, low-to-high energy, or Aufbau, filling of orbitals, and the resulting cancellation of contributions from the 2s electrons, after sequential filling of the low σ and σ* orbitals; σ overlap of the two atomic 2p orbitals that lie along the O-O molecular axis and π overlap of two pairs of atomic 2p orbitals perpendicular to the O-O molecular axis, and then cancellation of contributions from the remaining two of the six 2p electrons after their partial filling of the lowest π and π* orbitals.[25]
 +
 
 +
This combination of cancellations and σ and π overlaps results in dioxygen's double bond character and reactivity, and a triplet electronic ground state. An electron configuration with two unpaired electrons, as is found in dioxygen orbitals (see the filled π* orbitals in the diagram) that are of equal energy—i.e., degenerate—is a configuration termed a spin triplet state. Hence, the ground state of the O
 +
2 molecule is referred to as triplet oxygen.[27][b] The highest energy, partially filled orbitals are antibonding, and so their filling weakens the bond order from three to two. Because of its unpaired electrons, triplet oxygen reacts only slowly with most organic molecules, which have paired electron spins; this prevents spontaneous combustion.[28]
 +
 
 +
 
 +
Liquid oxygen, temporarily suspended in a magnet owing to its paramagnetism
 +
In the triplet form, O
 +
2 molecules are paramagnetic. That is, they impart magnetic character to oxygen when it is in the presence of a magnetic field, because of the spin magnetic moments of the unpaired electrons in the molecule, and the negative exchange energy between neighboring O
 +
2 molecules.[21] Liquid oxygen is so magnetic that, in laboratory demonstrations, a bridge of liquid oxygen may be supported against its own weight between the poles of a powerful magnet.[29][c]
 +
 
 +
Singlet oxygen is a name given to several higher-energy species of molecular O
 +
2 in which all the electron spins are paired. It is much more reactive with common organic molecules than is molecular oxygen per se. In nature, singlet oxygen is commonly formed from water during photosynthesis, using the energy of sunlight.[30] It is also produced in the troposphere by the photolysis of ozone by light of short wavelength,[31] and by the immune system as a source of active oxygen.[32] Carotenoids in photosynthetic organisms (and possibly animals) play a major role in absorbing energy from singlet oxygen and converting it to the unexcited ground state before it can cause harm to tissues.[33]
 +
 
 +
Allotropes
 +
Main article: Allotropes of oxygen
 +
 
 +
Space-filling model representation of dioxygen (O2) molecule
 +
The common allotrope of elemental oxygen on Earth is called dioxygen, O
 +
2, the major part of the Earth's atmospheric oxygen (see Occurrence). O2 has a bond length of 121 pm and a bond energy of 498 kJ/mol,[34] which is smaller than the energy of other double bonds or pairs of single bonds in the biosphere and responsible for the exothermic reaction of O2 with any organic molecule.[28][35] Due to its energy content, O2 is used by complex forms of life, such as animals, in cellular respiration. Other aspects of O
 +
2 are covered in the remainder of this article.
 +
 
 +
Trioxygen (O
 +
3) is usually known as ozone and is a very reactive allotrope of oxygen that is damaging to lung tissue.[36] Ozone is produced in the upper atmosphere when O
 +
2 combines with atomic oxygen made by the splitting of O
 +
2 by ultraviolet (UV) radiation.[15] Since ozone absorbs strongly in the UV region of the spectrum, the ozone layer of the upper atmosphere functions as a protective radiation shield for the planet.[15] Near the Earth's surface, it is a pollutant formed as a by-product of automobile exhaust.[36] At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft.[37]
 +
 
 +
The metastable molecule tetraoxygen (O
 +
4) was discovered in 2001,[38][39] and was assumed to exist in one of the six phases of solid oxygen. It was proven in 2006 that this phase, created by pressurizing O
 +
2 to 20 GPa, is in fact a rhombohedral O
 +
8 cluster.[40] This cluster has the potential to be a much more powerful oxidizer than either O
 +
2 or O
 +
3 and may therefore be used in rocket fuel.[38][39] A metallic phase was discovered in 1990 when solid oxygen is subjected to a pressure of above 96 GPa[41] and it was shown in 1998 that at very low temperatures, this phase becomes superconducting.[42]
 +
 
 +
Physical properties
 +
 
 +
Oxygen discharge (spectrum) tube
 +
See also: Liquid oxygen and solid oxygen
 +
Oxygen dissolves more readily in water than nitrogen, and in freshwater more readily than seawater. Water in equilibrium with air contains approximately 1 molecule of dissolved O
 +
2 for every 2 molecules of N
 +
2 (1:2), compared with an atmospheric ratio of approximately 1:4. The solubility of oxygen in water is temperature-dependent, and about twice as much (14.6 mg·L−1) dissolves at 0 °C than at 20 °C (7.6 mg·L−1).[6][43] At 25 °C and 1 standard atmosphere (101.3 kPa) of air, freshwater contains about 6.04 milliliters (mL) of oxygen per liter, and seawater contains about 4.95 mL per liter.[44] At 5 °C the solubility increases to 9.0 mL (50% more than at 25 °C) per liter for water and 7.2 mL (45% more) per liter for sea water.
 +
 
 +
Oxygen gas dissolved in water at sea-level
 +
5 °C 25 °C
 +
Freshwater 9.0 mL 6.04 mL
 +
Seawater 7.2 mL 4.95 mL
 +
Oxygen condenses at 90.20 K (−182.95 °C, −297.31 °F), and freezes at 54.36 K (−218.79 °C, −361.82 °F).[45] Both liquid and solid O
 +
2 are clear substances with a light sky-blue color caused by absorption in the red (in contrast with the blue color of the sky, which is due to Rayleigh scattering of blue light). High-purity liquid O
 +
2 is usually obtained by the fractional distillation of liquefied air.[46] Liquid oxygen may also be condensed from air using liquid nitrogen as a coolant.[47]
 +
 
 +
Oxygen is a highly reactive substance and must be segregated from combustible materials.[47]
 +
 
 +
The spectroscopy of molecular oxygen is associated with the atmospheric processes of aurora and airglow.[48] The absorption in the Herzberg continuum and Schumann–Runge bands in the ultraviolet produces atomic oxygen that is important in the chemistry of the middle atmosphere.[49] Excited state singlet molecular oxygen is responsible for red chemiluminescence in solution.[50]
 +
 
 +
Isotopes and stellar origin
 +
Main article: Isotopes of oxygen
 +
A concentric-sphere diagram, showing, from the core to the outer shell, iron, silicon, oxygen, neon, carbon, helium and hydrogen layers.
 +
Late in a massive star's life, 16O concentrates in the O-shell, 17O in the H-shell and 18O in the He-shell.
 +
Naturally occurring oxygen is composed of three stable isotopes, 16O, 17O, and 18O, with 16O being the most abundant (99.762% natural abundance).[51]
 +
 
 +
Most 16O is synthesized at the end of the helium fusion process in massive stars but some is made in the neon burning process.[52] 17O is primarily made by the burning of hydrogen into helium during the CNO cycle, making it a common isotope in the hydrogen burning zones of stars.[52] Most 18O is produced when 14N (made abundant from CNO burning) captures a 4He nucleus, making 18O common in the helium-rich zones of evolved, massive stars.[52]
 +
 
 +
Fourteen radioisotopes have been characterized. The most stable are 15O with a half-life of 122.24 seconds and 14O with a half-life of 70.606 seconds.[51] All of the remaining radioactive isotopes have half-lives that are less than 27 s and the majority of these have half-lives that are less than 83 milliseconds.[51] The most common decay mode of the isotopes lighter than 16O is β+ decay[53][54][55] to yield nitrogen, and the most common mode for the isotopes heavier than 18O is beta decay to yield fluorine.[51]
 +
 
 +
Occurrence
 +
See also: Silicate minerals, Category:Oxide minerals, Stellar population, Cosmochemistry, and Astrochemistry
 +
Ten most common elements in the Milky Way Galaxy estimated spectroscopically[56]
 +
Z Element Mass fraction in parts per million
 +
1 Hydrogen 739,000 71 × mass of oxygen (red bar)
 +
2 Helium 240,000 23 × mass of oxygen (red bar)
 +
8 Oxygen 10,400
 +
 +
6 Carbon 4,600
 +
 +
10 Neon 1,340
 +
 +
26 Iron 1,090
 +
 +
7 Nitrogen 960
 +
 +
14 Silicon 650
 +
 +
12 Magnesium 580
 +
 +
16 Sulfur 440
 +
 +
Oxygen is the most abundant chemical element by mass in the Earth's biosphere, air, sea and land. Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium.[57] About 0.9% of the Sun's mass is oxygen.[12] Oxygen constitutes 49.2% of the Earth's crust by mass[58] as part of oxide compounds such as silicon dioxide and is the most abundant element by mass in the Earth's crust. It is also the major component of the world's oceans (88.8% by mass).[12] Oxygen gas is the second most common component of the Earth's atmosphere, taking up 20.8% of its volume and 23.1% of its mass (some 1015 tonnes).[12][59][d] Earth is unusual among the planets of the Solar System in having such a high concentration of oxygen gas in its atmosphere: Mars (with 0.1% O
 +
2 by volume) and Venus have much less. The O
 +
2 surrounding those planets is produced solely by the action of ultraviolet radiation on oxygen-containing molecules such as carbon dioxide.
 +
 
 +
The unusually high concentration of oxygen gas on Earth is the result of the oxygen cycle. This biogeochemical cycle describes the movement of oxygen within and between its three main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth's atmosphere. Photosynthesis releases oxygen into the atmosphere, while respiration, decay, and combustion remove it from the atmosphere. In the present equilibrium, production and consumption occur at the same rate.[60]
 +
 
