Testing Constancy of Speed of Photons

Special Relativity (SR) is the cornerstone for modern physics and for variety of applications. SR is based on two postulations, the principle of relativity and the principle of constancy of the propagation speed of light wave. However, up to now, the constancy of the propagation speed of light wave has not been experimentally confirmed yet. Recently we have shown that light propagate as particles even in “pure” wave experiments. In this article we propose a doable experiment to test the second postulation for photons as shown below. 

If the experiment shows a negative result, i.e., the constancy of the speed of light as photons holds, then we, the first time, confirm experimentally the second postulation of SR. If the experiment shows a positive result, i.e., the propagation speed of photons is not constant, then, the second postulate of SR is disproved. Either negative or positive results would be profoundly significant.