Interstellar Hydrogen and Cosmic Background Radiation

It is shown that a collection of photons with nearly the same frequency exhibits a ”condensation” type of phenomenon corresponding to a peak intensity. The observed cosmic background radiation can be explained from this standpoint in terms of the radiation due to fluctuations in interstellar Hydrogen. In a previous communication[1] it was suggested that the origin of the Cosmic Background Radiation is the random motion of interstellar Hydrogen. We will now deduce the same result from a completely different point of view. We start with the formula for the average occupation number for photons of momentum ~k for all polarizations[2]: 〈n~k〉 = 2 eβh̄ω − 1 (1) Let us specialize to a scenario in which all the photons have nearly the same energy so that we can write, 〈n~k〉 = 〈n~k′〉δ(k − k ′), (2) where 〈n~k′〉 is given by (1), and k ≡ | ~k|. The total number of photons N , in the volume V being considered, can be obtained in the usual way,