Let's talk about varying G

Abstract

It is possible that fundamental constants may not be constant at all. There is a generally accepted view that one can only talk about variations of dimensionless quantities, such as the fine structure constant ${\alpha }_{\mathrm{e}}\equiv e^2/4\pi {\epsilon }_0\hslash c$. However, constraints on the strength of gravity tend to focus on G itself, which is problematic. We stress that G needs to be multiplied by the square of a mass, and hence, for example, one should be constraining ${\alpha }_{\mathrm{g}}\equiv G{m}_{\mathrm{p}}^2/\hslash c$, where $m_{\mathrm{p}}$ is the proton mass. Failure to focus on such dimensionless quantities makes it difficult to interpret the physical dependence of constraints on the variation of G in many published studies. A thought experiment involving talking to observers in another universe about the values of physical constants may be useful for distinguishing what is genuinely measurable from what is merely part of our particular system of units.

6 pages, Gravity Research Foundation essay

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Cited by in corpus (6)

• Matter Non-conservation in the Universe and Dynamical Dark Energy
• Tilted Physics: A Cosmologically Dipole-Modulated Sky
• Generalized Entropy Implies Varying-G: Horizon Area Dependent Field Equations and Black Hole-Cosmology Coupling
• Dimensionless cosmology
• One possible mechanism for massive neutron star supported by soft EOS
• JWST observations constrain the time evolution of fine structure constants and dark energy - electromagnetic coupling