Reply to ``Comment on Model-dependence of Shapiro time delay and the `speed of gravity/speed of light' controversy''

TL;DR

This paper defends previous findings on the dependence of the Shapiro time delay on the speed of gravity versus light, clarifying that the earlier conclusions remain valid within a bimetric framework.

Contribution

It provides a detailed rebuttal to claims that the earlier model missed a dependence on the speed of gravity, reaffirming the original conclusions.

Findings

The analysis confirms no hidden dependence on the speed of gravity.

The original conclusions about the Shapiro delay are upheld.

The bimetric model analysis clarifies the observational dependencies.

Abstract

To determine whether the Shapiro time delay of light passing near a moving object depends on the ``speed of gravity'' or the ``speed of light,'' one must analyze observations in a bimetric framework in which these two speeds can be different. In a recent comment (gr-qc/0510048), Kopeikin has argued that such a computation -- described in gr-qc/0403060 -- missed a hidden dependence on the speed of gravity. By analyzing the observables in the relevant bimetric model, I show that this claim is incorrect, and that the conclusions of gr-qc/0403060 stand.