Comment on “Measurements of Newton’s gravitational constant and the length of day” by Anderson J. D. et al

Introduction. – In [1] the authors claim to observe a periodic signal in measurements of Newton’s gravitational constant, G. Specifically they find a 5.9-year-period signal that is strongly correlated with variations in the observed length of day [2]. They do not suggest that G actually varies on these time scales, but rather that there could be some systematic effect on the measurement process that is correlated with the mechanism that leads to the variation in the length of day. Here I present a reanalysis of the data used in [1] using Bayesian model selection to test the hypothesis that the data contains a periodic signal compared to other potential models. In light of updated information on the times of the various G measurements given in [3] I also reanalyse this new dataset with the same method. In both datasets I have found that a model for the variations in G that only contains an additional Gaussian noise term is hugely favoured, by factors of e30, over models containing a sinusoid term1.