Superluminal signal velocity, G. Nimtz, Ann. Phys (Leipzig) 7 (1988), 7-8, 618-624
Abstract. It recently has been demonstrated that signals conveyed by evanescent modes can travel faster than light. In this report some special features of signals are frequency band limited. Evanescent modes are characterized by extraordinary properties: Their energy is negative, they are not directly measurable, and he evanescent region is not causal since the modes traverse this region instantaneously. The study demonstrates the necessity of quantum mechanics in order to understand the superluminal velocity of classical evanescent modes.