The authors have a look at the spectral line database of the NIST and make the surprising finding, that all atomic spectral lines together approximate very well

The authors have a look at the spectral line database of the NIST and make the surprising finding, that all atomic spectral lines together approximate very well a black body spectrum at a temperature of 9000K. The authors not yet have an explanation for this conundrum, but also note, that this temperature plays a role in the formation theory of the universe.