Whether Einstein's 1905 light postulate is true or false depends on whether light pulses bunch up in front of the moving source or not:

http://www.einstein-online.info/imag...ler_static.gif

http://www.einstein-online.info/imag...ource_blue.gif

Light pulses don't bunch up - bunching up obviously violates the principle of relativity. Rather, the speed of light VARIES with the speed of the source, as posited by Newton's emission theory:

"Emission theory, also called emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887. [...] The name most often associated with emission theory is Isaac Newton. In his corpuscular theory Newton visualized light "corpuscles" being thrown off from hot bodies at a nominal speed of c with respect to the emitting object, and obeying the usual laws of Newtonian mechanics, and we then expect light to be moving towards us with a speed that is offset by the speed of the distant emitter (c ± v)." https://en.wikipedia.org/wiki/Emission_theory

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