Einstein tried to explain MM EXPERIMENT null result by postulating speed of light constan by any observer on any reference frame. So if you approach a light source or move away from light source, you can not apply Galilean Transform. Einstein developed relativity by applying Lorentz Transform instead of Galilean Transform. He never explained what is all pervading EM WAVES which must have been emitted photon by photon from source with different time tag as presnt all around to an observer . So time has been confused here itself. Now if you give photon by photon a time tag and can apply Galilean while approaching or moving away from the source. He never explained that situation also but postulating speed of light constant served his purpose to explain MM results and developing relativity theory with a bizzare concet of TIME DILATION.