Testing Relativistic Effect of Propagation of Gravity by Very-Long Baseline Interferometry

TL;DR

This paper proposes a novel experimental test of general relativity by measuring the finite speed of gravity through VLBI observations of quasars during close encounters with Jupiter, detecting an excess time delay.

Contribution

It introduces a new method to directly measure the propagation speed of gravity using VLBI during planetary quasar alignments, expanding tests of general relativity.

Findings

Finite speed of gravity affects VLBI observations during planetary alignments.

Proposes a specific observational event in September 2002 for testing.

Detects an excess time delay beyond the standard Shapiro delay.

Abstract

It is shown that the finite speed of gravity affects very-long baseline interferometric observations of quasars during the time of their line-of-sight close angular encounter with Jupiter. The next such event will take place in 2002, September 8. The present Letter suggests a new experimental test of general relativity in which the effect of propagation of gravity can be directly measured by very-long baseline interferometry as an excess time delay in addition to the logarithmic Shapiro time delay (Shapiro, I. I., 1964, Phys. Rev. Lett., 13, 789).