Percy writes:
This article does not make clear that the speed of light is not actually slower in a refractive material. For example, photons in glass do not travel more slowly. The speed of light remains precisely the same, it is just that it takes time for photons to be absorbed and retransmitted, and that extra time is what makes the light appear to travel more slowly. But with few exceptions, the light emerging from the other side of glass consists of different photons from the ones that entered.
Wow - Some heavy enlightenment (no pun intended).
You have a reference for futher reading on that?
Moose
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