 +
World map showing that the sea-surface oxygen is depleted around the equator and increases towards the poles.
 +
Cold water holds more dissolved O
 +
2.
 +
Free oxygen also occurs in solution in the world's water bodies. The increased solubility of O
 +
2 at lower temperatures (see Physical properties) has important implications for ocean life, as polar oceans support a much higher density of life due to their higher oxygen content.[61] Water polluted with plant nutrients such as nitrates or phosphates may stimulate growth of algae by a process called eutrophication and the decay of these organisms and other biomaterials may reduce the O
 +
2 content in eutrophic water bodies. Scientists assess this aspect of water quality by measuring the water's biochemical oxygen demand, or the amount of O
 +
2 needed to restore it to a normal concentration.[62]
 +
 
 +
Analysis
 +
Time evolution of oxygen-18 concentration on the scale of 500 million years showing many local peaks.
 +
500 million years of climate change vs 18O
 +
Paleoclimatologists measure the ratio of oxygen-18 and oxygen-16 in the shells and skeletons of marine organisms to determine the climate millions of years ago (see oxygen isotope ratio cycle). Seawater molecules that contain the lighter isotope, oxygen-16, evaporate at a slightly faster rate than water molecules containing the 12% heavier oxygen-18, and this disparity increases at lower temperatures.[63] During periods of lower global temperatures, snow and rain from that evaporated water tends to be higher in oxygen-16, and the seawater left behind tends to be higher in oxygen-18. Marine organisms then incorporate more oxygen-18 into their skeletons and shells than they would in a warmer climate.[63] Paleoclimatologists also directly measure this ratio in the water molecules of ice core samples as old as hundreds of thousands of years.
 +
 
 +
Planetary geologists have measured the relative quantities of oxygen isotopes in samples from the Earth, the Moon, Mars, and meteorites, but were long unable to obtain reference values for the isotope ratios in the Sun, believed to be the same as those of the primordial solar nebula. Analysis of a silicon wafer exposed to the solar wind in space and returned by the crashed Genesis spacecraft has shown that the Sun has a higher proportion of oxygen-16 than does the Earth. The measurement implies that an unknown process depleted oxygen-16 from the Sun's disk of protoplanetary material prior to the coalescence of dust grains that formed the Earth.[64]
 +
 
 +
Oxygen presents two spectrophotometric absorption bands peaking at the wavelengths 687 and 760 nm. Some remote sensing scientists have proposed using the measurement of the radiance coming from vegetation canopies in those bands to characterize plant health status from a satellite platform.[65] This approach exploits the fact that in those bands it is possible to discriminate the vegetation's reflectance from its fluorescence, which is much weaker. The measurement is technically difficult owing to the low signal-to-noise ratio and the physical structure of vegetation; but it has been proposed as a possible method of monitoring the carbon cycle from satellites on a global scale.
 +
 
 +
Biological role of O2
 +
Main article: Dioxygen in biological reactions
 +
Photosynthesis and respiration
 +
A diagram of photosynthesis processes, including income of water and carbon dioxide, illumination and release of oxygen. Reactions produce ATP and NADPH in a Calvin cycle with a sugar as a by product.
 +
Photosynthesis splits water to liberate O
 +
2 and fixes CO
 +
2 into sugar in what is called a Calvin cycle.
 +
In nature, free oxygen is produced by the light-driven splitting of water during oxygenic photosynthesis. According to some estimates, green algae and cyanobacteria in marine environments provide about 70% of the free oxygen produced on Earth, and the rest is produced by terrestrial plants.[66] Other estimates of the oceanic contribution to atmospheric oxygen are higher, while some estimates are lower, suggesting oceans produce ~45% of Earth's atmospheric oxygen each year.[67]
 +
 
 +
A simplified overall formula for photosynthesis is:[68]
 +
 
 +
6 CO2 + 6 H
 +
2O + photons → C
 +
6H
 +
12O
 +
6 + 6 O
 +
2
 +
or simply
 +
 
 +
carbon dioxide + water + sunlight → glucose + dioxygen
 +
Photolytic oxygen evolution occurs in the thylakoid membranes of photosynthetic organisms and requires the energy of four photons.[e] Many steps are involved, but the result is the formation of a proton gradient across the thylakoid membrane, which is used to synthesize adenosine triphosphate (ATP) via photophosphorylation.[69] The O
 +
2 remaining (after production of the water molecule) is released into the atmosphere.[f]
 +
 
 +
Oxygen is used in mitochondria to generate ATP during oxidative phosphorylation. The reaction for aerobic respiration is essentially the reverse of photosynthesis and is simplified as:
 +
 
 +
C
 +
6H
 +
12O
 +
6 + 6 O
 +
2 → 6 CO2 + 6 H
 +
2O + 2880 kJ/mol
 +
In vertebrates, O
 +
2 diffuses through membranes in the lungs and into red blood cells. Hemoglobin binds O
 +
2, changing color from bluish red to bright red[36] (CO
 +
2 is released from another part of hemoglobin through the Bohr effect). Other animals use hemocyanin (molluscs and some arthropods) or hemerythrin (spiders and lobsters).[59] A liter of blood can dissolve 200 cm3 of O
 +
2.[59]
 +
 
 +
Until the discovery of anaerobic metazoa,[70] oxygen was thought to be a requirement for all complex life.[71]
 +
 
 +
Reactive oxygen species, such as superoxide ion (O−
 +
2) and hydrogen peroxide (H
 +
2O
 +
2), are reactive by-products of oxygen use in organisms.[59] Parts of the immune system of higher organisms create peroxide, superoxide, and singlet oxygen to destroy invading microbes. Reactive oxygen species also play an important role in the hypersensitive response of plants against pathogen attack.[69] Oxygen is damaging to obligately anaerobic organisms, which were the dominant form of early life on Earth until O
 +
2 began to accumulate in the atmosphere about 2.5 billion years ago during the Great Oxygenation Event, about a billion years after the first appearance of these organisms.[72][73]
 +
 
 +
An adult human at rest inhales 1.8 to 2.4 grams of oxygen per minute.[74] This amounts to more than 6 billion tonnes of oxygen inhaled by humanity per year.[g]
 +
 
 +
Living organisms
 +
 
 +
Partial pressures of oxygen in the human body (PO2)
 +
Unit Alveolar pulmonary
 +
gas pressures Arterial blood oxygen Venous blood gas
 +
kPa 14.2 11[75]-13[75] 4.0[75]-5.3[75]
 +
mmHg 107 75[76]-100[76] 30[77]-40[77]
 +
The free oxygen partial pressure in the body of a living vertebrate organism is highest in the respiratory system, and decreases along any arterial system, peripheral tissues, and venous system, respectively. Partial pressure is the pressure that oxygen would have if it alone occupied the volume.[78]
 +
 
 +
Build-up in the atmosphere
 +
Main article: Geological history of oxygen
 +
A graph showing time evolution of oxygen pressure on Earth; the pressure increases from zero to 0.2 atmospheres.
 +
O
 +
2 build-up in Earth's atmosphere: 1) no O
 +
2 produced; 2) O
 +
2 produced, but absorbed in oceans & seabed rock; 3) O
 +
2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4–5) O
 +
2 sinks filled and the gas accumulates
 +
Free oxygen gas was almost nonexistent in Earth's atmosphere before photosynthetic archaea and bacteria evolved, probably about 3.5 billion years ago. Free oxygen first appeared in significant quantities during the Paleoproterozoic eon (between 3.0 and 2.3 billion years ago).[79] For the first billion years, any free oxygen produced by these organisms combined with dissolved iron in the oceans to form banded iron formations. When such oxygen sinks became saturated, free oxygen began to outgas from the oceans 3–2.7 billion years ago, reaching 10% of its present level around 1.7 billion years ago.[79][80]
 +
 
 +
The presence of large amounts of dissolved and free oxygen in the oceans and atmosphere may have driven most of the extant anaerobic organisms to extinction during the Great Oxygenation Event (oxygen catastrophe) about 2.4 billion years ago. Cellular respiration using O
 +
2 enables aerobic organisms to produce much more ATP than anaerobic organisms.[81] Cellular respiration of O
 +
2 occurs in all eukaryotes, including all complex multicellular organisms such as plants and animals.
 +
 
 +
Since the beginning of the Cambrian period 540 million years ago, atmospheric O
 +
2 levels have fluctuated between 15% and 30% by volume.[82] Towards the end of the Carboniferous period (about 300 million years ago) atmospheric O
 +
2 levels reached a maximum of 35% by volume,[82] which may have contributed to the large size of insects and amphibians at this time.[83]
 +
 
 +
Variations in atmospheric oxygen concentration have shaped past climates. When oxygen declined, atmospheric density dropped, which in turn increased surface evaporation, causing precipitation increases and warmer temperatures.[84]
 +
 
 +
At the current rate of photosynthesis it would take about 2,000 years to regenerate the entire O
 +
2 in the present atmosphere.[85]
 +
 
 +
Industrial production
 +
A drawing of three vertical pipes connected at the bottom and filled with oxygen (left pipe), water (middle) and hydrogen (right). Anode and cathode electrodes are inserted into the left and right pipes and externally connected to a battery.
 +
Hofmann electrolysis apparatus used in electrolysis of water.
 +
See also: Air separation, Oxygen evolution, and Fractional distillation
 +
One hundred million tonnes of O
 +
2 are extracted from air for industrial uses annually by two primary methods.[13] The most common method is fractional distillation of liquefied air, with N
 +
2 distilling as a vapor while O
 +
2 is left as a liquid.[13]
 +
 
