The speed of gravity has not been measured from time delays
Abstract
The recent passage of Jupiter by the quasar QSO J0842+1835 at a separation of 3.7 arcminutes on September 8, 2002, combined with recent advances in interferometric radio timing, has allowed for the first measurement of higherorder postNewtonian terms in the Shapiro time delay which depend linearly on the velocity of the gravitating body. Claims have been made that these measurements also allow for the measurement of the propagation speed of the gravitational force. This conclusion disagrees with recent calculations done in the parameterized postNewtonian (PPN) model, which find no dependence of the velocitydependent terms in the time delay on the speed of gravity to the stated order. Here, to test out these claims and counterclaims, we calculate the time delay in the limit of an instantaneous gravitational force, and find that the velocitydependent terms are in complete agreement with previous PPN calculations, with no dependence on the speed of gravity. We conclude that the speed of gravity cannot be determined by measuring these terms in the Shapiro time delay, and suggest a reason why other groups mistakenly came to the opposite conclusion.
 Publication:

arXiv eprints
 Pub Date:
 March 2003
 DOI:
 10.48550/arXiv.astroph/0303346
 arXiv:
 arXiv:astroph/0303346
 Bibcode:
 2003astro.ph..3346F
 Keywords:

 Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 5 pages, no figures, RevTeX, submitted to ApJ Lett