2004年6月，位于西非Oklo的美国Los Alamos实验室的核工业反应堆对实验数据做再分析后得出结论说，近20亿年内精细结构常数减小了4.5×10^-8。常数不常，意味着光速有很小的变化。这是最新的与狭义相对论不符的实验报告。另一方面，光子如有质量，Maxwell方程组将被Proca方程组所取代，而磁矢位（势）A将成为可观测量。而过去和现在都有许多方法测量光子的质量。

文章的主要目的是在Proca理论框架内研究电磁波波速，发现即使在自由空间（真空）条件下也会出现超光速传播；同时又对波导与Proca波的截止现象做了比较，给出了相应的结果。

In June 2004, re-analysis of Oklo (in Gabon, West Africa) LANL nuclear reactor data finds that, the Fine Structure Constant (a) has decreased by 4.5 parts in 10⁸ in last 2 billion years (Phys. Rev. D, Vol. 69，P. 121701), that translates into a very small increase in the speed of light. This is the experimental situation against the classical special relativity (SR) recently, but there are problems of interpretation. In other-wise, for a massive photon the Maxwell equations get replaced by the Proca equations. And then, the magnetic veotor potential A becomes observable. There are old methods and recent mearements about the rest mass of photon, so we believe that, in fact the photon is massive.

The main, linear extensions of Maxwell equations are the Proca equations (1936) and the Ohmara equations (1956). The purpose of this paper is to study the EM-wave velocity in the Proca's theory frame. And it is found that there is superluminal speed of the electro-magnetic waves which propagate in the free-space (vacuum). In the paper, a comparison is made between the cut-off phenomenon of waveguide and the Proca waves, the significant results is presented.