On the Speed of Gravity and Relativistic v/c Corrections to the Shapiro Time Delay

TL;DR

This paper clarifies the measurement of gravity's speed using Jupiter-quasar observations, confirming that relativistic v/c effects are only observable if gravity propagates at a finite speed, contrary to some claims.

Contribution

The authors present a Lorentz-invariant analysis of the Jovian deflection experiment, refuting claims that v/c effects are unmeasurable and showing they vanish only if gravity's speed is infinite.

Findings

v/c effects are observed in the experiment

v/c effects vanish if gravity's speed is infinite

Lorentz-invariant formulation confirms the measurement validity

Abstract

Recent papers by Samuel declared that the linearized post-Newtonian v/c effects are too small to have been measured in the recent experiment involving Jupiter and quasar J0842+1845 that was used to measure the ultimate speed of gravity defined as a fundamental constant entering in front of each time derivative of the metric tensor in the Einstein gravity field equations. We describe our Lorentz-invariant formulation of the Jovian deflection experiment and confirm that v/c effects are do observed, as contrasted to the erroneous claim by Samuel, and that they vanish if and only if the speed of gravity is infinite.