 +
The other primary method of producing O
 +
2 is passing a stream of clean, dry air through one bed of a pair of identical zeolite molecular sieves, which absorbs the nitrogen and delivers a gas stream that is 90% to 93% O
 +
2.[13] Simultaneously, nitrogen gas is released from the other nitrogen-saturated zeolite bed, by reducing the chamber operating pressure and diverting part of the oxygen gas from the producer bed through it, in the reverse direction of flow. After a set cycle time the operation of the two beds is interchanged, thereby allowing for a continuous supply of gaseous oxygen to be pumped through a pipeline. This is known as pressure swing adsorption. Oxygen gas is increasingly obtained by these non-cryogenic technologies (see also the related vacuum swing adsorption).[86]
 +
 
 +
Oxygen gas can also be produced through electrolysis of water into molecular oxygen and hydrogen. DC electricity must be used: if AC is used, the gases in each limb consist of hydrogen and oxygen in the explosive ratio 2:1. A similar method is the electrocatalytic O
 +
2 evolution from oxides and oxoacids. Chemical catalysts can be used as well, such as in chemical oxygen generators or oxygen candles that are used as part of the life-support equipment on submarines, and are still part of standard equipment on commercial airliners in case of depressurization emergencies. Another air separation method is forcing air to dissolve through ceramic membranes based on zirconium dioxide by either high pressure or an electric current, to produce nearly pure O
 +
2 gas.[62]
 +
 
 +
Storage
 +
 
 +
Oxygen and MAPP gas compressed gas cylinders with regulators
 +
Oxygen storage methods include high pressure oxygen tanks, cryogenics and chemical compounds. For reasons of economy, oxygen is often transported in bulk as a liquid in specially insulated tankers, since one liter of liquefied oxygen is equivalent to 840 liters of gaseous oxygen at atmospheric pressure and 20 °C (68 °F).[13] Such tankers are used to refill bulk liquid oxygen storage containers, which stand outside hospitals and other institutions that need large volumes of pure oxygen gas. Liquid oxygen is passed through heat exchangers, which convert the cryogenic liquid into gas before it enters the building. Oxygen is also stored and shipped in smaller cylinders containing the compressed gas; a form that is useful in certain portable medical applications and oxy-fuel welding and cutting.[13]
 +
 
 +
Applications
 +
See also: Breathing gas, Redox, and Combustion
 +
Medical
 +
A gray device with a label DeVILBISS LT4000 and some text on the front panel. A green plastic pipe is running from the device.
 +
An oxygen concentrator in an emphysema patient's house
 +
Main article: Oxygen therapy
 +
Uptake of O
 +
2 from the air is the essential purpose of respiration, so oxygen supplementation is used in medicine. Treatment not only increases oxygen levels in the patient's blood, but has the secondary effect of decreasing resistance to blood flow in many types of diseased lungs, easing work load on the heart. Oxygen therapy is used to treat emphysema, pneumonia, some heart disorders (congestive heart failure), some disorders that cause increased pulmonary artery pressure, and any disease that impairs the body's ability to take up and use gaseous oxygen.[87]
 +
 
 +
Treatments are flexible enough to be used in hospitals, the patient's home, or increasingly by portable devices. Oxygen tents were once commonly used in oxygen supplementation, but have since been replaced mostly by the use of oxygen masks or nasal cannulas.[88]
 +
 
 +
Hyperbaric (high-pressure) medicine uses special oxygen chambers to increase the partial pressure of O
 +
2 around the patient and, when needed, the medical staff.[89] Carbon monoxide poisoning, gas gangrene, and decompression sickness (the 'bends') are sometimes addressed with this therapy.[90] Increased O
 +
2 concentration in the lungs helps to displace carbon monoxide from the heme group of hemoglobin.[91][92] Oxygen gas is poisonous to the anaerobic bacteria that cause gas gangrene, so increasing its partial pressure helps kill them.[93][94] Decompression sickness occurs in divers who decompress too quickly after a dive, resulting in bubbles of inert gas, mostly nitrogen and helium, forming in the blood. Increasing the pressure of O
 +
2 as soon as possible helps to redissolve the bubbles back into the blood so that these excess gasses can be exhaled naturally through the lungs.[87][95][96] Normobaric oxygen administration at the highest available concentration is frequently used as first aid for any diving injury that may involve inert gas bubble formation in the tissues. There is epidemiological support for its use from a statistical study of cases recorded in a long term database.[97][98][99]
 +
 
 +
Life support and recreational use
 +
 
 +
Low pressure pure O
 +
2 is used in space suits.
 +
An application of O
 +
2 as a low-pressure breathing gas is in modern space suits, which surround their occupant's body with the breathing gas. These devices use nearly pure oxygen at about one-third normal pressure, resulting in a normal blood partial pressure of O
 +
2. This trade-off of higher oxygen concentration for lower pressure is needed to maintain suit flexibility.[100][101]
 +
 
 +
Scuba and surface-supplied underwater divers and submariners also rely on artificially delivered O
 +
2. Submarines, submersibles and atmospheric diving suits usually operate at normal atmospheric pressure. Breathing air is scrubbed of carbon dioxide by chemical extraction and oxygen is replaced to maintain a constant partial pressure. Ambient pressure divers breathe air or gas mixtures with an oxygen fraction suited to the operating depth. Pure or nearly pure O
 +
2 use in diving at pressures higher than atmospheric is usually limited to rebreathers, or decompression at relatively shallow depths (~6 meters depth, or less),[102][103] or medical treatment in recompression chambers at pressures up to 2.8 bar, where acute oxygen toxicity can be managed without the risk of drowning. Deeper diving requires significant dilution of O
 +
2 with other gases, such as nitrogen or helium, to prevent oxygen toxicity.[102]
 +
 
 +
People who climb mountains or fly in non-pressurized fixed-wing aircraft sometimes have supplemental O
 +
2 supplies.[h] Pressurized commercial airplanes have an emergency supply of O
 +
2 automatically supplied to the passengers in case of cabin depressurization. Sudden cabin pressure loss activates chemical oxygen generators above each seat, causing oxygen masks to drop. Pulling on the masks "to start the flow of oxygen" as cabin safety instructions dictate, forces iron filings into the sodium chlorate inside the canister.[62] A steady stream of oxygen gas is then produced by the exothermic reaction.
 +
 
 +
Oxygen, as a mild euphoric, has a history of recreational use in oxygen bars and in sports. Oxygen bars are establishments found in the United States since the late 1990s that offer higher than normal O
 +
2 exposure for a minimal fee.[104] Professional athletes, especially in American football, sometimes go off-field between plays to don oxygen masks to boost performance. The pharmacological effect is doubted; a placebo effect is a more likely explanation.[104] Available studies support a performance boost from oxygen enriched mixtures only if it is breathed during aerobic exercise.[105]
 +
 
 +
Other recreational uses that do not involve breathing include pyrotechnic applications, such as George Goble's five-second ignition of barbecue grills.[106]
 +
 
 +
Industrial
 +
An elderly worker in a helmet is facing his side to the viewer in an industrial hall. The hall is dark but is illuminated yellow glowing splashes of a melted substance.
 +
Most commercially produced O
 +
2 is used to smelt and/or decarburize iron.
 +
Smelting of iron ore into steel consumes 55% of commercially produced oxygen.[62] In this process, O
 +
2 is injected through a high-pressure lance into molten iron, which removes sulfur impurities and excess carbon as the respective oxides, SO
 +
2 and CO
 +
2. The reactions are exothermic, so the temperature increases to 1,700 °C.[62]
 +
 
 +
Another 25% of commercially produced oxygen is used by the chemical industry.[62] Ethylene is reacted with O
 +
2 to create ethylene oxide, which, in turn, is converted into ethylene glycol; the primary feeder material used to manufacture a host of products, including antifreeze and polyester polymers (the precursors of many plastics and fabrics).[62]
 +
 
 +
Most of the remaining 20% of commercially produced oxygen is used in medical applications, metal cutting and welding, as an oxidizer in rocket fuel, and in water treatment.[62] Oxygen is used in oxyacetylene welding burning acetylene with O
 +
2 to produce a very hot flame. In this process, metal up to 60 cm (24 in) thick is first heated with a small oxy-acetylene flame and then quickly cut by a large stream of O
 +
2.[107]
 +
 
 +
Compounds
 +
Main article: Compounds of oxygen
 +
Water flowing from a bottle into a glass.
 +
Water (H
 +
2O) is the most familiar oxygen compound.
 +
The oxidation state of oxygen is −2 in almost all known compounds of oxygen. The oxidation state −1 is found in a few compounds such as peroxides.[108] Compounds containing oxygen in other oxidation states are very uncommon: −1/2 (superoxides), −1/3 (ozonides), 0 (elemental, hypofluorous acid), +1/2 (dioxygenyl), +1 (dioxygen difluoride), and +2 (oxygen difluoride).[109]
 +
 
 +
Oxides and other inorganic compounds
 +
Water (H
 +
2O) is an oxide of hydrogen and the most familiar oxygen compound. Hydrogen atoms are covalently bonded to oxygen in a water molecule but also have an additional attraction (about 23.3 kJ/mol per hydrogen atom) to an adjacent oxygen atom in a separate molecule.[110] These hydrogen bonds between water molecules hold them approximately 15% closer than what would be expected in a simple liquid with just van der Waals forces.[111][i]
 +
 
 +
A rusty piece of a bolt.
 +
Oxides, such as iron oxide or rust, form when oxygen combines with other elements.
 +
Due to its electronegativity, oxygen forms chemical bonds with almost all other elements to give corresponding oxides. The surface of most metals, such as aluminium and titanium, are oxidized in the presence of air and become coated with a thin film of oxide that passivates the metal and slows further corrosion. Many oxides of the transition metals are non-stoichiometric compounds, with slightly less metal than the chemical formula would show. For example, the mineral FeO (wüstite) is written as Fe
 +
1 − xO, where x is usually around 0.05.[112]
 +
 
