Determining Evolution of Cosmological Constant, Gravitational Constant and Speed of Light Using Nonadiabatic Cosmological Model and LLR Findings

We have shown that the Hubble constant $H_0$ embodies the information about the evolutionary nature of the cosmological constant $\Lambda$ , gravitational constant $G$ , and the speed of light $c$ . We have derived expressions for the time evolution of $G/c^2 \left(\equiv K\right)$ and dark energy density ${\epsilon }_{\Lambda }$ related to $\Lambda$ by explicitly incorporating the nonadiabatic nature of the universe in the Friedmann equation. We have found $\left(dK/dt\right)/K = 1.8H_0$ and, for redshift $z$ , ${\epsilon }_{\Lambda ,z}/{\epsilon }_{\Lambda ,0} = {\left[0.4+0.6{\left(1+z\right)}^{-1.5}\right]}^2$ . Since the two expressions are related, we believe that the time variation of $K$ (and therefore that of $G$ and $c$ ) is manifested as dark energy in cosmological models. When we include the null finding of the lunar laser ranging (LLR) for $\left(dG/dt\right)/G$ and relax the constraint that $c$ is constant in LLR measurements, we get $\left(dG/dt\right)/G = 5.4H_0$ and $\left(dc/dt\right)/c = 1.8H_0$ . Further, when we adapt the standard $\Lambda$ CDM model for the $z$ dependency of ${\epsilon }_{\Lambda }$ rather than it being a constant, we obtain surprisingly good results fitting the SNe Ia redshift $z$ vs distance modulus $\mu$ data. An even more significant finding is that the new $\Lambda$ CDM model, when parameterized with low redshift data set ( $z < 0.5$ ), yields a significantly better fit to the data sets at high redshifts ( $z > 0.5$ ) than the standard ΛCDM model. Thus, the new model may be considered robust and reliable enough for predicting distances of radiation emitting extragalactic redshift sources for which luminosity distance measurement may be difficult, unreliable, or no longer possible. View Full-Text