Cosmological Evolution of Fundamental Constants: From Theory to Experiment

TL;DR

This paper explores the theoretical basis and experimental evidence for the cosmological evolution of fundamental constants, highlighting implications for grand unified theories and the potential for low-energy measurements to test these ideas.

Contribution

It provides a comprehensive overview of how fundamental constants may vary over cosmological timescales, integrating theoretical mechanisms with current experimental constraints.

Findings

Cosmological evolution of constants is theoretically natural.

Gauge coupling unification could vary with time.

Precision measurements can test for time variation.

Abstract

In this paper we discuss a possible cosmological time evolution of fundamental constants from the theoretical and experimental point of views. On the theoretical side, we explain that such a cosmological time evolution is actually something very natural which can be described by mechanisms similar to those used to explain cosmic inflation. We then discuss implications for grand unified theories, showing that the unification condition of the gauge coupling could evolve with cosmological time. Measurements of the electron-to-proton mass ratio can test grand unified theories using low energy data. Following the theoretical discussion, we review the current status of precision measurements of fundamental constants and their potential cosmological time dependence.