 +
Oxygen is present in the atmosphere in trace quantities in the form of carbon dioxide (CO
 +
2). The Earth's crustal rock is composed in large part of oxides of silicon (silica SiO
 +
2, as found in granite and quartz), aluminium (aluminium oxide Al
 +
2O
 +
3, in bauxite and corundum), iron (iron(III) oxide Fe
 +
2O
 +
3, in hematite and rust), and calcium carbonate (in limestone). The rest of the Earth's crust is also made of oxygen compounds, in particular various complex silicates (in silicate minerals). The Earth's mantle, of much larger mass than the crust, is largely composed of silicates of magnesium and iron.
 +
 
 +
Water-soluble silicates in the form of Na
 +
4SiO
 +
4, Na
 +
2SiO
 +
3, and Na
 +
2Si
 +
2O
 +
5 are used as detergents and adhesives.[113]
 +
 
 +
Oxygen also acts as a ligand for transition metals, forming transition metal dioxygen complexes, which feature metal–O
 +
2. This class of compounds includes the heme proteins hemoglobin and myoglobin.[114] An exotic and unusual reaction occurs with PtF
 +
6, which oxidizes oxygen to give O2+PtF6−, dioxygenyl hexafluoroplatinate.[115]
 +
 
 +
Organic compounds
 +
A ball structure of a molecule. Its backbone is a zig-zag chain of three carbon atoms connected in the center to an oxygen atom and on the end to 6 hydrogens.
 +
Acetone is an important feeder material in the chemical industry.
 +
  Oxygen
 +
  Carbon
 +
  Hydrogen
 +
Among the most important classes of organic compounds that contain oxygen are (where "R" is an organic group): alcohols (R-OH); ethers (R-O-R); ketones (R-CO-R); aldehydes (R-CO-H); carboxylic acids (R-COOH); esters (R-COO-R); acid anhydrides (R-CO-O-CO-R); and amides (R-C(O)-NR
 +
2). There are many important organic solvents that contain oxygen, including: acetone, methanol, ethanol, isopropanol, furan, THF, diethyl ether, dioxane, ethyl acetate, DMF, DMSO, acetic acid, and formic acid. Acetone ((CH
 +
3)
 +
2CO) and phenol (C
 +
6H
 +
5OH) are used as feeder materials in the synthesis of many different substances. Other important organic compounds that contain oxygen are: glycerol, formaldehyde, glutaraldehyde, citric acid, acetic anhydride, and acetamide. Epoxides are ethers in which the oxygen atom is part of a ring of three atoms. The element is similarly found in almost all biomolecules that are important to (or generated by) life.
 +
 
 +
Oxygen reacts spontaneously with many organic compounds at or below room temperature in a process called autoxidation.[116] Most of the organic compounds that contain oxygen are not made by direct action of O
 +
2. Organic compounds important in industry and commerce that are made by direct oxidation of a precursor include ethylene oxide and peracetic acid.[113]
 +
 
 +
Safety and precautions
 +
The NFPA 704 standard rates compressed oxygen gas as nonhazardous to health, nonflammable and nonreactive, but an oxidizer. Refrigerated liquid oxygen (LOX) is given a health hazard rating of 3 (for increased risk of hyperoxia from condensed vapors, and for hazards common to cryogenic liquids such as frostbite), and all other ratings are the same as the compressed gas form.[117]
 +
 
 +
Toxicity
 +
Main article: Oxygen toxicity
 +
A diagraph showing a man torso and listing symptoms of oxygen toxicity: Eyes – visual field loss, near)sightedness, cataract formation, bleeding, fibrosis; Head – seizures; Muscles – twitching; Respiratory system – jerky breathing, irritation, coughing, pain, shortness of breath, tracheobronchitis, acute respiratory distress syndrome.
 +
Main symptoms of oxygen toxicity[118]
 +
Oxygen gas (O
 +
2) can be toxic at elevated partial pressures, leading to convulsions and other health problems.[102][j][119] Oxygen toxicity usually begins to occur at partial pressures more than 50 kilopascals (kPa), equal to about 50% oxygen composition at standard pressure or 2.5 times the normal sea-level O
 +
2 partial pressure of about 21 kPa. This is not a problem except for patients on mechanical ventilators, since gas supplied through oxygen masks in medical applications is typically composed of only 30%–50% O
 +
2 by volume (about 30 kPa at standard pressure).[6]
 +
 
 +
At one time, premature babies were placed in incubators containing O
 +
2-rich air, but this practice was discontinued after some babies were blinded by the oxygen content being too high.[6]
 +
 
 +
Breathing pure O
 +
2 in space applications, such as in some modern space suits, or in early spacecraft such as Apollo, causes no damage due to the low total pressures used.[100][120] In the case of spacesuits, the O
 +
2 partial pressure in the breathing gas is, in general, about 30 kPa (1.4 times normal), and the resulting O
 +
2 partial pressure in the astronaut's arterial blood is only marginally more than normal sea-level O
 +
2 partial pressure.[121]
 +
 
 +
Oxygen toxicity to the lungs and central nervous system can also occur in deep scuba diving and surface supplied diving.[6][102] Prolonged breathing of an air mixture with an O
 +
2 partial pressure more than 60 kPa can eventually lead to permanent pulmonary fibrosis.[122] Exposure to a O
 +
2 partial pressures greater than 160 kPa (about 1.6 atm) may lead to convulsions (normally fatal for divers). Acute oxygen toxicity (causing seizures, its most feared effect for divers) can occur by breathing an air mixture with 21% O
 +
2 at 66 m (217 ft) or more of depth; the same thing can occur by breathing 100% O
 +
2 at only 6 m (20 ft).[122][123][124][125]
 +
 
 +
Combustion and other hazards
 +
The inside of a small spaceship, charred and apparently destroyed.
 +
The interior of the Apollo 1 Command Module. Pure O
 +
2 at higher than normal pressure and a spark led to a fire and the loss of the Apollo 1 crew.
 +
Highly concentrated sources of oxygen promote rapid combustion. Fire and explosion hazards exist when concentrated oxidants and fuels are brought into close proximity; an ignition event, such as heat or a spark, is needed to trigger combustion.[28][126] Oxygen is the oxidant, not the fuel, but nevertheless the source of most of the chemical energy released in combustion.[28][35]
 +
 
 +
Concentrated O
 +
2 will allow combustion to proceed rapidly and energetically.[126] Steel pipes and storage vessels used to store and transmit both gaseous and liquid oxygen will act as a fuel; and therefore the design and manufacture of O
 +
2 systems requires special training to ensure that ignition sources are minimized.[126] The fire that killed the Apollo 1 crew in a launch pad test spread so rapidly because the capsule was pressurized with pure O
 +
2 but at slightly more than atmospheric pressure, instead of the ​1⁄3 normal pressure that would be used in a mission.[k][128]
 +
 
 +
Liquid oxygen spills, if allowed to soak into organic matter, such as wood, petrochemicals, and asphalt can cause these materials to detonate unpredictably on subsequent mechanical impact.[126]
 +
 
