Tests of gravitational symmetries with radio pulsars

TL;DR

This paper reviews experimental tests of fundamental gravitational symmetries, emphasizing pulsar astronomy results that support general relativity and the strong equivalence principle across various scales.

Contribution

It provides a comprehensive overview of recent experimental tests of gravitational symmetries, highlighting pulsar-based tests and their implications for general relativity.

Findings

Tests strongly support the strong equivalence principle

Pulsar experiments confirm predictions of general relativity

High-precision measurements show no violations of gravitational symmetries

Abstract

Symmetries play important roles in modern theories of physical laws. In this paper, we review several experimental tests of important symmetries associated with the gravitational interaction, including the universality of free fall for self-gravitating bodies, time-shift symmetry in the gravitational constant, local position invariance and local Lorentz invariance of gravity, and spacetime translational symmetries. Recent experimental explorations for post-Newtonian gravity are discussed, of which, those from pulsar astronomy are highlighted. All of these tests, of very different aspects of gravity theories, at very different length scales, favor to very high precision the predictions of the strong equivalence principle (SEP) and, in particular, general relativity which embodies SEP completely. As the founding principles of gravity, these symmetries are motivated to be promoted to even stricter tests in future.