One day......we're going to observe the non-observable universe, and discover that it's exactly like this universe, except it"s last week. And then we'll do it again in a different direction, and it'll be next week. And we'll do it again, and again, and again, and again, and eventually figure out that everything we do, ever have done, or ever will do, only applies to THIS observable universe. And that we're one of an uncountable number of universes. Each a slightly different time than ours.

And no, it's not time travel. If you go to another universe, and kill Tom, then come back here, Tom is still alive. If you go back to that universe, Tom is still dead and you get arrested.