The past few years have been really exciting for the (previously small) intersection of pure mathematics and materials science. It turns out that Cloaking (yeah, Klingons and stuff) is actually a real thing that people are doing. Now we're not at the scale of spaceships or anything (actually we took a step backwards as far as spaceships are concerned this week).


The mathematicians have been all over this one, and so have the materials scientists. Now the state of the art isn't going to blow you away: we are only able to cloak a thin region of the spectrum (we can only cloak a tiny range of "colors" at once right now), we have only been able to cloak really tiny things (but that's not an actual obstruction, I hear). However, the first new 3D cloaking device was unveiled a couple of months ago. I heard about this breakthrough first on the radio and remember cheering because It's really exciting to see things you can scribble on a sheet of paper actually come to life.

Anyway, I employed a great deal of technology to bring you some pictures of how it works, assuming you don't know what nanomaterials are or any of that differential equations stuff (in which case you ought to read some of those crazy math/physics papers).

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First, the physics of how large, slow things - like planets and baseballs - move is governed by Newton, who said stuff moves in straight lines except when other stuff gets in the way. Einstein came along and said, "Yeah, that's right, except that the lines the universe thinks are straight don't really agree with our traditional notions." (Image search "gravitational lensing" if you want to see some really cool graphics.)

Ignore for a moment that light, etc., moves much faster than baseballs, because velocity really doesn't have a lot to do with the cartoon version of this story. So here we have space, with its perfectly straight lines:



Now if you poke a hole in space by removing just one point, then it looks the same and physics behaves the same. There's some fancy math that makes this true, but it at least sounds true, and that's what's really important.



Next, we stretch that point to a big old hole.



If you're playing along at home, don't actually tear a hole in space. It's a bad idea.



Instead, what we just did was create a description of what the straight lines look like outside our little bubble. If you can impose some type of physics on this little region of the universe in which things which think they're traveling in a straight line actually curve and swoop around our bubble, you've effectively created a cloak for that bubble. This is what people are doing.

Two things about this weird me out. The first is that it's not just about placing mirrors in a way to deflect light around the hole. The straight lines have LENGTHS, and the length of the lines in the last picture need to be the same as the lengths of the lines in the first picture or else you're in big trouble. This is the hard part about going from the first to the last picture.

The second thing is the impracticality. If you're actually using this type of process to hide from the Federation, you aren't going to be able to see out. All of the light that is outside the bubble stays outside the bubble. It's like a really lame version of Las Vegas. So if you ever do manage to build a cloaking device, you should probably bring a flashlight along with you.

JC - AoPS