Black Body 10 Photon Gases

Описание: This video uses the "light is particles" heuristic to compare the physics of photon gases to gases of atoms. It looks at particle numbers, pressure, volume, and temperature effects.

The next video on Stefan-Boltzmann's law is in production. It should be on YouTube in March, 2014.

The Wikipedia article on photon gases is a good reference.

I used the textbook "Statistical Mechanics" by Pathria and Beale for much of the discussion on particle numbers, fluctuations, and equations of state.

The remarks on tracking photons and photon size come from quantum field theory books. My favorite is Weinberg's "Quantum Theory of Fields, Volume 1". The statements that photons can't be tracked and don't have a size is easiest to see from Feynman diagrams. One wavy photon line comes in to each vertex, and no wavy photon lines go out.

The statement that the density fluctuation of atoms gases is zero applies to the fluctuation of the number of atoms in the entire container. For a sub-section of the container, the fluctuation is not zero, but goes as the square root of the number of particles. It's still a very small number.

The statement that fluctuations in the photon density are infinite could indicate that one or more of the assumptions of statistical physics and the grand canonical ensemble are wrong. I would welcome a good discussion on this topic.