Slow Light?

[lord twiggy1]

the other weekend, I was watching an episode of The Universe about the speed of light. In it, they were talking about how they could slow the speed of light by making it go through a dense concentration of some kind of atom (I can't remember which element). I don't exactly get that. Can anyone explain this to me?

[Klaus]

I would also like to know. I have read that the speed of light is always constant.

[xalos]

What the substance mentioned something like a neutron star?
p.s. there's also the element osmium, which is the most dense on the periodic table,so.....

[Nowhere Man]

The speed of light in a vacuum is a constant, the one we all know and love as c.

The speed of light in a material medium, like air, glass, water, etc. is slower but still darn fast. Look up refraction and speed of light in Wikipedia.

This might be what you heard about. It's recent, but physicists have been working on slowing down light for some time.

Fred

[sabianq]

what fred is saying is that the speed of light is a constant, always.

very (very very) basically,
what happens in reality say when a light beam hits the surface of water and refracts, the over all velocity is slower, which is why it refracts. what is happening on a quanta level, is the photon hits the electron shell of the atoms in the water (or other substance, say air or glass) the electron absorbs the photon and holds onto it as a higher or excited state of energy, this takes a bit of time (not much) then the electron falls back to its initial energy state(conserving energy) and releases a photon that is equal in every way to the photon that hit it. (i wonder if the photon that is released is an exact copy or if it is the original, )

this happens along the entire path, which slows down the light beam then the light beam refracts.


as the photon passes between electron clouds, the velocity is the speed of light.

it is just easier to give the velocity change in a medium as compared to the speed of light in a vacuum.

it is possible to create a medium where the photon can be "held" in an excited energy state for very long periods of time and even released on demand and in a different direction.

this would make optical computers a reality..

check out slow light
http://en.wikipedia.org/wiki/Slow_light

Light traveling within a medium is no longer a disturbance solely of the electromagnetic field, but rather a disturbance of the field and the positions and velocities of the charged particles (electrons) within the material. The motion of the electrons is determined by the field (due to the Lorentz force) but the field is determined by the positions and velocities of the electrons (due to Gauss' law and Ampere's law)). The behavior of a disturbance of this combined electromagnetic-charge density field (i.e. light) is still determined by Maxwell's equations, but the solutions are complicated due to the intimate link between the medium and the field.