SUPERLUMINAL SIGNALS - CAUSAL LOOP PARADOXES REVISITED

Recent results demonstrating superluminal group velocities and tachyon ic dispersion relations reopen the question of superluminal signals an d causal loop paradoxes. The sense in which superluminal signals are p ermitted is explained in terms of pulse reshaping, and the self-consis tent behavior which prevents causal loop paradoxes is illustrated by a n explicit example. (C) 1998 Published by Elsevier Science B.V.