Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

Imagine I exist at time $t_1$ and my mass is $m$. At time $t_2$ I time travel back to $t_1$. At time $t_1$ there is now a net increase of mass/energy in the universe by $m$.

At time $t_3 = t_2 - x$ where $x < t_2 - t_1$, I travel back to t1 again. The net mass in the universe has now increased by $2 \times m$.

Properly qualified, I can do this an arbitrary $n$ number of times, increasing the mass in the universe by $n \times m$. This extra mass, of course, can be converted to energy for a net increase in energy.

Does this argument show that traveling back in time violates the conservation of mass/energy?

share|improve this question

closed as off-topic by BMS, Brandon Enright, BebopButUnsteady, Kyle Kanos, David Z May 1 at 5:41

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "We deal with mainstream physics here. Questions about the general correctness of unpublished personal theories are off topic, although specific questions evaluating new theories in the context of established science are usually allowed. For more information, see Is non mainstream physics appropriate for this site?." – BMS, Brandon Enright, BebopButUnsteady, Kyle Kanos, David Z
If this question can be reworded to fit the rules in the help center, please edit the question.

    
There is a related concept for wormholes about a feedback loop amplifying virtual particles and destroying it. See part of en.wikipedia.org/wiki/Wormhole#Time_travel –  Brandon Enright Apr 30 at 20:24
    
I actually wanted to close this as "unclear what you're asking" (there's no question in it), but the consensus among others was non-mainstream. Regardless, I think this does need some edits. –  David Z May 1 at 5:42
    
Thanks for the clarification, David. I was confused regarding the reason below, because there are numerous other questions about time travel on this site. –  yters May 1 at 18:35
    
For those who put my question on hold due to being off-topic, can you point out what is not established science in my question? That way I can reword it to fit within the guidelines. –  yters May 1 at 19:55

1 Answer 1

up vote 1 down vote accepted

Conservation of Energy is a consequence of Time-translational Symmetry of the system. If this symmetry is broken, there'd be no Conservation of Energy.

share|improve this answer
    
You can still have time translation symmetry in a chronology violating spacetime, the simplest case being the torus spacetime $S \times \mathcal{M}$. If you assume really basic classical behaviour though, there needs not be violation of conservation of energy, at least in the GR sense. But you may not be able to create time paradoxes willy nilly. –  Slereah Apr 30 at 20:35
    
@Slereah Time-translational Symmetry is more than geometry of Spacetime. If your worldline is in loop, you're going to crash with yourself. How can GR explain extra mass crashing with original mass? The challenge in time travel isn't twisting Spacetime.. But, it is the flaw in the concept. –  Sachin Shekhar Apr 30 at 20:50
    
So does the "law" of conservation assume time travel is impossible, if the two are mutually exclusive? –  yters Apr 30 at 22:34
    
@yters Actually, conservation laws don't dictate the possible/impossible things in the universe. See Spontaneous Symmetry Breaking events, for example. The thing is: We don't have a solid theory for time travel. But, it can exist successfully violating conservation laws. –  Sachin Shekhar Apr 30 at 23:11
    
To expand on your answer, I found this question discussing the conditions for conservation. physics.stackexchange.com/questions/296/… –  yters Apr 30 at 23:48

Not the answer you're looking for? Browse other questions tagged or ask your own question.