Spacetime, Spin and Gravity Probe B

TL;DR

This paper reviews spin-based experimental tests of General Relativity, highlighting Gravity Probe B's role in confirming key predictions and constraining alternative gravity theories, thus supporting current astrophysical and cosmological models.

Contribution

It provides a comprehensive overview of spin-based tests of gravity, emphasizing recent experimental results from Gravity Probe B and their implications for alternative theories.

Findings

Gravity Probe B confirmed geodetic precession and frame-dragging.

Experimental results constrain non-metric gravity theories.

Supports the validity of General Relativity in strong-field regimes.

Abstract

It is more important than ever to push experimental tests of gravitational theory to the limits of existing technology in both range and sensitivity. This brief review focuses on spin-based tests of General Relativity and their implications for alternative, mostly non-metric theories of gravity motivated by the challenge of unification with the Standard Model of particle physics. The successful detection of geodetic precession and frame-dragging by Gravity Probe B places new constraints on a number of these theories, and increases our confidence in the theoretical mechanisms underpinning current ideas in astrophysics and cosmology.