It is easier than that. All you need to do is wrinkle time with a singularity. The wrinkled time itself automatically creates a copy of your current universe. Step into the copy and you can go forward or backward in the time of this copied universe. The second singularity keeps you from being crushed into the first singularity. Now I make this sound simple, but atomic energy is needed to run things. That is the reason for the civil defense detection equipment.
This makes sense when you say it, but I can never explain it myself.
