I Light Speed in Dense Medium: Explained

[deedee6905]

TL;DR

Does light travel at the same speed?

If light goes from air through glass, the reason the light bends is because I'm told that the light travels slower inside the glass. If I change my observer reference to inside the glass, the speed of light inside the medium it look like light is still traveling at the speed of light? if so, the light from outside then would have to look like it is traveling faster than the speed of light. How does this actually work?

 

[Ibix]

Light only maintains its invariant speed $c$ in vacuum. It travels slower in media. Particles are routinely observed traveling faster than light in a medium (although never faster than $c$). They slow down by emitting Cerenkov radiation.