Dynamics of Fundamental Constants in Cosmology
Summary
The dynamics of fundamental constants in cosmology concern the possibility that dimensionless parameters of nature—such as the fine-structure constant (α), the proton–electron mass ratio (μ) and the proton g-factor (g_p)—may vary over space and time. Such variations are predicted in many theoretical frameworks, including scalar-field models that couple to standard matter, string-inspired scenarios and grand unification theories. Observational tests span laboratory atomic clocks, quasar absorption lines, cosmic microwave background anisotropies and big bang nucleosynthesis. These probes address complementary regimes: local experiments constrain temporal drifts at the present epoch, while astrophysical measurements access variations over billions of years and across vast cosmic distances. A confirmed variation would signal new physics beyond general relativity and the standard model, potentially illuminating the nature of dark energy or the quantum structure of spacetime. Conversely, ever-tighter bounds reinforce the universality of physical laws and the validity of the equivalence principle. The field thus sits at the interface of high-energy theory, astrophysical observation and precision measurement, with implications for our understanding of gravitational coupling, particle masses and the fine-tuning of cosmological parameters.
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Dynamics of Fundamental Constants in Cosmology publication trend
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Technical terms
Fine-structure constant (α): A dimensionless measure of electromagnetic coupling strength.
Proton–electron mass ratio (μ): The ratio of proton to electron mass, sensitive to strong-interaction scale.
Proton g-factor (g_p): A dimensionless factor characterising the proton’s magnetic moment.
Cosmological redshift (z): The fractional increase in wavelength of light due to cosmic expansion.
Many-Multiplet method: A spectroscopic technique that compares multiple atomic transitions to detect variations in α.
Equivalence principle: A core tenet of general relativity stating that inertial and gravitational masses are identical.
References
- Constraints on the Fractional Changes of the Fundamental Constants at a Look-back Time of 2.5 Myr. The Astrophysical Journal Letters (2025).
- Constraints on the Spacetime Variation of the Fine-structure Constant Using DESI Emission-line Galaxies. The Astrophysical Journal (2024).
- Varying Constants, Gravitation and Cosmology. Living Reviews in Relativity (2011).
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