Abstract

This paper revisits the problem stated by Hayden and Whitney many years ago: ?If Michelson-Gale, why not Michelson-Morley?? With that question in mind a brief review is first made of the most important experiments in the history of Physics designed to detect the motion of a light source with velocity v. The anisotropic terms (c+v) and (c-v) could reveal, or not, the motion of the source within the frame of the moving source. Some of these experiments are: Sagnac (1913), Michelson-Gale (1925), Bradley (1728) and gyro-lasers (1980), all of which showed positive (c ? v) effects. On the negative side are: Michelson-Morley (1887) and its many repetitions, and terrestrial aberration (Muller 1992), which showed no (c ? v) effects in agreement with the Principle of Relativity. The experiments are compared in terms of the velocities involved, the centripetal accelerations, if any, the light times of flight, and most importantly, the geometry of the optical paths in each case.

In the second part of this paper an analysis is made of the experiment performed by five Brazilian scientists (January 2007) whereby they claim to have detected the motion of the Earth towards Leo, by means of a laser diffraction experiment. An attempt to reproduce the experiment in Miami, Florida, in our laboratory, has shown various technical difficulties and has yielded no conclusive evidence as of this writing. A final hypothesis is suggested concerning the reason why the diffraction experiment could yield positive (c ? v) effects in contrast with the null results analyzed in the first part and even with the positive results of Sagnac, Michelson-Gale, gyro-lasers, etc.