Fine structure constant measurements in quasar absorption systems

TL;DR

This paper discusses using high-resolution quasar spectroscopy to detect potential variations in the fine structure constant across the universe, which could challenge fundamental physics principles.

Contribution

It reports on a large sample of measurements indicating possible spatial variation in the fine structure constant and highlights new methods to eliminate systematic errors.

Findings

Hints of a spatial dipole in the fine structure constant

Systematic effects may influence current measurements

New instrumentation and analysis methods aim to improve accuracy

Abstract

Detecting any evolution of dimensionless in the ratios of physical quantities, such as the fine structure constant, would prove that the Weak Equivalence Principle is violated and lead to a paradigm shift in physics. High resolution spectroscopy of quasar absorption systems can be used to test cosmological variations in time and/or in space. A sample of 300 measurements using data from 8m class optical telescopes provides hints that such variations are indeed present in a form of a spatial dipole across the sky, although systematic effects could dominate. Two recent developments, one in instrumentation and the other in analysis methods, promise to produce a new sample of measurements free from all known systematic effects to test the tentative dipole.