A few years ago when I was doing my Physics A-Level, me and a few others took part in a competition in which we had to perform a short play that educated a group of non-scientists about a something to do with physics. We chose refraction and showed how a laser bent in a fish tank at different angles. At the end of the play, the panel asked us questions. Being the person in the group that knew most about refraction, I took the lead on answering them. One of the questions completely stumped us and even our teacher. I think the exact question was the following: The best answer I've had from anyone I've asked has been a rather vague (and possibly blabbering) "I think it's got something to do with how the constituents of light interact at a quantum level". So, anyone got an answer for me?