Okay, time travel is so purely theoretical as to almost be junk physics, but bear with me. A person sent back in time would in all likelihood experience a very different future than the one from which he left, and not just because small changes might have unforseeable consequences. Quantum mechanics rely heavily on probability, so if the universe somehow reversed and reinitated any event, it could well turn out differently. And since any future event will be contingent on previous events, it's obvious how quickly things would take a different direction even concering one single thread of quantum interaction. That's not even to mention that there are countless, <i>coooooountless</i> (incomprehensively huge, even within your own body) numbers of quantum events and collisions and adjustments every second, all of which add up to the physical universe.

So i wouldn't go back in time, i don't think.