The Local Effects of Cosmological Variations in Physical 'Constants' and Scalar Fields II. Quasi-Spherical Spacetimes

TL;DR

This paper demonstrates that local measurements of cosmological variations in physical constants are generally valid even in non-spherical, inhomogeneous spacetimes, supporting the use of local experiments to detect such variations.

Contribution

It extends previous spherical symmetry results to more realistic, non-spherical spacetimes using matched asymptotic expansions, confirming local detection of cosmological variations.

Findings

Local variations track cosmological changes in realistic spacetimes

Conditions for local detection are almost always satisfied

Quantified differences between local and cosmological variations

Abstract

We investigate the conditions under which cosmological variations in physical `constants' and scalar fields are detectable on the surface of local gravitationally-bound systems, such as planets, in non-spherically symmetric background spacetimes. The method of matched asymptotic expansions is used to deal with the large range of length scales that appear in the problem. We derive a sufficient condition for the local time variation of the scalar fields driving variations in 'constants' to track their large-scale cosmological variation and show that this is consistent with our earlier conjecture derived from the spherically symmetric problem. We perform our analysis with spacetime backgrounds that are of Szekeres-Szafron type. They are approximately Schwarzschild in some locality and free of gravitational waves everywhere. At large distances, we assume that the spacetime matches smoothly onto a Friedmann background universe. We conclude that, independent of the details of the scalar-field theory describing the varying `constant', the condition for its cosmological variations to be measured locally is almost always satisfied in physically realistic situations. The very small differences expected to be observed between different scales are quantified. This strengthens the proof given in our previous paper that local experiments see global variations by dropping the requirement of exact spherical symmetry. It provides a rigorous justification for using terrestrial experiments and solar system observations to constraint or detect any cosmological time variations in the traditional `constants' of Nature in the case where non-spherical inhomogeneities exist.