Phase and frequency shift in a Michelson interferometer

Traditionally, the outcome of Michelson's interference experiment has been interpreted as evidence against the existence of a luminiferous medium called "ether." Einstein, however, emphasized in 1920 that an ether must exist in spite of Michelson's null result. In this paper, it is shown that a medium theory-be it for light or for sound-actually predicts the observed null result. Michelson expected a gradual fringe shift when his apparatus was turned in the "ether wind." Such a phase change would, however, require a temporary frequency change in one of the interferometer arms. Since wind does not alter the frequency in the interferometer, a phase shift cannot occur either. (C) 2014 Physics Essays Publication.