Information has not been observed to travel faster than light. What I mean by “FTL travel allows the traveler to go back in time” is, if one were to abuse the equations to get a traveler that is moving faster than light, some times would also end up looking negative.

But these are nonsense quantities that come about from abusing the equations, I mention it not because I think it is a practical concern but to highlight that we can’t just say “assuming FTL” without also being charged with ancillary crimes against the laws of physics!