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earanhart t1_j6vh38v wrote

Physics: Given that the speed of light changes based on the medium through which the light travels, can matter or energy move faster than its local light if in some highly refractive or dense medium?

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Luenkel t1_j6vkhna wrote

Yes, this most famously happens in nuclear reactors where emitted electrons move through the water at speeds greater than light does. This creates the blue glow you might be familiar with through cherenkov radiation, a phenomenon analogous to a sonic boom.

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earanhart t1_j6vn1mz wrote

I thought that was "watching photons slow down". It's actually the beta radiation doing it? How cool.

Thank you.

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mfb- t1_j6w03ul wrote

Beta radiation is electrons. They are moving through the water faster than light can move through it. That leads to the emission of Cherenkov radiation, which is mostly blue in most cases (including water).

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