Light through a dense material

[thehangedman]

As light moves through a dense material, it would interact with the atoms. Would the light lose energy, on average, in the process? As a result, would we observe a red-shift as it moves through?

If so, what is the relationship between the amount of red-shift (energy lost) to the distance of material being traversed?

 

[DrDu]

The dominant mechanism for energy loss is usually light quanta being completely absorbed.
A red shift results on the mean e.g. from Raman scattering.

 

[Claude Bile]

Energy in a wave is lost because the number of photons decreases (as opposed to the energy per photon decreasing) through absorption and scattering.

Raman scattering can red-shift photons but this effect is extremely weak.

Claude.

 

[DrDu]

The authors of

http://www.nature.com/nature/journal/v468/n7323/full/nature09567.html

use photon number conserving scattering to cool the photons until they consense into a Bose Einstein Condensate.