It's been argued that light travels at the speed of light in vacuum when it is travelling slower through an optically denser material. The stated logic is, and its Physically correct, that the photons are travelling at the same speed as that of light in vacuum, getting absorbed by the molecules of the medium and re-emitted after a small delay.
Semantically, I don't find it convincing. If a rabbit sleeps and pauses every few yards to end up being slower on average than a turtle, I wouldn't call its speed whatever it is that it travels at in between frequent sleeps.
moves at the speed of light even at rest! Wow... this is enticing.
It's been argued that light travels at the speed of light in vacuum when it is travelling slower through an optically denser material. The stated logic is, and its Physically correct, that the photons are travelling at the same speed as that of light in vacuum, getting absorbed by the molecules of the medium and re-emitted after a small delay.
Semantically, I don't find it convincing. If a rabbit sleeps and pauses every few yards to end up being slower on average than a turtle, I wouldn't call its speed whatever it is that it travels at in between frequent sleeps.