# New Research Shows That Time Travel Is Mathematically Possible **URL:** \ **Category:** Factual Questions\ **Created:** [March 8, 2018, 8:26am UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228 "2018-03-08T08:26:27Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 9, 2018, 7:43am UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/41 "2018-03-09T07:43:41Z")
> [@Little\_Nemo](#): > > I’m traveling through time as I write this post. The secret is to maintain a steady pace into the future. It is possible to jump back a minute though - I’ll show you… scroil up a bit. ---
**Author:** ![Crane](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crane/32/3495_2.png) [@Crane](https://boards.straightdope.com/u/Crane)\ **Post date:** [March 9, 2018, 1:06pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/42 "2018-03-09T13:06:15Z")
OK, so there’s a time machine - is the time traveler in a time shield? Whatever the math, the future beyond 100 years does not contain the time traveler. ---
**Author:** ![Gyrate](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gyrate/32/3588_2.png) [@Gyrate](https://boards.straightdope.com/u/Gyrate)\ **Post date:** [March 9, 2018, 1:21pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/43 "2018-03-09T13:21:35Z")
> [@Riemann](#): > > Why? The fact that a path is stochastic does not imply that all possible paths in the distribution actually occur. Many worlds is only one possible interpretation of QM. So you’re saying that there may exist a world in which the “Many worlds” theory is false? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 9, 2018, 1:53pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/44 "2018-03-09T13:53:52Z")
> [@](#): > > Quoth **Crane** : > > Whatever the math, the future beyond 100 years does not contain the time traveler. Well, it doesn’t if the traveler doesn’t go there. But it’s really easy to go there-- Why wouldn’t he? > [@](#): > > Quoth **Cartooniverse** , 25 and a half hours ago: > > Indeed, there is no future to visit. It looks like **Cartooniverse** of 25 and a half hours ago is now proven wrong, because here we are now in his future, and it most certainly does exist. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [March 9, 2018, 2:45pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/45 "2018-03-09T14:45:51Z")
> [@MichaelEmouse](#): > > What does it mean for something to be mathematically possible? A scientist in the linked article uses this phrase but there is no explanation. There is a link to the abstract of the published paper but you must pay to get the full article. I think in this context it means that [the authors believe that] there is a mathematical model that shows that this sort of time travel is possible, but that the technology to implement it is not available and maybe even infeasible. It is mathematically possible to accelerate a school bus to 0.999c but it ain’t never gonna happen. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [March 9, 2018, 2:47pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/46 "2018-03-09T14:47:44Z")
What did the OP do to get banned? It was only his second post. ---
**Author:** ![k9bfriender](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k9bfriender/32/3283_2.png) [@k9bfriender](https://boards.straightdope.com/u/k9bfriender)\ **Post date:** [March 9, 2018, 2:49pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/47 "2018-03-09T14:49:39Z")
> [@Weisshund](#): > > I’d think the bigger draw back is you slow your personal flow of time to a crawl > but everyone elses continues at normal speed, so no matter where you end up, when you turn around and come back, everyone you wanted to tell about it is dead and gone, and no one that is here cares who you are. ☹ It’s a drawback if you have friends and family that you would want to see again. Less a drawback if the point is to outlive your enemies. > [@jtur88](#): > > I’m not sure you simply take that as a given, and use it to disprove another theory. Certain futures may be inexorable, to a degree of certainty that their denial is untenable. For example, the light from a star, which is now 186,000 miles from my present position, will reach me one second in the future, and the principles of the theory (although I haven’t read them) that in the existing universe governed by the accepted laws, nothing can stop it. Just as certainly as “there is no future”. Not if I put an opaque barrier between you and the star. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [March 9, 2018, 3:25pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/48 "2018-03-09T15:25:55Z")
If time travel is possible, where are they? ---
**Author:** ![Gyrate](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gyrate/32/3588_2.png) [@Gyrate](https://boards.straightdope.com/u/Gyrate)\ **Post date:** [March 9, 2018, 3:56pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/49 "2018-03-09T15:56:14Z")
> [@CookingWithGas](#): > > What did the OP do to get banned? It was only his second post. IANA Mod and I haven’t checked but it looks like he was spamming a website, particularly if he was posting the same messages across multiple boards. Or maybe he was an unauthorized time traveller and \*\*Chronos \*\*is a Time Cop. It would certainly explain the name. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 9, 2018, 5:14pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/50 "2018-03-09T17:14:52Z")
Nobody has ever mentioned the possibility that I’m a Time Cop. And if they have, then I’ll make sure that nobody has ever mentioned it. Understood? ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [March 9, 2018, 6:24pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/51 "2018-03-09T18:24:37Z")
> [@Gyrate](#): > > IANA Mod and I haven’t checked but it looks like he was spamming a website, particularly if he was posting the same messages across multiple boards. IAAlsoNAM, but this would be my guess. Both the consistent posting of pointers back to that particular “news aggregator” clickbait factory, and the fact he never engaged again after OP, seem to my un-moderator eyes to be spam hallmarks. The fact he did it slowly is no defense. (The fact that the target spammed website was serving up old garbage is neither here nor there, but IMHO did no favors.) Nota bene: In my limited experience, no moderator will discuss the reasons for the banning ex cathedra in an open forum, not even in ATMB. If anyone is sincerely curious, I believe a private message is the way to go. (Again, not a moderator, but relaying my own experience and recollection.) > [@](#): > > Or maybe he was an unauthorized time traveller and \*\*Chronos \*\*is a Time Cop. It would certainly explain the name. In our hearts, I think we all knew this already. It explains a lot, if you think about it. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [March 9, 2018, 7:45pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/52 "2018-03-09T19:45:46Z")
