Faster-than-light in a medium, which slows light down. Not faster than c, which I believe is the point Einstein et al were making when fixing the speed limit of

Faster-than-light in a medium, which slows light down. Not faster than c, which I believe is the point Einstein et al were making when fixing the speed limit of the universe. Although a lighthearted joke about “sciencing hard” being invariant certainly flew off its rails just as fast.:p