It's a commonly made misinterpretation of the equations of relativity that one would go backward in time when travelling faster than light. In fact, the equations say nothing of the sort. If we input a velocity faster than light, the time elapsed is given by an imaginary number (not a negative one). That is, a solution that has no real physical interpretation. This is why FTL travel is (usually) forbidden. The current FTL studies mentioned on other threads involve quantum probabilities, and thus avoid having weird time effects, What physicists are worried about is having to mess around with the 'light cone' theories of causality, not backward time travel.