A new test of conservation laws and Lorentz invariance in relativistic gravity

TL;DR

This paper presents a highly precise test of Lorentz invariance and conservation laws in relativistic gravity using binary pulsar systems, significantly improving previous constraints on deviations from general relativity.

Contribution

It introduces a new, more stringent limit on the PPN parameter alpha_3, indicating no detectable violation of conservation laws or preferred frames in relativistic gravity.

Findings

Alpha_3 < 2.2 x 10^-20 (90% CL)

Pulsar tests are among the most precise null experiments in physics

No evidence of Lorentz invariance violation in relativistic gravity

Abstract

General relativity predicts that energy and momentum conservation laws hold and that preferred frames do not exist. The parametrised post-Newtonian formalism (PPN) phenomenologically quantifies possible deviations from general relativity. The PPN parameter alpha_3 (which identically vanishes in general relativity) plays a dual role in that it is associated both with a violation of the momentum conservation law, and with the existence of a preferred frame. By considering the effects of alpha_3 neq 0 in certain binary pulsar systems, it is shown that alpha_3 < 2.2 x 10^-20 (90% CL). This limit improves on previous results by several orders of magnitude, and shows that pulsar tests of alpha_3 rank (together with Hughes-Drever-type tests of local Lorentz invariance) among the most precise null experiments of physics.