 +
See also
 +
Geological history of oxygen
 +
Hypoxia (environmental) for O
 +
2 depletion in aquatic ecology
 +
Ocean deoxygenation
 +
Hypoxia (medical), a lack of oxygen
 +
Limiting oxygen concentration
 +
Oxygen compounds
 +
Oxygen plant
 +
Oxygen sensor
 +
Books
 +
View or order collections of articles
 +
OxygenPeriod 2 elementsChalcogensChemical elements (sorted alphabetically)Chemical elements (sorted by number)
 +
Portals
 +
Access related topics
 +
Papapishu-Lab-icon-6.svgChemistry portalWHO Rod.svgMedicine portal
 +
Find out more on Wikipedia's
 +
Sister projects
 +
Media
 +
from CommonsDefinitions
 +
from WiktionaryTextbooks
 +
from WikibooksLearning resources
 +
from Wikiversity
 +
Notes
 +
These results were mostly ignored until 1860. Part of this rejection was due to the belief that atoms of one element would have no chemical affinity towards atoms of the same element, and part was due to apparent exceptions to Avogadro's law that were not explained until later in terms of dissociating molecules.
 +
An orbital is a concept from quantum mechanics that models an electron as a wave-like particle that has a spatial distribution about an atom or molecule.
 +
Oxygen's paramagnetism can be used analytically in paramagnetic oxygen gas analysers that determine the purity of gaseous oxygen. ("Company literature of Oxygen analyzers (triplet)". Servomex. Archived from the original on March 8, 2008. Retrieved December 15, 2007.)
 +
Figures given are for values up to 50 miles (80 km) above the surface
 +
Thylakoid membranes are part of chloroplasts in algae and plants while they simply are one of many membrane structures in cyanobacteria. In fact, chloroplasts are thought to have evolved from cyanobacteria that were once symbiotic partners with the progenitors of plants and algae.
 +
Water oxidation is catalyzed by a manganese-containing enzyme complex known as the oxygen evolving complex (OEC) or water-splitting complex found associated with the lumenal side of thylakoid membranes. Manganese is an important cofactor, and calcium and chloride are also required for the reaction to occur. (Raven 2005)
 +
(1.8 grams/min/person)×(60 min/h)×(24 h/day)×(365 days/year)×(6.6 billion people)/1,000,000 g/t=6.24 billion tonnes
 +
The reason is that increasing the proportion of oxygen in the breathing gas at low pressure acts to augment the inspired O
 +
2 partial pressure nearer to that found at sea-level.
 +
Also, since oxygen has a higher electronegativity than hydrogen, the charge difference makes it a polar molecule. The interactions between the different dipoles of each molecule cause a net attraction force.
 +
Since O
 +
2's partial pressure is the fraction of O
 +
2 times the total pressure, elevated partial pressures can occur either from high O
 +
2 fraction in breathing gas or from high breathing gas pressure, or a combination of both.
 +
No single ignition source of the fire was conclusively identified, although some evidence points to an arc from an electrical spark.[127]
 +
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5
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6
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Lu
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Hf
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Re
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7
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U
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Pu
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Es
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No
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Lr
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Rf
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Db
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Sg
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Bh
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Hs
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Mt
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Ds
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Rg
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Cn
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Nh
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Fl
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Mc
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Lv
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Ts
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Og
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Alkali metal Alkaline earth metal Lan­thanide Actinide Transition metal Post-​transition metal Metalloid Reactive nonmetal Noble gas Unknown
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Energy
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From Wikipedia, the free encyclopedia
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Jump to navigationJump to search
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This article is about the scalar physical quantity. For an overview of and topical guide to energy, see Outline of energy. For other uses, see Energy (disambiguation).
 +
"Energetic" redirects here. For other uses, see Energetic (disambiguation).
 +
Energy
 +
Sun in February (black version).jpg
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The Sun is the source of energy for most of life on Earth. As a star, the Sun is heated to high temperatures by the conversion of nuclear binding energy due to the fusion of hydrogen in its core. This energy is ultimately transferred (released) into space mainly in the form of radiant (light) energy.
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Common symbols
 +
E
 +
SI unit joule
 +
Other units
 +
erg, calorie, kcal, BTU, kW⋅h, eV
 +
In SI base units J = kg m2 s−2
 +
Extensive? yes
 +
Conserved? yes
 +
Dimension M L2 T−2
 +
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.[note 1] Energy is a conserved quantity; the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton.
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Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object's temperature.
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Mass and energy are closely related. Due to mass–energy equivalence, any object that has mass when stationary (called rest mass) also has an equivalent amount of energy whose form is called rest energy, and any additional energy (of any form) acquired by the object above that rest energy will increase the object's total mass just as it increases its total energy. For example, after heating an object, its increase in energy could be measured as a small increase in mass, with a sensitive enough scale.
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Living organisms require available energy to stay alive, such as the energy humans get from food. Human civilization requires energy to function, which it gets from energy resources such as fossil fuels, nuclear fuel, or renewable energy. The processes of Earth's climate and ecosystem are driven by the radiant energy Earth receives from the sun and the geothermal energy contained within the earth.
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Contents
 +
1 Forms
 +
2 History
 +
3 Units of measure
 +
4 Scientific use
 +
4.1 Classical mechanics
 +
4.2 Chemistry
 +
4.3 Biology
 +
4.4 Earth sciences
 +
4.5 Cosmology
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4.6 Quantum mechanics
 +
4.7 Relativity
 +
5 Transformation
 +
5.1 Conservation of energy and mass in transformation
 +
5.2 Reversible and non-reversible transformations
 +
6 Conservation of energy
 +
7 Energy transfer
 +
7.1 Closed systems
 +
7.2 Open systems
 +
8 Thermodynamics
 +
8.1 Internal energy
 +
8.2 First law of thermodynamics
 +
8.3 Equipartition of energy
 +
9 See also
 +
10 Notes
 +
11 References
 +
12 Further reading
 +
12.1 Journals
 +
13 External links
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Forms
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 +
This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.
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Find sources: "Energy" – news · newspapers · books · scholar · JSTOR (September 2016) (Learn how and when to remove this template message)
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In a typical lightning strike, 500 megajoules of electric potential energy is converted into the same amount of energy in other forms, mostly light energy, sound energy and thermal energy.
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Thermal energy is energy of microscopic constituents of matter, which may include both kinetic and potential energy.
 +
The total energy of a system can be subdivided and classified into potential energy, kinetic energy, or combinations of the two in various ways. Kinetic energy is determined by the movement of an object – or the composite motion of the components of an object – and potential energy reflects the potential of an object to have motion, and generally is a function of the position of an object within a field or may be stored in the field itself.
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While these two categories are sufficient to describe all forms of energy, it is often convenient to refer to particular combinations of potential and kinetic energy as its own form. For example, macroscopic mechanical energy is the sum of translational and rotational kinetic and potential energy in a system neglects the kinetic energy due to temperature, and nuclear energy which combines utilize potentials from the nuclear force and the weak force), among others.[citation needed]
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 +
 
 +
Some forms of energy (that an object or system can have as a measurable property)
 +
Type of energy Description
 +
Mechanical the sum of macroscopic translational and rotational kinetic and potential energies
 +
Electric potential energy due to or stored in electric fields
 +
Magnetic potential energy due to or stored in magnetic fields
 +
Gravitational potential energy due to or stored in gravitational fields
 +
Chemical potential energy due to chemical bonds
 +
Ionization potential energy that binds an electron to its atom or molecule
 +
Nuclear potential energy that binds nucleons to form the atomic nucleus (and nuclear reactions)
 +
Chromodynamic potential energy that binds quarks to form hadrons
 +
Elastic potential energy due to the deformation of a material (or its container) exhibiting a restorative force
 +
Mechanical wave kinetic and potential energy in an elastic material due to a propagated deformational wave
 +
Sound wave kinetic and potential energy in a fluid due to a sound propagated wave (a particular form of mechanical wave)
 +
Radiant potential energy stored in the fields of propagated by electromagnetic radiation, including light
 +
Rest potential energy due to an object's rest mass
 +
Thermal kinetic energy of the microscopic motion of particles, a form of disordered equivalent of mechanical energy
 +
History
 +
Main articles: History of energy and timeline of thermodynamics, statistical mechanics, and random processes
 +
 
 +
Thomas Young – the first to use the term "energy" in the modern sense.
 +
The word energy derives from the Ancient Greek: ἐνέργεια, translit. energeia, lit. 'activity, operation',[1] which possibly appears for the first time in the work of Aristotle in the 4th century BC. In contrast to the modern definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness and pleasure.
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In the late 17th century, Gottfried Leibniz proposed the idea of the Latin: vis viva, or living force, which defined as the product of the mass of an object and its velocity squared; he believed that total vis viva was conserved. To account for slowing due to friction, Leibniz theorized that thermal energy consisted of the random motion of the constituent parts of matter, although it would be more than a century until this was generally accepted. The modern analog of this property, kinetic energy, differs from vis viva only by a factor of two.
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 +
In 1807, Thomas Young was possibly the first to use the term "energy" instead of vis viva, in its modern sense.[2] Gustave-Gaspard Coriolis described "kinetic energy" in 1829 in its modern sense, and in 1853, William Rankine coined the term "potential energy". The law of conservation of energy was also first postulated in the early 19th century, and applies to any isolated system. It was argued for some years whether heat was a physical substance, dubbed the caloric, or merely a physical quantity, such as momentum. In 1845 James Prescott Joule discovered the link between mechanical work and the generation of heat.
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 +
These developments led to the theory of conservation of energy, formalized largely by William Thomson (Lord Kelvin) as the field of thermodynamics. Thermodynamics aided the rapid development of explanations of chemical processes by Rudolf Clausius, Josiah Willard Gibbs, and Walther Nernst. It also led to a mathematical formulation of the concept of entropy by Clausius and to the introduction of laws of radiant energy by Jožef Stefan. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.[3] Thus, since 1918, theorists have understood that the law of conservation of energy is the direct mathematical consequence of the translational symmetry of the quantity conjugate to energy, namely time.
 +
 
 +
Units of measure
 +
 
 +
Joule's apparatus for measuring the mechanical equivalent of heat. A descending weight attached to a string causes a paddle immersed in water to rotate.
 +
Main article: Units of energy
 +
In 1843, James Prescott Joule independently discovered the mechanical equivalent in a series of experiments. The most famous of them used the "Joule apparatus": a descending weight, attached to a string, caused rotation of a paddle immersed in water, practically insulated from heat transfer. It showed that the gravitational potential energy lost by the weight in descending was equal to the internal energy gained by the water through friction with the paddle.
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 +
In the International System of Units (SI), the unit of energy is the joule, named after James Prescott Joule. It is a derived unit. It is equal to the energy expended (or work done) in applying a force of one newton through a distance of one metre. However energy is also expressed in many other units not part of the SI, such as ergs, calories, British Thermal Units, kilowatt-hours and kilocalories, which require a conversion factor when expressed in SI units.
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 +
The SI unit of energy rate (energy per unit time) is the watt, which is a joule per second. Thus, one joule is one watt-second, and 3600 joules equal one watt-hour. The CGS energy unit is the erg and the imperial and US customary unit is the foot pound. Other energy units such as the electronvolt, food calorie or thermodynamic kcal (based on the temperature change of water in a heating process), and BTU are used in specific areas of science and commerce.
 +
 
 +
Scientific use
 +
Classical mechanics
 +
Part of a series of articles about
 +
Classical mechanics
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{{\vec {F}}=m{\vec {a}}} {\vec {F}}=m{\vec {a}}
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Second law of motion
 +
History Timeline
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Branches[show]
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Fundamentals[show]
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Formulations[show]
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Core topics[show]
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Rotation[show]
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Scientists[show]
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vte
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Main articles: Mechanics, Mechanical work, and Thermodynamics
 +
In classical mechanics, energy is a conceptually and mathematically useful property, as it is a conserved quantity. Several formulations of mechanics have been developed using energy as a core concept.
 +
 
