Does anyone have any favorite applications of the acceleration four-vector? More specifically, the WP article "four-acceleration," http://en.wikipedia.org/wiki/Four-acceleration (possibly written by former PF member CH), says, "Four-acceleration has applications in areas such as the annihilation of antiprotons, resonance of strange particles and radiation of an accelerated charge," with a reference to a book by Tsamparlis. The Tsamparlis is expensive, and I've only looked at it through Amazon's "look inside" keyhole. The acceleration vector is discussed in section 7.2. This section lists the same three applications as the WP article, but doesn't actually discuss any of them. I was able to find a discussion of the radiation application in section 13.16, but couldn't find any discussion of the first two, which seem explicitly quantum-mechanical. Anyone have any idea what the heck Tsamparlis had in mind there? It seems a little implausible to me that acceleration would be of any use in discussing a quantum-mechanical process, since Newton's laws hold in quantum mechanics only on the average.