Singularities of varying light speed cosmologies

TL;DR

This paper investigates the singularities in isotropic cosmological models with varying light speed and gravitational constant, analyzing their dynamics and the nature of resulting singularities using phase space and asymptotic methods.

Contribution

It introduces a detailed analysis of singularities in varying light speed cosmologies using dynamical systems and asymptotic splittings, expanding understanding of their behavior.

Findings

Closed models recollapse to future singularities

Open models expand eternally towards the future

Nature of singularities depends on model parameters

Abstract

We study the possible singularities of isotropic cosmological models that have a varying speed of light as well as a varying gravitational constant. The field equations typically reduce to two dimensional systems which are then analyzed both by dynamical systems techniques in phase space and by applying the method of asymptotic splittings. In the general case we find initially expanding closed models which recollapse to a future singularity and open universes that are eternally expanding towards the future. The precise nature of the singularities is also discussed.