Seeing through opaque objects is notoriously hard. Unless you have Superman’s “X-Ray vision”, or those “X-Ray specs” that for decades have promised teen voyeurs the ability to see through clothes. What would be the physics of that? And is it at all possible to have X-Ray vision?

X-Rays are nothing but light with very short wavelength, for which skin and flesh are mostly transparent. Which is how X-Ray scans do their thing.

So “X-Ray vision” became a shorthand for “seeing through objects”. But doing it in classic Superman-style has a fundamental problem: that’s not how vision works. We don’t shoot rays out of our eyes, it’s more about light rays going in*. So that doesn’t quite work out.

Surprisingly, X-Ray goggles make more sense.

We could imagine, for example, a set of specs that takes in X-Ray light and turns it into visible colors. It would be like what thermal cameras do: they measure infrared light and express that in terms of some arbitrary range of colors visible and understandable for us.

Of course, that’d be some high-tech gear. So—guess what—those 10 bucks “X-Ray goggles” don’t actually work.

Even if we had real, working X-Ray goggles, we wouldn’t see much. The Sun emits a whole lot of light, that bounces off all sorts of things for us to see. But hardly any X-Rays, and the atmosphere absorbs most of it.

X-Ray cameras of sort are already on the market, mostly for security and law enforcement. They work basically like a news reporter setup: a powerful light (in this case X-Rays) shines on an object, and a camera records what bounces off. Different materials reflect X-Rays differently so you can see, say, the content of an abandoned backpack.

Superman’s vision could work if he somehow emitted exactly enough X-Rays (or whatever other radiation) to penetrate what he needs to see through and reflect off what’s behind. Still, the dude got superpowers—he need not care about physics.

If you want more

• On Wired they had some fun imagining how several supervisions could work
• If you are still fixated on seeing through clothes (you perv), your best bet is a body scanner, but that’s a different story
• How do “X-Ray specs” work?

 

Cover photo: gratisography.com

*Before you ‘well actually’ me on this: yes, more modern understandings of Superman’s powers seem subtler than that. But that’s a bit beside the point.