In 2005, the "World Year of Physics," it may be interesting to guess how Albert Einstein would feel to hear about the controversy over the speed of gravity in relation to his theory of gravity. First of all, measuring the speed of gravity is a challenging subject in physics and has attracted a lot of interest especially since Kopeikin published his paper about the related VLBI experiment,1 though no papers by anyone else have yet supported his claim, as I criticized in Ref. 2 and S. Samuel recently reviewed in Ref. 3. We should apply Einstein's famous saying, "insanity is doing the same thing over and over again and expecting different results," and figure out what to do differently that will bring about success. Most readers who are not experts in this field do not have time to thoroughly read the rebuttal by S. Kopeikin.4 The most important point in that paper, which first appeared in Ref. 1, is that the static Shapiro delay in Eq. (14) is the inverse of ⊖ whereas its correction in Eq. (15) is ⊖-2, where ⊖ is the angle at the Earth (observer) between the Jupiter (deflector) and quasar (source). We are unsure of this because the correction would exceed the leading term if ⊖ nearly vanished, though the effect of the gravity propagation on the light ray must become smaller in the ⊖ → 0 limit since the distance between the deflector and the light trajectory is shorter. Therefore, I would suggest that once again, there must be something misleading in Kopeikin's latest paper.4 © World Scientific Publishing Company.
