The ΛCDM-NG Cosmological Model: A Possible Resolution of the Hubble Tension

Abstract

We offer a cosmological model based on conventional general relativity (no speculative physics) that may resolve the Hubble tension. A reanalysis of the foundation of the Lambda-CDM model shows that general relativity alone does not specify what fraction of the mass density acts as the source term in Friedmann’s equation and what fraction acts as the source of the gravitational potential of condensed objects. This observation opens the way to alternative cosmological models within conventional general relativity, and it proves that the ΛCDM model is not the unique solution of Einstein’s equations for the usual cosmological sources of gravitation. We emphasize that the source of the gravitation potential in the ΛCDM model is the deviation δ ρ m of the mass density away from its average value, and not the total density of condensed masses as in Newtonian theory. Though not often stated, this is a modification of Newtonian gravitation within the ΛCDM model. The ΛCDM-NG model uses the freedom to move matter between source terms to restore the source of gravitational potential to its Newtonian form. There is no Hubble tension in the ΛCDM-NG model if the gravitational potential of condensed objects (stars, galaxies, and dark matter clouds) falls in a certain range, a range that does not seem unreasonable for the actual Universe. The deceleration parameter in the ΛCDM-NG model differs from that in the ΛCDM model, suggesting a test to distinguish between the two models.