# Theoretical Time Travel

1. Dec 20, 2015

### novella

I am writing a novel about time travel and don't quite understand the theoretical science behind it.
If I understand correctly, Einstein's General Relativity theory opened up the door for the possibility of time travel even though he dismissed the idea as impractical. Einstein proved that time and space were linked as one and called this the Space Time Continum. And this Space Time Continum is curved not straight allowing for the possibility of a closed loop being created and being referred to as a CTC or a Closed Timelike Curve.
What I would like explained is how theoretical time travel is accomplished along this CTC. Does the time traveler have to be traveling in space and at a certain speed along the CTC. Is it by pure chance that he even finds the CTC to allow for his time travel. Would he have to be traveling at the speed of light or close to this maximum universal speed. Does he have to enter a worm hole that connects two distant points along the CTC or could he just fly along the CTC and eventually lap his own lifeline winding up in his past.
If you could explain this in the simplest terms possible I would greatly appreciate it.

2. Dec 20, 2015

### guywithdoubts

Travelling to the past would violate causality, which I think to have understood to prohibit it quite emphatically.

3. Dec 20, 2015

### novella

I understand the objections like causality and things like The Grandfather Paradox but I know there are theoretical pysicists that have circumvented these prohibitions to time travel. Putting them aside for a moment, explain what I have asked: the mechanics of just getting there.

4. Dec 20, 2015

### bcrowell

Staff Emeritus
CTCs exist in many different forms, in many different types of spacetimes. In some spacetimes, such as the Godel metric, they exist throughout the universe. In others, such as wormhole spacetimes, they are localized, and you have to pass through the wormhole.

No, not in the examples above. Note that you can't even define speed in relativity unless you specify what it's relative to.

You might want to read Black Holes and Time Warps by Kip Thorne.

I think that's putting it much too strongly.

5. Dec 20, 2015

### Staff: Mentor

Welcome Novella. we have special rules for the sci-fi writing forum. your post has been moved here because it is not allowed allowed in the science forum.