Underwater nuclear reactor test, where Cherenkov radiation is the result of the experiment.
A nice reminder that, contrary to the sickly green you usually see in fiction, glowy radiation is usually a lovely blue. But what’s happening? Well, something’s going faster than light! I’m not a physicist, so i might be getting some details wrong, but this is as far as i understand it:
See, the speed of light is a universal constant, the c of e=mc². But that’s only in a vacuum—so much of physics is based first and foremost on activity in a vacuum—and the speed of light through matter is often significantly slower. Instead of 1 c, light moves through liquid water at about 0.75 c. That may still be ludicrously fast, but it’s still slowed down enough that charged particles like electrons can exceed that speed within the medium in question. Exceeding that speed does all kinds of weird, somewhat terrifying and very exciting things to the electromagnetic field of the medium, including the creation of a shockwave in a manner very similar to a sonic boom.
In other words, that bright blue visible radiation is what happens when a particle exceeds the speed-of-light-in-water and creates a luminal boom.
Oh. So THAT’S what my favorite color is
