Any faster than light signal can create backward time effect by means of some frames seeing the signal go to the past of the origin. Is there any illustration or web site that illustrates this clearly? I'd like to know if the return path carrying the signal needs to travel faster than light or mere superluminal signalling is enough. For example. Supposed we sent a faster than light signal to pluto. Then it was sent back at similarly superluminal velocity. Would it reach the origin before it was sent out.. or do you have to carry the signal in a superluminal carrier like spaceship for this backward time effect to manifest at the origin?