Friedmann Type Equations in Thermodynamic Form Lead to Much Tighter Constraints on the Critical Density of the Universe

Espen Haug; Eugene Tatum

doi:10.20944/preprints202403.1241.v2

Preprint Article Version 2 Preserved in Portico This version is not peer-reviewed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 present a new thermody- namic formulation of the Friedmann equations in the new Haug-Tatum cosmology model, as well as for other similar models put forward in the literature from different solutions to Einstein’s field equation. Since the CMB temperature has been measured much more accu- rately than the Hubble constant, we demonstrate that our thermodynamic formulation of the Friedmann equation dramatically narrows the acceptable range for the critical density of the universe. Furthermore, we show how our thermodynamic formulation leads to a more precise cosmological constant estimate.

Friedmann equations, FLRW, Universal critical density, Cosmological con- stant, Haug-Tatum model, Extremal solution, Haug-Spavieri solution, Flat space cosmology

Physical Sciences, Astronomy and Astrophysics

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Friedmann Type Equations in Thermodynamic Form Lead to Much Tighter Constraints on the Critical Density of the Universe

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