Friedmann type equations in thermodynamic form lead to much tighter constraints on the critical density of the universe
Espen Gaarder Haug, Eugene Terry Tatum
Abstract
Abstract Based on recent progress in cosmological thermodynamics, we present a new thermodynamic 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 accurately 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. Our results are consistent with $$R_{H_t}=ct$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>R</mml:mi> <mml:msub> <mml:mi>H</mml:mi> <mml:mi>t</mml:mi> </mml:msub> </mml:msub> <mml:mo>=</mml:mo> <mml:mi>c</mml:mi> <mml:mi>t</mml:mi> </mml:mrow> </mml:math> cosmology that recent observations from JWST appear to support.