The following is a paper by H. Aspden published in Physics Letters, v. 85A, pp. 411-414 (1981).


Abstract: Although gas lasers provide highly coherent light sources useful in interferometry experiments, their application to the measurement of light-speed anisotropy can produce inconclusive results unless reflection effects at mirror surfaces are taken fully into account. A recent experiment by Brillet and Hall is discussed and shown to indicate a local anisotropy due solely to Earth rotation.

Commentary: The author was here directing attention to the sensing the Earth's west-east speed, as opposed to rotation, that was evident in the Brillet and Hall experiment. Though quoted as a test for Einstein's theory, owing to the failure to sense motion through space at a cosmic speed, the sensing of actual speed, owing to linear motion relative to the inertial frame, invalidates the theory of relativity. The author later underlined the point made in this paper by the more extensive analysis presented in reference [1982e].