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Comparing Spinning Mossbauer, GPS, and VLBI Experiments

Ronald R. Hatch
Year: 1994 Pages: 8
Spinning Mossbauer experiments, with gamma ray source and detector on a spinning disk, are frequently cited as providing strong evidence in support of the special theory. However, as Hayden has shown, the claims are generally based upon two separate phenomena. Ruderfer suggested that one could detect the variation of the transit time across either the radius or diameter of the spinning disk if an ether wind were present. Turner and Hill looked for a change in the frequency of the gamma rays as a function of the source velocity. If an ether wind were present, then a modulation of the frequency with the spin would presumably appear. Ruderfer, in an erratum, pointed out that the two effects would cancel and render the experiment incapable of detecting an ether wind. In spite of this erratum, the claims are repeatedly found in the literature that the spinning Mossbauer experiments support the special theory. They do not. They are simply moot on the subject.

The Global Positioning System (GPS) constitutes a large scale near-equivalent to the spinning Mossbauer experiments. The transit time between the satellite and ground-based receivers is routinely measured. In addition, the atomic clocks on the satellite are carefully monitored; and high precision corrections are provided as part of the information transmitted from the satellites. Because the satellites and the receivers rotate at different rates (unlike the Mossbauer experiments), a correction for the motion of the receiver during the transit time is required. This correction is generally referred to as a Sagnac correction, since it adjusts for an anisotropy of the speed of light as far as the receiver is concerned. Why is there no requirement for a Sagnac correction due to the earth\'s orbital motion? Like the transit time in the spinning Mossbauer experiments, any such effect would be completely canceled by the orbital velocity.

The Very Long Baseline Interferometry (VLBI) experiments extend the phonomena of interest to aberration effects as well as the Sagnac effect.