Speed of light /time / and material

[renegade05]

Alright, I have a noddle scratcher..at least for me.

I understand light can slow down and speed up as it moves through different materials. I know light cannot exceed the speed of light (c). I know at the speed of light time is instantaneous or stops - same difference.

So my question is this: since light slows down when going through material, such as glass, what would the photon observe? and what would we observe?

Like, a photon of light leaves the sun at speed c then goes through a piece of glass at (2/3)c and exists the glass at speed c again?

First, isn't light always at speed c? how can we possible observe light at (2/3)c. Or is the theory that the speed of light is always the same relative to everything else? So someone outside the glass would see the light at (2/3)c and someone moving inside the glass would observe it at the same speed (2/3)c?

Second, what the heck would this photon experience. Would it be instantaneously brought to the glass and not experience time, and then as it moves through the glass all of a sudden experience time, and then no time as it moves at c again as it exists?

Which leaves me to my big picture question? Is a photon usually moving less than (c) since it is hardly moving through a perfect vacuum? If so, most photons do experience time?

I am just trying to figure out what happens as photons move through stopped time to some slow time as they change speed.

I hope I articulated what I am trying to ask. Please help!

 

[JesseM]

In the "General Physics Forums" there's a thread called Physics Forums FAQ, see post #4 on that thread--at a micro level, what's happening is that photons are repeatedly getting absorbed and re-emitted by the material of the medium, they still always travel at c between absorptions.

 

[Elias Y Daoud]

In the "General Physics Forums" there's a thread called Physics Forums FAQ, see post #4 on that thread--at a micro level, what's happening is that photons are repeatedly getting absorbed and re-emitted by the material of the medium, they still always travel at c between absorptions.

Dear Jesse,I don't think so that the matter absorb and re-submit the photon. If this occur who can confirm that the nucleus or electron (usually) absorb the photon will re-submit it by 180 degree knowing that the atom and electron moving randomly. The light will deviate and take undefined direction as diffusion.

 

[JesseM]

Dear Jesse,I don't think so that the matter absorb and re-submit the photon. If this occur who can confirm that the nucleus or electron (usually) absorb the photon will re-submit it by 180 degree knowing that the atom and electron moving randomly. The light will deviate and take undefined direction as diffusion.

Please read the FAQ article I linked to, it's not that the individual atoms are absorbing and re-emitting photons, rather it's that "collective vibrational modes" of the material are doing the absorption and emission (a quantum-mechanical phenomenon).

 

[Elias Y Daoud]

Please read the FAQ article I linked to, it's not that the individual atoms are absorbing and re-emitting photons, rather it's that "collective vibrational modes" of the material are doing the absorption and emission (a quantum-mechanical phenomenon).

Thank you, I read this. I'm new :) to this site, so I have to discover it first.
Thanks