Start with a Black Hole ...

The physical possibility of time traveL is something of a catch-22. Any object that's surrounded by the twisted space-time that time travel requires must by its very nature be fantastically perilous, a maelstrom that would inevitably tear apart the foolhardy traveler. So physicists have labored to create a theoretically acceptable time machine that's free from nasty side effects like certain death. Their starting point: black holes.