What if there are superluminal signals?

Abstract:

Recent experiments with microwaves indicate the existence of signals travelling faster than the vacuum velocity of light. At first glance these signals lead to paradoxical situations which seem to be in conflict with special relativity. We show that the arguments which lead to this contradiction presuppose that superluminal signals are not generally available and that the space-time geometry must be established by means of light rays. Hence we argue that superluminal signals will not necessarily invalidate special relativity.