henry (08/06/82)
The problem with any FTL transmission of information is that when one has cause and effect connected by such transmission, from a frame of reference moving at a suitable speed in a suitable direction the cause and the effect appear to be reversed. Instantaneous transmission is not required. Any form of FTL information transmission requires either substantial revision of Special Relativity (which, alas, is on much firmer ground than the somewhat-dubious General Relativity) or else a renunciation of the principle that all observers should see cause and effect working the same way. Perhaps this principle can be abandoned, but it is not easy to construct a replacement. If different observers can see different series of events when watching the same phenomena, it's hard to arrange things so that any specific observer is guaranteed to see a self-consistent series of events. This has been attempted, by the tachyon theorists, but the results are somewhat unsatisfying so far.