Time-Dependent Gravitational Coupling and Torsion

Abstract

In the context of Einstein-Cartan-Sciama-Kibble theory, modified to include a time-dependent gravitational coupling $G(t)$, torsion is shown to be proportional to the variation $\frac{\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{G}}{G}$. The magnitude of this effect based on recent experimental evidence is substantially greater than the usual spin-dependent torsion effects predicted by standard Einstein-Cartan-Sciama-Kibble theory. It is suggested that the detection of a time-varying $G$ could provide evidence for the existence of torsion.