Direct First-Order Experiment on the Propagation of Light from a Moving Source

Abstract

A direct experiment of first order in ν/c on the second Einstein postulate that the speed of light is independent of the uniform motion of its source has been performed in the laboratory. A qualitative result is obtained which does not agree with expectation based on the Einstein assumption. The result does accord qualitatively with expectation based on a description in which the relative speed of light is dependent on the uniform motion of the source.