Polarization rotation, reference frames and Mach's principle

TL;DR

This paper investigates how light polarization rotates in gravitational fields, distinguishing Machian effects from geometric contributions, and suggests polarization rotation could serve as a future gravity probe.

Contribution

The authors construct local reference frames in stationary space-times to isolate Machian effects and analyze polarization rotation, highlighting its potential as a gravity measurement tool.

Findings

Polarization rotation is more significant than previously thought.

The phase is gauge-independent along closed trajectories.

The geometric term can dominate the polarization phase.

Abstract

Polarization of light rotates in a gravitational field. The accrued phase is operationally meaningful only with respect to a local polarization basis. In stationary space-times, we construct local reference frames that allow us to isolate the Machian gravimagnetic effect from the geodetic (mass) contribution to the rotation. The Machian effect is supplemented by the geometric term that arises from the choice of standard polarizations. The phase accrued along a close trajectory is gauge-independent and is zero in the Schwarzschild space-time. The geometric term may give a dominant contribution to the phase. We calculate polarization rotation for several trajectories and find it to be more significant than is usually believed, pointing to its possible role as a future gravity probe.