If gravity propagated between the Sun and the Earth at the same speed as visible light, the Earth would double the distance from the Sun in 1200 years, which obviously isn’t happening. Many other notable physicists besides Newton and Lorentz also concluded that orbital calculations must be made using an infinite speed of gravity. Sir Arthur Stanley Eddington’s orbital calculations rely on gravity having an infinite speed, and Pierre-Simon Laplace calculated gravity to have a speed of at least 10^8 times the speed of light.
Van Flandern goes on to discuss GPS clocks, which are often cited as being proof positive of Einstein’s relativity. It may surprise you, but the GPS system doesn’t actually use Einstein’s field equations. In fact, this paper by the U.S. Naval Observatory tells us that, while incorporating Einstein’s equations into the system may slightly improve accuracy, the system itself doesn’t rely on them at all. To quote the opening line of the paper, “The Operational Control System (OCS) of the Global Positioning System (GPS) does not include the rigorous transformations between coordinate systems that Einstein’s general theory of relativity would seem to require.”
Van Flandern explains why this is so:
Finally, the Global Positioning System (GPS) showed the remarkable fact that all atomic clocks on board orbiting satellites moving at high speeds in different directions could be simultaneously and continuously synchronized with each other and with all ground clocks. No “relativity of simultaneity” corrections, as required by SR, were needed. This too seemed initially to falsify SR. But on further inspection, continually changing synchronization corrections for each clock exist such that the predictions of SR are fulfilled for any local co-moving frame. To avoid the embarrassment of that complexity, GPS analysis is now done exclusively in the Earth-centered inertial frame (the local gravity field). And the pre-launch adjustment of clock rates to compensate for relativistic effects then hides the fact that all orbiting satellite clocks would be seen to tick slower than ground clocks if not rate-compensated for their orbital motion, and that no reciprocity would exist when satellites view ground clocks.
Van Flandern also discusses the famous Michelson-Morely experiment, the Michelson-Gale experiment, and the Sagnac experiment, which are often cited as discrediting Lorentz’s version of relativity. The truth of the matter is that Lorentz’s version of relativity can easily account for the observations if one simply assumes a local gravity field with preferred frame for local observers, rather than a universal gravity field. Further, at the time, the wave nature of matter has not yet been discovered by Louis de Brogli
