Well, we each have our own personal time based on where we are. It is theoretically possible to take off in a spaceship away from Earth and return before you left. This is known as The Hard-To-Understand-Crazy Theory.
Well that's because time traveling forward in time is EASY. You just sit and wait for it to happen.
And traveling backwards in time is theoretically possible inside black holes, except the openings would be too small to put anything through, and it wouldn't matter because you'd be trapped in a black hole. And then there's wormholes, which I know nothing about, but I feel like mentioning them, so I will. "Wormholes".
I went to college with Ron Rege Jr. We were in the same comic anthologies. I don't think I ever met him.
and if time travel were possible, someone from the future would have already traveled back in time to the present to tell us how time travel is possible, so therefore, it is not possible. So you totally missed the show dude.