My take on time travel is that it is impossible. Here is my reasoning: the universe is constantly evolving, be it's wave function or thermodynamically. To move backwards in time, you have to reverse the state of the universe to that of your choosing. To do that, you have to do work. Think about the amount of energy necessary to move all particles of the universe 1 second to the past. Besides, you don't know the state of the universe, not because you don't have enough information, but on principle it is impossible to know (quantum mechanics).