In recent study, the invariance of the phase of plane waves among all inertial frames is challenged by a counter-example, that is, there is the negative frequency of plane waves in the case of“superluminal” motion of the medium, where the four-vector (k, ω/c) of plane waves is exceptionally not Lorentz-covariant. A new argument that the conventional invariance of the phase of plane waves should be replaced by the invariance of the phase difference of plane waves among all inertial frames is presented. Based on our argument, the explanation to the counter-example is worked out. The result shows that the four-vector of plane waves is still Lorentz-covariant.

Study on the invariance of the phase of plane wave

        原来的想法是无论写出任何文章，只要中文期刊能够发表，那就用中文发表。就当是爱国了，实际是英文太差。可事实上太难了！无法实现的。08年的一篇会议文章被一不入流的中文‘科技核心’主动录用，录用两年多了，版面费交了也两年多了，就是发不出来。理由是：找不到合适的审稿人，还要继续找。

       没办法，只有‘卖国求荣了’，把原本就学不会的英文搬出来试试。希望各位指教！