posted on Oct, 14 2009 @ 08:42 AM
Originally posted by dragonridr
...we can slow down the speed of light and discovered that light resumes its previous speed again once it passed through the gas. This still confuses
me where does light get the energy to speed back up again?
That's because slowing down the speed of light DOES NOT mean slowing down the speed of photons.
The way light slows down in a medium is this:
- Light (photons) traveling the "normal" speed of light enter the medium and get adsorbed by the atoms in that medium. This absorption of a photon
increases the energy of the atom, which will then emit another photon -- and this photon is also going the "normal" speed of light, until it hits
another atom which absorbs it/increases energy/emits another photon.
- This absorbtion/emitting of photons by the atom takes some time. The accumulated time delay is what makes the light slow down. However, the
individual photons never slow down -- they are always moving at the "normal" speed of light
- The last atom on the other side of the medium absorbs a photon then emits a photon, and that photon is traveling the "normal" speed of light.
THEREFORE on the other side of the medium, light continues at its normal speed.
The photons are not really "passing through" the medium. They are getting absorbed by each atom and identical photons are being emitted.
So the photons themselves are not really slowing down -- it is just taking longer for the energy wave
of the light to pass through the
The slowing down of a light wave is not new and its not hard. We see it happening all the time in water and eyeglasses. The refraction (bending) of
the light in water and lenses is caused by the light slowing down through the medium. What these scientists are doing is controlling the speed more
[edit on 10/14/2009 by Soylent Green Is People]