Do the fundamental constants change with time ?

TL;DR

This paper reviews methods for detecting potential changes in fundamental constants over time using spectral lines from distant galaxies, highlighting a new promising technique based on conjugate satellite OH lines.

Contribution

It introduces a novel method using conjugate satellite OH lines that reduces systematic uncertainties in testing the constancy of fundamental constants.

Findings

Conjugate satellite OH lines offer a promising approach for future measurements.

Current techniques have systematic limitations that the new method aims to overcome.

The review compares advantages and disadvantages of existing methods.

Abstract

Comparisons between the redshifts of spectral lines from cosmologically-distant galaxies can be used to probe temporal changes in low-energy fundamental constants like the fine structure constant and the proton-electron mass ratio. In this article, I review the results from, and the advantages and disadvantages of, the best techniques using this approach, before focussing on a new method, based on conjugate satellite OH lines, that appears to be less affected by systematic effects and hence holds much promise for the future.