> Oh but the speed of the signal does depend quite a lot on the transmission medium And this (actually, phase velocity) is what makes refraction a thing. I kn

> Oh but the speed of the signal does depend quite a lot on the transmission medium And this (actually, phase velocity) is what makes refraction a thing. I knew that we could slow down light to subsonic speeds, but TIL we can put it at a complete standstill! Amazing. https://en.wikipedia.org/wiki/Speed_of_light#In_a_medium https://en.wikipedia.org/wiki/Speed_of_light#In_a_medium