The status of varying constants: a review of the physics, searches and implications

2017/08/14 by C. J. A. P. Martins, C J A P Martins · 1 voice · 1 citation
Physics and Astronomy · #Consistency (knowledge bases) #Cosmology #Cosmology and Gravitation Theories #Physics beyond the Standard Model #Preference #Radioactive Decay and Measurement Techniques #Range (aeronautics) #Relativity and Gravitational Theory #Stability (learning theory) #Statistical hypothesis testing #Task (project management) #astro-ph.CO #gr-qc #hep-ph #hep-th

paper · pdf · doi:10.1088/1361-6633/aa860e

Invited review for Reports on Progress in Physics (49 pages, 6 figures, 11 tables; submitted 24 January 2017, accepted 14 August 2017)

openalex publication_date 2017/08/14 · openalex created_date 2017/08/31 · arxiv created 2017/09/09 · arxiv published 2017/09/09 · arxiv updated 2017/09/12 · openalex updated_date 2026/08/05

Abstract

The observational evidence for the recent acceleration of the universe demonstrates that canonical theories of cosmology and particle physics are incomplete-if not incorrect-and that new physics is out there, waiting to be discovered. A key task for the next generation of laboratory and astrophysical facilities is to search for, identify and ultimately characterize this new physics. Here we highlight recent developments in tests of the stability of nature's fundamental couplings, which provide a direct handle on new physics: a detection of variations will be revolutionary, but even improved null results provide competitive constraints on a range of cosmological and particle physics paradigms. A joint analysis of all currently available data shows a preference for variations of α and μ at about the two-sigma level, but inconsistencies between different sub-sets (likely due to hidden systematics) suggest that these statistical preferences need to be taken with caution. On the other hand, these measurements strongly constrain Weak Equivalence Principle violations. Plans and forecasts for forthcoming studies with facilities such as ALMA, ESPRESSO and the ELT, which should clarify these issues, are also discussed, and synergies with other probes are briefly highlighted. The goal is to show how a new generation of precision consistency tests of the standard paradigm will soon become possible.

Citations

• Big Bang Nucleosynthesis: 2015
• First detection of CO in a high-redshift DLA
• Measurements of Ω and Λ from 42 High‐Redshift Supernovae
• Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC
• Dependence of nuclear magnetic moments on quark masses and limits on temporal variation of fundamental constants from atomic clock experiments
• Oklo reactors and implications for nuclear science
• Strong Limit on a Variable Proton-to-Electron Mass Ratio from Molecules in the Distant Universe
• Phenomenology of the equivalence principle with light scalars
• Frequency Ratio of Al+and Hg+Single-Ion Optical Clocks; Metrology at the 17th Decimal Place
• Nucleosynthesis and the time dependence of fundamental couplings
• Observational Probes of Cosmic Acceleration
• Constraints on the CMB temperature redshift dependence from SZ and distance measurements
• Quintessence and the Rest of the World
• The cosmological constant and dark energy
• Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant
• Varying constants, Gravitation and Cosmology
• Accelerating Universes with Scaling Dark Matter
• Particle Physics Models of Inflation and the Cosmological Density Perturbation
• Cosmic dynamics in the era of Extremely Large Telescopes
• Trialogue on the number of fundamental constants
• A test of general relativity using radio links with the Cassini spacecraft
• Quintessence in a quandary: Prior dependence in dark energy models
• Time variability of α from realistic models of Oklo reactors
• Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC
• Fundamental constants and high‐resolution spectroscopy
• Rolling Tachyon
• The Confrontation between General Relativity and Experiment
• Planck 2015 results. XIII. Cosmological parameters

Cited by

• Search for Variations of Fundamental Constants

Discussions

• There are many observational limits on variations in the electron-to-proton mass ratio ( $\mu=m_e/m_p$ ) and the fine structure constant ( $\alpha\propto e^2)$ over cosmological times and distances. ( [stackexchange, 2 points]

Related

• Varying fundamental constants and dark energy in the ESPRESSO era
• Fundamental constants: from measurement to the universe, a window on gravitation and cosmology
• Testing the variation of fundamental constants by astrophysical methods: overview and prospects
• Recent variations of fundamental parameters and their implications for gravitation
• Observational strategies for varying constants with ESPRESSO and ELT-HIRES