 +
Work, a function of energy, is force times distance.
 +
 
 +
{W=\int _{C}\mathbf {F} \cdot \mathrm {d} \mathbf {s} } W=\int _{C}\mathbf {F} \cdot \mathrm {d} \mathbf {s}
 +
This says that the work ( {W} W) is equal to the line integral of the force F along a path C; for details see the mechanical work article. Work and thus energy is frame dependent. For example, consider a ball being hit by a bat. In the center-of-mass reference frame, the bat does no work on the ball. But, in the reference frame of the person swinging the bat, considerable work is done on the ball.
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 +
The total energy of a system is sometimes called the Hamiltonian, after William Rowan Hamilton. The classical equations of motion can be written in terms of the Hamiltonian, even for highly complex or abstract systems. These classical equations have remarkably direct analogs in nonrelativistic quantum mechanics.[4]
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 +
Another energy-related concept is called the Lagrangian, after Joseph-Louis Lagrange. This formalism is as fundamental as the Hamiltonian, and both can be used to derive the equations of motion or be derived from them. It was invented in the context of classical mechanics, but is generally useful in modern physics. The Lagrangian is defined as the kinetic energy minus the potential energy. Usually, the Lagrange formalism is mathematically more convenient than the Hamiltonian for non-conservative systems (such as systems with friction).
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 +
Noether's theorem (1918) states that any differentiable symmetry of the action of a physical system has a corresponding conservation law. Noether's theorem has become a fundamental tool of modern theoretical physics and the calculus of variations. A generalisation of the seminal formulations on constants of motion in Lagrangian and Hamiltonian mechanics (1788 and 1833, respectively), it does not apply to systems that cannot be modeled with a Lagrangian; for example, dissipative systems with continuous symmetries need not have a corresponding conservation law.
 +
 
 +
Chemistry
 +
In the context of chemistry, energy is an attribute of a substance as a consequence of its atomic, molecular or aggregate structure. Since a chemical transformation is accompanied by a change in one or more of these kinds of structure, it is invariably accompanied by an increase or decrease of energy of the substances involved. Some energy is transferred between the surroundings and the reactants of the reaction in the form of heat or light; thus the products of a reaction may have more or less energy than the reactants. A reaction is said to be exergonic if the final state is lower on the energy scale than the initial state; in the case of endergonic reactions the situation is the reverse. Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy. The speed of a chemical reaction (at given temperature T) is related to the activation energy E, by the Boltzmann's population factor e−E/kT – that is the probability of molecule to have energy greater than or equal to E at the given temperature T. This exponential dependence of a reaction rate on temperature is known as the Arrhenius equation.The activation energy necessary for a chemical reaction can be in the form of thermal energy.
 +
 
 +
Biology
 +
Main articles: Bioenergetics and Food energy
 +
 
 +
Basic overview of energy and human life.
 +
In biology, energy is an attribute of all biological systems from the biosphere to the smallest living organism. Within an organism it is responsible for growth and development of a biological cell or an organelle of a biological organism. Energy is thus often said to be stored by cells in the structures of molecules of substances such as carbohydrates (including sugars), lipids, and proteins, which release energy when reacted with oxygen in respiration. In human terms, the human equivalent (H-e) (Human energy conversion) indicates, for a given amount of energy expenditure, the relative quantity of energy needed for human metabolism, assuming an average human energy expenditure of 12,500 kJ per day and a basal metabolic rate of 80 watts. For example, if our bodies run (on average) at 80 watts, then a light bulb running at 100 watts is running at 1.25 human equivalents (100 ÷ 80) i.e. 1.25 H-e. For a difficult task of only a few seconds' duration, a person can put out thousands of watts, many times the 746 watts in one official horsepower. For tasks lasting a few minutes, a fit human can generate perhaps 1,000 watts. For an activity that must be sustained for an hour, output drops to around 300; for an activity kept up all day, 150 watts is about the maximum.[5] The human equivalent assists understanding of energy flows in physical and biological systems by expressing energy units in human terms: it provides a "feel" for the use of a given amount of energy.[6]
 +
 
 +
Sunlight's radiant energy is also captured by plants as chemical potential energy in photosynthesis, when carbon dioxide and water (two low-energy compounds) are converted into the high-energy compounds carbohydrates, lipids, and proteins. Plants also release oxygen during photosynthesis, which is utilized by living organisms as an electron acceptor, to release the energy of carbohydrates, lipids, and proteins. Release of the energy stored during photosynthesis as heat or light may be triggered suddenly by a spark, in a forest fire, or it may be made available more slowly for animal or human metabolism, when these molecules are ingested, and catabolism is triggered by enzyme action.
 +
 
 +
Any living organism relies on an external source of energy – radiant energy from the Sun in the case of green plants, chemical energy in some form in the case of animals – to be able to grow and reproduce. The daily 1500–2000 Calories (6–8 MJ) recommended for a human adult are taken as a combination of oxygen and food molecules, the latter mostly carbohydrates and fats, of which glucose (C6H12O6) and stearin (C57H110O6) are convenient examples. The food molecules are oxidised to carbon dioxide and water in the mitochondria
 +
 
 +
{{\ce {C6H12O6 + 6O2 -> 6CO2 + 6H2O}}} {{\ce {C6H12O6 + 6O2 -> 6CO2 + 6H2O}}}
 +
C57H110O6 + 81.5O2 → 57CO2 + 55H2O
 +
and some of the energy is used to convert ADP into ATP.
 +
 
 +
ADP + HPO42− → ATP + H2O
 +
The rest of the chemical energy in O2[7] and the carbohydrate or fat is converted into heat: the ATP is used as a sort of "energy currency", and some of the chemical energy it contains is used for other metabolism when ATP reacts with OH groups and eventually splits into ADP and phosphate (at each stage of a metabolic pathway, some chemical energy is converted into heat). Only a tiny fraction of the original chemical energy is used for work:[note 2]
 +
 
 +
gain in kinetic energy of a sprinter during a 100 m race: 4 kJ
 +
gain in gravitational potential energy of a 150 kg weight lifted through 2 metres: 3 kJ
 +
Daily food intake of a normal adult: 6–8 MJ
 +
It would appear that living organisms are remarkably inefficient (in the physical sense) in their use of the energy they receive (chemical or radiant energy), and it is true that most real machines manage higher efficiencies. In growing organisms the energy that is converted to heat serves a vital purpose, as it allows the organism tissue to be highly ordered with regard to the molecules it is built from. The second law of thermodynamics states that energy (and matter) tends to become more evenly spread out across the universe: to concentrate energy (or matter) in one specific place, it is necessary to spread out a greater amount of energy (as heat) across the remainder of the universe ("the surroundings").[note 3] Simpler organisms can achieve higher energy efficiencies than more complex ones, but the complex organisms can occupy ecological niches that are not available to their simpler brethren. The conversion of a portion of the chemical energy to heat at each step in a metabolic pathway is the physical reason behind the pyramid of biomass observed in ecology: to take just the first step in the food chain, of the estimated 124.7 Pg/a of carbon that is fixed by photosynthesis, 64.3 Pg/a (52%) are used for the metabolism of green plants,[8] i.e. reconverted into carbon dioxide and heat.
 +
 
 +
Earth sciences
 +
In geology, continental drift, mountain ranges, volcanoes, and earthquakes are phenomena that can be explained in terms of energy transformations in the Earth's interior,[9] while meteorological phenomena like wind, rain, hail, snow, lightning, tornadoes and hurricanes are all a result of energy transformations brought about by solar energy on the atmosphere of the planet Earth.
 +
 
 +
Sunlight may be stored as gravitational potential energy after it strikes the Earth, as (for example) water evaporates from oceans and is deposited upon mountains (where, after being released at a hydroelectric dam, it can be used to drive turbines or generators to produce electricity). Sunlight also drives many weather phenomena, save those generated by volcanic events. An example of a solar-mediated weather event is a hurricane, which occurs when large unstable areas of warm ocean, heated over months, give up some of their thermal energy suddenly to power a few days of violent air movement.
 +
 
 +
In a slower process, radioactive decay of atoms in the core of the Earth releases heat. This thermal energy drives plate tectonics and may lift mountains, via orogenesis. This slow lifting represents a kind of gravitational potential energy storage of the thermal energy, which may be later released to active kinetic energy in landslides, after a triggering event. Earthquakes also release stored elastic potential energy in rocks, a store that has been produced ultimately from the same radioactive heat sources. Thus, according to present understanding, familiar events such as landslides and earthquakes release energy that has been stored as potential energy in the Earth's gravitational field or elastic strain (mechanical potential energy) in rocks. Prior to this, they represent release of energy that has been stored in heavy atoms since the collapse of long-destroyed supernova stars created these atoms.
 +
 
 +
Cosmology
 +
In cosmology and astronomy the phenomena of stars, nova, supernova, quasars and gamma-ray bursts are the universe's highest-output energy transformations of matter. All stellar phenomena (including solar activity) are driven by various kinds of energy transformations. Energy in such transformations is either from gravitational collapse of matter (usually molecular hydrogen) into various classes of astronomical objects (stars, black holes, etc.), or from nuclear fusion (of lighter elements, primarily hydrogen). The nuclear fusion of hydrogen in the Sun also releases another store of potential energy which was created at the time of the Big Bang. At that time, according to theory, space expanded and the universe cooled too rapidly for hydrogen to completely fuse into heavier elements. This meant that hydrogen represents a store of potential energy that can be released by fusion. Such a fusion process is triggered by heat and pressure generated from gravitational collapse of hydrogen clouds when they produce stars, and some of the fusion energy is then transformed into sunlight.
 +
 
 +
 
 +
Quantum mechanics
 +
Main article: Energy operator
 +
In quantum mechanics, energy is defined in terms of the energy operator as a time derivative of the wave function. The Schrödinger equation equates the energy operator to the full energy of a particle or a system. Its results can be considered as a definition of measurement of energy in quantum mechanics. The Schrödinger equation describes the space- and time-dependence of a slowly changing (non-relativistic) wave function of quantum systems. The solution of this equation for a bound system is discrete (a set of permitted states, each characterized by an energy level) which results in the concept of quanta. In the solution of the Schrödinger equation for any oscillator (vibrator) and for electromagnetic waves in a vacuum, the resulting energy states are related to the frequency by Planck's relation: {E=h\nu } E=h\nu (where {h} h is Planck's constant and {\nu } \nu  the frequency). In the case of an electromagnetic wave these energy states are called quanta of light or photons.
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Relativity
 +
When calculating kinetic energy (work to accelerate a massive body from zero speed to some finite speed) relativistically – using Lorentz transformations instead of Newtonian mechanics – Einstein discovered an unexpected by-product of these calculations to be an energy term which does not vanish at zero speed. He called it rest energy: energy which every massive body must possess even when being at rest. The amount of energy is directly proportional to the mass of the body:
 +
 
