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Varying G and Other Constants

John D. Barrow
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Abstract

We review recent progress in the study of varying constants and attempts to explain the observed values of the fundamental physical constants. We describe the variation of $G$ in Newtonian and relativistic scalar-tensor gravity theories. We highlight the behaviour of the isotropic Friedmann solutions and consider some striking features of primordial black hole formation and evaporation if $G$ varies. We discuss attempts to explain the values of the constants and show how we can incorporate the simultaneou s variations of several 'constants' exactly by using higher-dimensional unified theories. Finally, we describe some new observational limits on possible space or time variations of the fine structure constant.

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John D. Barrow. 1997-11-27. Varying G and Other Constants. https://arxiv.org/abs/gr-qc/9711084

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