[dzdt]

The correlation between 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 indeed "funny". The match seems close enough to be worth investigation.

On the other hand the observation that "This value coincides with the critical temperature of equilibrium between the respective densities of radiation and matter in the early universe" seems spurious and is unsupported by anything in the paper.

I would expect rather there is some quirky statistics that happen with the quantum mechanics of orbitals that gives a similar shaped distribution of frequency of occurrence of spectral lines to the Boltzman distribution.

There is probably an interesting statistical story to tell, but I don't see the connection to the early universe as a supported thing here.

[SiempreViernes]

Part of explaining this "funny" coincidence is going to be how one motivates their selection cuts, like the choice to use only one database instead of crossmatching several for better robustness [1]. The choice to ignore higher ionisations, the choice to ignore any systematic effects from the fact that the heavier elements, with their shorter wavelengths, are just downright harder to work with experimentally.

Finally, what do our current best atomic models predict that this distribution should be? These authors seem to think nobody models atomic spectra...

[1] See here for one such effort of comparing various databases: https://www.aanda.org/articles/aa/full_html/2018/04/aa31933-...

[tzs]

> The correlation between 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 indeed "funny". The match seems close enough to be worth investigation.

"The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka' but 'That’s funny...'" —Isaac Asimov

[uoaei]

The universe is at equilibrium in the sense that transitions from energy to matter and vice versa are more or less balanced at the scale of the universe. So the critical temperature of equilibrium between densities of radiation and matter in the universe writ large would appear to be well-approximated by the global temperature of the universe at any point in time except for those times near the Big Bang itself.