Question: What is the best way you can explain total internal reflection

Duncan McNicholl answered on 8 Nov 2017:

This is a much harder question than I thought it was. The best I’ve got for you is that refraction happens when the light speeds up on its way out of the glass or whatever, and the bigger the angle of incidence the more bending the light does, because one side has been out of the glass for longer than the other, and so has been travelling faster for longer, until the light has to bend so much on its way out of the glass that it just can’t sustain it, and so it stays inside the glass instead. There’s another explanation involving a lot of maths and imaginary numbers, but that’s more of a mathematical description than a real explanation. I’m going to be thinking about this a lot now.