# Physics Behind Time Loops In Movies?

1. Jun 21, 2017

### TheQuestionGuy14

I was just wondering if there is any physics behind the time loops in the movies Groundhog Day or Edge of Tomorrow.

2. Jun 21, 2017

### Staff: Mentor

The short answer is no. There's no mechanism to explain how the time loop works. Its just used as an interesting story device.

When talking about time loops, the closest movie might be Interstellar where the astronauts experience time dilation while working near a black hole.

3. Jun 21, 2017

### DHF

I believe the only known mechanism to alter Time, is gravity. so if you had a situation where time was so distorted that it bent back on itself, then you would also be in the presence of a gravity well so enormous that time looping would be the least of your worries.

4. Jun 21, 2017

### phinds

Gravity cannot cause time looping. As Jedishrfu already pointed out, it can cause differential aging, that's all.

5. Jun 21, 2017

### Staff: Mentor

6. Jun 21, 2017

### phinds

To be completely clear, gravity does NOT "alter time", it simply provides an alternate path through space-time which results in differential aging. Clocks always tick locally at one second per second.

7. Jun 21, 2017

### DHF

Thank you for the clarification.

8. Jun 21, 2017

### Staff: Mentor

The reason so many people (me included) love sci-fi stories with time loops is the imagination. It is fun! A modern way to tell fairy tales. Nobody of today is really afraid of mean wolves, but the implications of the grandfather paradox are funny. And once you have a contradiction in your system, you can justify everything, which gets the story teller even more freedoms and us watchers or readers more fun.

9. Jun 21, 2017

### Staff: Mentor

10. Jun 21, 2017

### Staff: Mentor

11. Jun 21, 2017

### George Jones

Staff Emeritus
Yes, there is. At what level do you want an answer?

12. Jun 21, 2017

### TheQuestionGuy14

What do you mean by level? Also, are you talking about Closed Timelike Curves? I've heard of those recently.

13. Jun 21, 2017

### George Jones

Staff Emeritus
Yes, I mean closed timelike curves.

By "level", I mean "What background in physics and math do you have?" It is okay if you don't have any background in physics and math, but I will try to write a detailed answer with your background in mind. This might not happen today.

14. Jun 21, 2017

### TheQuestionGuy14

I have a basic background. I studied General Relativity and touched a little on CTCs, I'd like to hear your detailed answer though.