Williams et al. Reply (to the Comment by Dumin on "Progress in Lunar Laser Ranging Tests of Relativistic Gravity")

TL;DR

This paper discusses constraints on the variation of the gravitational constant G over time, using lunar laser ranging data to limit possible solar system expansion and test relativistic gravity theories.

Contribution

It provides updated empirical limits on the temporal variation of G and the resulting solar system expansion rate, refining previous constraints with recent lunar laser ranging data.

Findings

Limits on ot G/G are q to  b1 9 b5 10^{-13} yr^{-1}

Solar system expansion rate constrained to ot a/a = q to  b1 9 imes 10^{-13} yr^{-1}

Results support the stability of G and the validity of general relativity at solar system scales.

Abstract

A decreasing gravitational constant, G, coupled with angular momentum conservation is expected to increrase a planetary semimajor axis, a, as \dot a/a=-\dot G/G. Analysis of lunar laser ranging data strongly limits such temporal variations and constrains a local (~1 AU) scale expansion of the solar system as \dot a/a=-\dot G/G =-(4\pm9)\times10^{-13} yr^{-1}, including that due to cosmological effects.