Possible Link between the Distribution of Atomic Spectral Lines and the Radiation-Matter-Equilibrium in the Early Universe

The uncanny resemblance of the global distribution of all experimentally known atomic spectral lines to the Planckian spectral distribution associated with black body radiation at a temperature of 𝑇≈9000K is reported. This value coincides with the critical temperature of equilibrium between the respective densities of radiation and matter in the early universe.