From FAQ: IS LIGHT A WAVE OR A PARTICLE?

[erickalle]

So when a photon encounters a solid, and it can interact with an available phonon mode (i.e. something similar to a resonance condition), this photon can be absorbed by the solid and then converted to heat (it is the energy of these vibrations or phonons that we commonly refer to as heat).

Thanks for the great answers but unfortunately for you, people always want to know more.

We know that phonons greatly alter electrical behaviour of metals at different temperatures.
Why isn’t there a change in behaviour with temperature regarding light properties such as described in the answer.
I’ve never looked through glass at around zero K but I imagine it never becomes opaque at any temperature.

 

[ZapperZ]

Thanks for the great answers but unfortunately for you, people always want to know more.

We know that phonons greatly alter electrical behaviour of metals at different temperatures.
Why isn’t there a change in behaviour with temperature regarding light properties such as described in the answer.
I’ve never looked through glass at around zero K but I imagine it never becomes opaque at any temperature.

Because within the framework of the naive case being described, the phonon density of states are not affected by the temperature of the dielectric. Since the phonon states are the only factor in light propagation through this simple medium, you get no significant difference with change in temperature within any reasonable limits.

This of course does not describe ALL materials since there are always exceptions to the simplest case.

Zz.