You probably know this, but I think it goes back to Einstein. Time slows for an object the faster it moves. It's a theory that if you could go fast enough, time would actually move backwards.

I really don't think events would go backwards. I doubt it. It could be awkward to have a chicken un-lay an egg, for example. I'm hoping I could back up in age 20 years or so. Thing is, everything NOT moving at that speed would go on as normal, so if I was half as old, everybody else would be twice as old.

Of course, this means those Star Trek episodes with them doing a sling-shot around a star are bogus because they couldn't have slammed the whole universe into reverse.