sci.physics.research

On 2007-08-26, goombaj@ wrote:
> Is the photon entropy independent of its frequency? does it remain
> constant? I am trying to work out the photon gas entropy using such a
> postulate. Is this well justified? Please cite sources wherever
> possible

Entropy is not a property of a particle, it is a statistical property of
ensembles of particles (or other things). However, provided the wording
of the question is sorted out, it can be answered by analogy: the
"entropy of a photon" depends on its frequency just like the "entropy of
a massive particle" depends on its energy. The idea here is that, if you
want, you can treat a photon in the same way as a massive particle, but
taking the mass -> 0 limit in the end. So, can you answer your own
question if you replace "photon" by "massive particle"?

Now, calculating the entropy of a photon gas can be a tricky thing. It
involves dealing with statistical mechanics of a relativistic system.
Here's another question to ponder. Do thermodynamic properties of a
photon gas depend on the number of photons in it? The question is
intentionally vague. :-)

Igor