Friedmann Type Equations in Thermodynamical Form Lead to Much Tighter Constraints on the Energy Density of the Universe

Espen Haug

doi:10.20944/preprints202403.1241.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 20 March 2024 / Approved: 20 March 2024 / Online: 20 March 2024 (16:58:34 CET)
Version 2 : Received: 23 March 2024 / Approved: 26 March 2024 / Online: 26 March 2024 (10:51:27 CET)

Based on recent progress in cosmological thermodynamics, we are presenting a new ther- modynamic formulation of the Friedmann equations, as well as for other similar equations put forward in the literature from different solutions to Einstein’s field equation. Since the CMB temperature has been measured much more accurately than the Hubble constant, we demonstrate that the thermodynamic formulation of the Friedmann equation dramatically narrows down the acceptable range for the mass-energy density in the universe.

Friedmann equations, FLRW, energy density universe, extremal solutions, Haug-Spavieri solution.

Physical Sciences, Astronomy and Astrophysics

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Friedmann Type Equations in Thermodynamical Form Lead to Much Tighter Constraints on the Energy Density of the Universe

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