Monday, April 12, 2010 10:39:09 AM
To be clearer - the photons are going at the speed of light. The light seen by an observer (not the original photon that entered the material) propogates more slowly.
The freaky thing is, from the photons frame of reference, it gets at where it has been instantly, regardless of the distance. Nanometer or 1000 light years, all just the same to the photon..
Monday, April 12, 2010 10:31:36 AM
I'll beg to differ on that one, you`re talking about speed of propogation - not the actual speed of the light. You`ve taken into account the absorption, re-radiation and refraction effects. The actual light is still going at c between the atoms.... Semantics maybe, but light does not go at any other speed. We just perceive the effects as slower.
Monday, April 12, 2010 5:10:28 AM
Light is *the* thing that *always* travels at *that* speed regardless of the reference frame.
It can't go at any other speed...
Light can be slowed down a lot. Its speed depends on the material it is passing through. Physicists have been deliberately slowing it down more than naturally occurs for some time now and a few years ago one of them (Lene Vestergaard Hau) managed to slow it to zero.
Light only travels at c when there is nothing to slow it down, i.e. in a vacuum.