 +
{E_{0}=mc^{2}} {E_{0}=mc^{2}},
 +
where
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 +
m is the mass of the body,
 +
c is the speed of light in vacuum,
 +
{E_{0}} E_{0} is the rest energy.
 +
For example, consider electron–positron annihilation, in which the rest energy of these two individual particles (equivalent to their rest mass) is converted to the radiant energy of the photons produced in the process. In this system the matter and antimatter (electrons and positrons) are destroyed and changed to non-matter (the photons). However, the total mass and total energy do not change during this interaction. The photons each have no rest mass but nonetheless have radiant energy which exhibits the same inertia as did the two original particles. This is a reversible process – the inverse process is called pair creation – in which the rest mass of particles is created from the radiant energy of two (or more) annihilating photons.
 +
 
 +
In general relativity, the stress–energy tensor serves as the source term for the gravitational field, in rough analogy to the way mass serves as the source term in the non-relativistic Newtonian approximation.[10]
 +
 
 +
Energy and mass are manifestations of one and the same underlying physical property of a system. This property is responsible for the inertia and strength of gravitational interaction of the system ("mass manifestations"), and is also responsible for the potential ability of the system to perform work or heating ("energy manifestations"), subject to the limitations of other physical laws.
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In classical physics, energy is a scalar quantity, the canonical conjugate to time. In special relativity energy is also a scalar (although not a Lorentz scalar but a time component of the energy–momentum 4-vector).[10] In other words, energy is invariant with respect to rotations of space, but not invariant with respect to rotations of space-time (= boosts).
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Transformation
 +
Main article: Energy transformation
 +
 
 +
Some forms of transfer of energy ("energy in transit") from one object or system to another
 +
Type of transfer process Description
 +
Heat that amount of thermal energy in transit spontaneously towards a lower-temperature object
 +
Work that amount of energy in transit due to a displacement in the direction of an applied force
 +
Transfer of material that amount of energy carried by matter that is moving from one system to another
 +
 
 +
A turbo generator transforms the energy of pressurised steam into electrical energy
 +
Energy may be transformed between different forms at various efficiencies. Items that transform between these forms are called transducers. Examples of transducers include a battery, from chemical energy to electric energy; a dam: gravitational potential energy to kinetic energy of moving water (and the blades of a turbine) and ultimately to electric energy through an electric generator; or a heat engine, from heat to work.
 +
 
 +
Examples of energy transformation include generating electric energy from heat energy via a steam turbine, or lifting an object against gravity using electrical energy driving a crane motor. Lifting against gravity performs mechanical work on the object and stores gravitational potential energy in the object. If the object falls to the ground, gravity does mechanical work on the object which transforms the potential energy in the gravitational field to the kinetic energy released as heat on impact with the ground. Our Sun transforms nuclear potential energy to other forms of energy; its total mass does not decrease due to that in itself (since it still contains the same total energy even if in different forms), but its mass does decrease when the energy escapes out to its surroundings, largely as radiant energy.
 +
 
 +
There are strict limits to how efficiently heat can be converted into work in a cyclic process, e.g. in a heat engine, as described by Carnot's theorem and the second law of thermodynamics. However, some energy transformations can be quite efficient. The direction of transformations in energy (what kind of energy is transformed to what other kind) is often determined by entropy (equal energy spread among all available degrees of freedom) considerations. In practice all energy transformations are permitted on a small scale, but certain larger transformations are not permitted because it is statistically unlikely that energy or matter will randomly move into more concentrated forms or smaller spaces.
 +
 
 +
Energy transformations in the universe over time are characterized by various kinds of potential energy that has been available since the Big Bang later being "released" (transformed to more active types of energy such as kinetic or radiant energy) when a triggering mechanism is available. Familiar examples of such processes include nuclear decay, in which energy is released that was originally "stored" in heavy isotopes (such as uranium and thorium), by nucleosynthesis, a process ultimately using the gravitational potential energy released from the gravitational collapse of supernovae, to store energy in the creation of these heavy elements before they were incorporated into the solar system and the Earth. This energy is triggered and released in nuclear fission bombs or in civil nuclear power generation. Similarly, in the case of a chemical explosion, chemical potential energy is transformed to kinetic energy and thermal energy in a very short time. Yet another example is that of a pendulum. At its highest points the kinetic energy is zero and the gravitational potential energy is at maximum. At its lowest point the kinetic energy is at maximum and is equal to the decrease of potential energy. If one (unrealistically) assumes that there is no friction or other losses, the conversion of energy between these processes would be perfect, and the pendulum would continue swinging forever.
 +
 
 +
Energy is also transferred from potential energy ( {E_{p}} E_{p}) to kinetic energy ( {E_{k}} E_{k}) and then back to potential energy constantly. This is referred to as conservation of energy. In this closed system, energy cannot be created or destroyed; therefore, the initial energy and the final energy will be equal to each other. This can be demonstrated by the following:
 +
 
 +
{E_{pi}+E_{ki}=E_{pF}+E_{kF}} E_{pi}+E_{ki}=E_{pF}+E_{kF}
 +
 
 +
 +
 
 +
 +
 
 +
 +
 
 +
 +
 
 +
(4)
 +
 
 +
The equation can then be simplified further since {E_{p}=mgh} E_{p}=mgh (mass times acceleration due to gravity times the height) and {E_{k}={\frac {1}{2}}mv^{2}} E_{k}={\frac {1}{2}}mv^{2} (half mass times velocity squared). Then the total amount of energy can be found by adding {E_{p}+E_{k}=E_{total}} E_{p}+E_{k}=E_{total}.
 +
 
 +
Conservation of energy and mass in transformation
 +
Energy gives rise to weight when it is trapped in a system with zero momentum, where it can be weighed. It is also equivalent to mass, and this mass is always associated with it. Mass is also equivalent to a certain amount of energy, and likewise always appears associated with it, as described in mass-energy equivalence. The formula E = mc², derived by Albert Einstein (1905) quantifies the relationship between rest-mass and rest-energy within the concept of special relativity. In different theoretical frameworks, similar formulas were derived by J.J. Thomson (1881), Henri Poincaré (1900), Friedrich Hasenöhrl (1904) and others (see Mass-energy equivalence#History for further information).
 +
 
 +
Part of the rest energy (equivalent to rest mass) of matter may be converted to other forms of energy (still exhibiting mass), but neither energy nor mass can be destroyed; rather, both remain constant during any process. However, since {c^{2}} c^{2} is extremely large relative to ordinary human scales, the conversion of an everyday amount of rest mass (for example, 1 kg) from rest energy to other forms of energy (such as kinetic energy, thermal energy, or the radiant energy carried by light and other radiation) can liberate tremendous amounts of energy (~ {9\times 10^{16}} 9\times 10^{16} joules = 21 megatons of TNT), as can be seen in nuclear reactors and nuclear weapons. Conversely, the mass equivalent of an everyday amount energy is minuscule, which is why a loss of energy (loss of mass) from most systems is difficult to measure on a weighing scale, unless the energy loss is very large. Examples of large transformations between rest energy (of matter) and other forms of energy (e.g., kinetic energy into particles with rest mass) are found in nuclear physics and particle physics.
 +
 
 +
Reversible and non-reversible transformations
 +
Thermodynamics divides energy transformation into two kinds: reversible processes and irreversible processes. An irreversible process is one in which energy is dissipated (spread) into empty energy states available in a volume, from which it cannot be recovered into more concentrated forms (fewer quantum states), without degradation of even more energy. A reversible process is one in which this sort of dissipation does not happen. For example, conversion of energy from one type of potential field to another, is reversible, as in the pendulum system described above. In processes where heat is generated, quantum states of lower energy, present as possible excitations in fields between atoms, act as a reservoir for part of the energy, from which it cannot be recovered, in order to be converted with 100% efficiency into other forms of energy. In this case, the energy must partly stay as heat, and cannot be completely recovered as usable energy, except at the price of an increase in some other kind of heat-like increase in disorder in quantum states, in the universe (such as an expansion of matter, or a randomisation in a crystal).
 +
 
 +
As the universe evolves in time, more and more of its energy becomes trapped in irreversible states (i.e., as heat or other kinds of increases in disorder). This has been referred to as the inevitable thermodynamic heat death of the universe. In this heat death the energy of the universe does not change, but the fraction of energy which is available to do work through a heat engine, or be transformed to other usable forms of energy (through the use of generators attached to heat engines), grows less and less.
 +
 
 +
Conservation of energy
 +
Main article: Conservation of energy
 +
The fact that energy can be neither created nor be destroyed is called the law of conservation of energy. In the form of the first law of thermodynamics, this states that a closed system's energy is constant unless energy is transferred in or out by work or heat, and that no energy is lost in transfer. The total inflow of energy into a system must equal the total outflow of energy from the system, plus the change in the energy contained within the system. Whenever one measures (or calculates) the total energy of a system of particles whose interactions do not depend explicitly on time, it is found that the total energy of the system always remains constant.[11]
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 +
While heat can always be fully converted into work in a reversible isothermal expansion of an ideal gas, for cyclic processes of practical interest in heat engines the second law of thermodynamics states that the system doing work always loses some energy as waste heat. This creates a limit to the amount of heat energy that can do work in a cyclic process, a limit called the available energy. Mechanical and other forms of energy can be transformed in the other direction into thermal energy without such limitations.[12] The total energy of a system can be calculated by adding up all forms of energy in the system.
 +
 
