Remember when you were a little boy, killing small animals with knives and building fortresses out of dirt and sticks? Girls (55 percent of my audience), you can ignore this part. Anyway, the inevitable discussion that every single small boy has ever had is the following: if you could have any superpower, what would it be?
And equally inevitably, someone said invisibility. Whether it was just our perverted young minds yearning for any way to see some boobies or just because it’d be way easier to kill small animals with knives if they couldn’t see you coming, the idea of being invisible was incredibly appealing.
Now, scientists have found a way to make it happen. But don’t get too excited.
First, it’s science time. The way these things work is by exploiting the property of light that actually got Einstein his Nobel Prize, not all the other crap you’ve heard of him for.
It’s called particle-wave duality, and it means that sometimes light behaves like a wave and sometimes it behaves like a particle. One of the cool things that that means is that light can be bent like a wave. And we know a hell of a lot about how to manipulate waves. Imagine a wave is coming toward you, be it an ocean wave or a light wave (this doesn’t work on sound because that’s a different kind of wave). You refract the wave around you and reassemble it on the far side of you so that it looks the same as it did before it hit you. Yes, it was disrupted, but now imagine there’s someone on the far side of you who’s trying to tell, only by looking at the wave, whether there’s anything (you) in the way. If the wave looks like it did before it met you, they have no way of knowing you’re there. Here’s a picture.
That’s how these invisibility “cloaks”—as they’re called, though they’re more like blocks of what looks like glass—work. They are made of unique materials with what’s called a negative index of refraction, and it doesn’t really matter what that means, but they can do this.
That roll of pink paper is, for all practical purposes, invisible. Even instruments wouldn’t be able to tell that there’s something there.
There are two catches. The first is that right now, this system and material only work with light that’s all oscillating in the same direction. That’s called polarized light, and it’s easy to do, but basically none of the light that occurs in nature is like that. So if you put the little pink roll of paper out in the sun, you’d see it clearly. That’s the kind of problem that can probably be fixed.
The second catch is more serious and cannot be avoided. I think we can all agree that the end goal of making something invisible is so that you can use it to sneak up on things. Maybe it’s a plane that can fly low and take super-hi-res spy shots, maybe it’s a Navy SEAL doing recon on an enemy base, maybe it’s just a remote-control car with a camera on it. None of that will work, for one reason: if you’re invisible, you’re also blind.
That’s right, kiddies. Blind. And that doesn’t make you very useful for spy work or booby-sighting or small-animal-assaulting. You see, the way our eyes work is by taking in light, where it’s absorbed in the back of the eye and turned into an electrical signal that the brain interprets as an image. Now imagine you’re that little pink piece of paper. The light that was bound for you, the light that would have enabled you to see whatever it was coming from, is intercepted. Busy little calcite crystals bend it around you and out the back of your “head,” and it never touches you. You never see it. And that’ll always be the case. If you don’t want the light coming at you to hit you—and you don’t, because then it’ll scatter and you’ll become a light source and then you’re not invisible—then you can’t use it either. You can’t see.
The (Possible) Solution
So yes, part of you has to be visible if you’re going to have any use at all. But technically, you could have a suit that renders all of you invisible except for two little eye holes and see through those. From the front, people would just see eyes floating, which are much smaller than, say, a whole person. And from the back there’d be a whole in the image that would be easy to fill in in a similar manner to Photoshop’s intelligent delete thing. Just blur the edges. By the same token, you could make the whole spy plane invisible except for the camera lens and so on.
Another idea that no one really talks about (because it’s wildly impractical) is active camo, as seen in Halo and a billion other video games. Usually, that’s explained by tiny cameras on one side of your suit and essentially a screen on the other side, but that’s basically impossible to pull off, given the variety of view angles and resolution and brightness and stuff. What it boils down to is that you can’t make something invisible if you want it to be able to see.
The Real Solution
But who cares? What if you’re on the receiving end of those spy photos, for example. Say you have a phalanx of tanks or aircraft out on some airfield. What if you could just put some kind of calcite cover over them and then you wouldn’t have to hide them? Planes overhead, people on the ground, no one would have a clue the thing was there until you pulled the cover off. Same goes for anything, anywhere. The other thing is that this doesn’t have to be used for visible light. You could use it to divert dangerous x-rays around doctors to reduce exposure. You could use it to divert x-rays around astronauts on long spaceflights. It could divert light around the crossbars in telescopes to eliminate diffraction spikes and make for better optics.
It could divert radio around skyscrapers to improve cell reception in cities. Perhaps most awesomely, a similar system uses posts to do the same thing with ocean waves. That means you can build an oil refinery, arrange this pattern of giant pilings around it, and it will always experience calm water. You could even use it on shore to divert waves away from a dock. The diverted waves would pound the shit out of the shoreline around you, but that’s fine.
The Bottom Line
This is still awesome. It’s still basic science, something that is almost always less interesting because it doesn’t have a goal behind it. It’s just “let’s see what happens” science. And the research that’s happened here is expanding our knowledge of the way light works. There’s no way that won’t be useful. All I’m saying is not to get your hopes up quite yet.