Kassir, Radwan M.
August 18, 2020
Relativity principle, Speed of light postulate
Relativists claim that Einstein’s constancy of the speed of light postulate is a consequence of the principle of relativity. Perhaps they consider this as the strongest argument in defending Special Relativity. They maintain that their assertion is supported by the Michelson-Morley experiment, in which the Earth motion couldn’t be detected—in accordance with the principle of relativity— on the basis that the speed of light is relative, defying the foreseen variation of the speed of a light ray with its propagation direction in relation to the Earth motion direction. Since the relativity principle is well accepted among physicists, relativists promote the idea that the constancy of the speed of light postulate follows from the relativity principle, thus making the former as legitimate as the latter. In this paper, the aforementioned claim is shown to be flawed, and has no valid justification; even more, the speed of light postulate is actually revealed to violate the principle of relativity.