 +
Richard Feynman said during a 1961 lecture:[13]
 +
 
 +
There is a fact, or if you wish, a law, governing all natural phenomena that are known to date. There is no known exception to this law – it is exact so far as we know. The law is called the conservation of energy. It states that there is a certain quantity, which we call energy, that does not change in manifold changes which nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says that there is a numerical quantity which does not change when something happens. It is not a description of a mechanism, or anything concrete; it is just a strange fact that we can calculate some number and when we finish watching nature go through her tricks and calculate the number again, it is the same.
 +
 
 +
— The Feynman Lectures on Physics
 +
Most kinds of energy (with gravitational energy being a notable exception)[14] are subject to strict local conservation laws as well. In this case, energy can only be exchanged between adjacent regions of space, and all observers agree as to the volumetric density of energy in any given space. There is also a global law of conservation of energy, stating that the total energy of the universe cannot change; this is a corollary of the local law, but not vice versa.[12][13]
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 +
This law is a fundamental principle of physics. As shown rigorously by Noether's theorem, the conservation of energy is a mathematical consequence of translational symmetry of time,[15] a property of most phenomena below the cosmic scale that makes them independent of their locations on the time coordinate. Put differently, yesterday, today, and tomorrow are physically indistinguishable. This is because energy is the quantity which is canonical conjugate to time. This mathematical entanglement of energy and time also results in the uncertainty principle - it is impossible to define the exact amount of energy during any definite time interval. The uncertainty principle should not be confused with energy conservation - rather it provides mathematical limits to which energy can in principle be defined and measured.
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 +
Each of the basic forces of nature is associated with a different type of potential energy, and all types of potential energy (like all other types of energy) appears as system mass, whenever present. For example, a compressed spring will be slightly more massive than before it was compressed. Likewise, whenever energy is transferred between systems by any mechanism, an associated mass is transferred with it.
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 +
In quantum mechanics energy is expressed using the Hamiltonian operator. On any time scales, the uncertainty in the energy is by
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 +
{\Delta E\Delta t\geq {\frac {\hbar }{2}}} \Delta E\Delta t\geq {\frac {\hbar }{2}}
 +
which is similar in form to the Heisenberg Uncertainty Principle (but not really mathematically equivalent thereto, since H and t are not dynamically conjugate variables, neither in classical nor in quantum mechanics).
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 +
In particle physics, this inequality permits a qualitative understanding of virtual particles which carry momentum, exchange by which and with real particles, is responsible for the creation of all known fundamental forces (more accurately known as fundamental interactions). Virtual photons (which are simply lowest quantum mechanical energy state of photons) are also responsible for electrostatic interaction between electric charges (which results in Coulomb law), for spontaneous radiative decay of exited atomic and nuclear states, for the Casimir force, for van der Waals bond forces and some other observable phenomena.
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 +
Energy transfer
 +
Closed systems
 +
Energy transfer can be considered for the special case of systems which are closed to transfers of matter. The portion of the energy which is transferred by conservative forces over a distance is measured as the work the source system does on the receiving system. The portion of the energy which does not do work during the transfer is called heat.[note 4] Energy can be transferred between systems in a variety of ways. Examples include the transmission of electromagnetic energy via photons, physical collisions which transfer kinetic energy,[note 5] and the conductive transfer of thermal energy.
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 +
Energy is strictly conserved and is also locally conserved wherever it can be defined. In thermodynamics, for closed systems, the process of energy transfer is described by the first law:[note 6]
 +
 
 +
{\Delta {}E=W+Q} \Delta {}E=W+Q
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 +
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 +
 +
 
 +
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 +
 +
 
 +
(1)
 +
 
 +
where {E} E is the amount of energy transferred, {W} W  represents the work done on the system, and {Q} Q represents the heat flow into the system. As a simplification, the heat term, {Q} Q, is sometimes ignored, especially when the thermal efficiency of the transfer is high.
 +
 
 +
{\Delta {}E=W} \Delta {}E=W
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 +
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 +
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 +
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 +
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 +
(2)
 +
 
 +
This simplified equation is the one used to define the joule, for example.
 +
 
 +
Open systems
 +
Beyond the constraints of closed systems, open systems can gain or lose energy in association with matter transfer (both of these process are illustrated by fueling an auto, a system which gains in energy thereby, without addition of either work or heat). Denoting this energy by {E} E, one may write
 +
 
 +
{\Delta {}E=W+Q+E.} \Delta {}E=W+Q+E.
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 +
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 +
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 +
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 +
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 +
(3)
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 +
Thermodynamics
 +
Internal energy
 +
Internal energy is the sum of all microscopic forms of energy of a system. It is the energy needed to create the system. It is related to the potential energy, e.g., molecular structure, crystal structure, and other geometric aspects, as well as the motion of the particles, in form of kinetic energy. Thermodynamics is chiefly concerned with changes in internal energy and not its absolute value, which is impossible to determine with thermodynamics alone.[16]
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 +
First law of thermodynamics
 +
The first law of thermodynamics asserts that energy (but not necessarily thermodynamic free energy) is always conserved[17] and that heat flow is a form of energy transfer. For homogeneous systems, with a well-defined temperature and pressure, a commonly used corollary of the first law is that, for a system subject only to pressure forces and heat transfer (e.g., a cylinder-full of gas) without chemical changes, the differential change in the internal energy of the system (with a gain in energy signified by a positive quantity) is given as
 +
 
 +
{\mathrm {d} E=T\mathrm {d} S-P\mathrm {d} V\,} \mathrm {d} E=T\mathrm {d} S-P\mathrm {d} V\,,
 +
where the first term on the right is the heat transferred into the system, expressed in terms of temperature T and entropy S (in which entropy increases and the change dS is positive when the system is heated), and the last term on the right hand side is identified as work done on the system, where pressure is P and volume V (the negative sign results since compression of the system requires work to be done on it and so the volume change, dV, is negative when work is done on the system).
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 +
This equation is highly specific, ignoring all chemical, electrical, nuclear, and gravitational forces, effects such as advection of any form of energy other than heat and pV-work. The general formulation of the first law (i.e., conservation of energy) is valid even in situations in which the system is not homogeneous. For these cases the change in internal energy of a closed system is expressed in a general form by
 +
 
 +
{\mathrm {d} E=\delta Q+\delta W} \mathrm {d} E=\delta Q+\delta W
 +
where {\delta Q} \delta Q is the heat supplied to the system and {\delta W} \delta W is the work applied to the system.
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 +
Equipartition of energy
 +
The energy of a mechanical harmonic oscillator (a mass on a spring) is alternatively kinetic and potential. At two points in the oscillation cycle it is entirely kinetic, and at two points it is entirely potential. Over the whole cycle, or over many cycles, net energy is thus equally split between kinetic and potential. This is called equipartition principle; total energy of a system with many degrees of freedom is equally split among all available degrees of freedom.
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 +
This principle is vitally important to understanding the behaviour of a quantity closely related to energy, called entropy. Entropy is a measure of evenness of a distribution of energy between parts of a system. When an isolated system is given more degrees of freedom (i.e., given new available energy states that are the same as existing states), then total energy spreads over all available degrees equally without distinction between "new" and "old" degrees. This mathematical result is called the second law of thermodynamics. The second law of thermodynamics is valid only for systems which are near or in equilibrium state. For non-equilibrium systems, the laws governing system's behavior are still debatable. One of the guiding principles for these systems is the principle of maximum entropy production.[18][19] It states that nonequilibrium systems behave in such a way to maximize its entropy production.[20]
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See also
 +
 +
Book: Energy
 +
icon Energy portal
 +
icon Physics portal
 +
Combustion
 +
Index of energy articles
 +
Index of wave articles
 +
Mattergy
 +
Orders of magnitude (energy)
 +
Power station
 +
Transfer energy
 +
Notes
 +
The second law of thermodynamics imposes limitations on the capacity of a system to transfer energy by performing work, since some of the system's energy might necessarily be consumed in the form of heat instead. See e.g. Lehrman, Robert L. (1973). "Energy Is Not The Ability To Do Work". The Physics Teacher. 11 (1): 15–18. Bibcode:1973PhTea..11...15L. doi:10.1119/1.2349846. ISSN 0031-921X.
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These examples are solely for illustration, as it is not the energy available for work which limits the performance of the athlete but the power output of the sprinter and the force of the weightlifter. A worker stacking shelves in a supermarket does more work (in the physical sense) than either of the athletes, but does it more slowly.
 +
Crystals are another example of highly ordered systems that exist in nature: in this case too, the order is associated with the transfer of a large amount of heat (known as the lattice energy) to the surroundings.
 +
Although heat is "wasted" energy for a specific energy transfer,(see: waste heat) it can often be harnessed to do useful work in subsequent interactions. However, the maximum energy that can be "recycled" from such recovery processes is limited by the second law of thermodynamics.
 +
The mechanism for most macroscopic physical collisions is actually electromagnetic, but it is very common to simplify the interaction by ignoring the mechanism of collision and just calculate the beginning and end result.
 +
There are several sign conventions for this equation. Here, the signs in this equation follow the IUPAC convention.
 +
References
 +
Harper, Douglas. "Energy". Online Etymology Dictionary. Archived from the original on October 11, 2007. Retrieved May 1, 2007.
 +
Smith, Crosbie (1998). The Science of Energy – a Cultural History of Energy Physics in Victorian Britain. The University of Chicago Press. ISBN 978-0-226-76420-7.
 +
Lofts, G; O'Keeffe D; et al. (2004). "11 – Mechanical Interactions". Jacaranda Physics 1 (2 ed.). Milton, Queensland, Australia: John Willey & Sons Australia Ltd. p. 286. ISBN 978-0-7016-3777-4.
 +
The Hamiltonian MIT OpenCourseWare website 18.013A Chapter 16.3 Accessed February 2007