> [@Asympotically\_fat](#): > > Without meaning to be overly critical, this argument to me doesn’t really make sense. Chaos theory broadly is about how in certain systems small changes to initial conditions result in much larger changes to later conditions, but an acausal spacetime (i.e. a spacetime with closed causal curves) cannot be described by the development of initial conditions. In other words chaos theory is a redundant concept when “time travel” is involved. I don’t understand this criticism, which may well be my own failing. Regarding spacetime as a closed timelike curve does not imply that it is acausal ([cite 1](https://arxiv.org/abs/1008.1127), [cite 2](https://www.nature.com/articles/npjqi20157)). If that were so, we would not have the “grandfather paradox”, and if we speak of the grandfather paradox, then ISTM that we admit to a set of initial conditions at some past time. I’m simply suggesting that we need not engage in something so drastic as killing our own grandfather to create a causality paradox, but that any perturbation of those conditions whatsoever, however small, would lead to an evolution of circumstances described by chaos theory, and so to a different future. ---
**Author:** ![Asympotically\_fat](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Asympotically\_fat](https://boards.straightdope.com/u/Asympotically_fat)\ **Post date:** [March 9, 2018, 9:26pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/53 "2018-03-09T21:26:31Z")
> [@wolfpup](#): > > I don’t understand this criticism, which may well be my own failing. Regarding spacetime as a closed timelike curve does not imply that it is acausal ([cite 1](https://arxiv.org/abs/1008.1127), [cite 2](https://www.nature.com/articles/npjqi20157)). If that were so, we would not have the “grandfather paradox”, and if we speak of the grandfather paradox, then ISTM that we admit to a set of initial conditions at some past time. I’m simply suggesting that we need not engage in something so drastic as killing our own grandfather to create a causality paradox, but that any perturbation of those conditions whatsoever, however small, would lead to an evolution of circumstances described by chaos theory, and so to a different future. Spacetimes can be categorized by causality conditions, three of which are: Chronological: no closed timelike curves Causal: no closed causal curves Globally hyperbolic: admits a set of global initial conditions whose evolution describes the spacetime. If a spacetime is globally hyperbolic, then it is causal and if it is causal it is chronological. Therefore being able to talk about (global) initial conditions precludes the existence of timelike curves. You can have partial initial conditions even when there are CTCs, but the reason their evolution does not describe the spacetime is because there is additional information contained in the CTCs. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [March 9, 2018, 9:30pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/54 "2018-03-09T21:30:23Z")
> [@Chronos](#): > > Nobody has ever mentioned the possibility that I’m a Time Cop. Funny, I always imagined you were a member of the [Campaign for Real Time](https://sites.google.com/site/h2g2theguide/Index/c/979829). ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [March 10, 2018, 12:34am UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/55 "2018-03-10T00:34:29Z")
> [@Hari\_Seldon](#): > > If time travel is possible, where are they? Warren Buffet is here from the future making investments to become the world’s third richest man. Jules Verne traveled back in time to 1863 and wrote _Paris in the Twentieth Century_, predicting air conditioning, TV, and sort-of the Internet. Then he wrote _From the Earth to the Moon_ describing the Apollo flight to the moon. Leonardo da Vinci traveled back in time to the 1400s to invent the helicopter before there was technology to build one. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [March 10, 2018, 12:55am UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/56 "2018-03-10T00:55:10Z")
Sigh. Take any simple graph. You can model that graph with any number of equations. By the time you get to equations with 8th or so order coefficients, you can probably make your model go through every point. Your model may be worthless for anything off the edge of the graph. Take our observations about reality. All physics is is a model. It is incomplete and things like the conditions for time travel are really, really off the edge of the graph. So our models are unlikely to be correct. (given the current modern theory of physics is pretty solid and predictive I say _unlikely_, but it \*could \*be correct) Or it could simply be that no possible way to make negative energy or mass exists. None, reality doesn’t have it. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [March 10, 2018, 2:57am UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/57 "2018-03-10T02:57:20Z")
I just find the nearest 0 and divide by it. It works every time. ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [March 10, 2018, 9:03am UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/58 "2018-03-10T09:03:57Z")
> [@ftg](#): > > Funny, I always imagined you were a member of the [Campaign for Real Time](https://sites.google.com/site/h2g2theguide/Index/c/979829). Nah, Chronos was the God of time until Sam Winchester came along. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [March 10, 2018, 12:44pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/59 "2018-03-10T12:44:14Z")
it’s amusing to me to see how much time has been spent trying to theorize things which began as little more than convenient ways to move along the plots of sci-fi works. > [@Chronos](#): > > One possible resolution to the “Grandfather Paradox” is that any time you try to set up such a paradox, something happens (possibly with no apparent causal relationship to what you’re doing) that prevents it. Maybe, for instance, you just happen to die of a brain aneurysm just as you’re about to tell your previous self what you wrote. The aneurysm wasn’t exactly caused by your time travel, but timelines where the aneurysm didn’t occur simply don’t exist. “I could come back a thousand times… and see her die a thousand ways.” “You built your time machine because of Emma’s death. If she had lived, it would never have existed, so how could you use your machine to go back and save her? You are the inescapable result of your tragedy, just as I am the inescapable result of you.” ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [March 10, 2018, 12:49pm UTC](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228/60 "2018-03-10T12:49:06Z")
> [@Cartooniverse](#): > > That said, I also embrace rigorous science in the real world. There is no future because many animals including Homo sapiens are endowed with free will. Firstly there is no evidence that we have free will and actually several things that seem to go against it. But secondly, and what I want to focus on is: why do you suppose free will would preclude time travel? After all, you’re travelling forwards in time right now at 1 second per second, so “moving through time” and “free will” must necessarily not be inconsistent. Regular dopers will know that my view on free will is that the concept itself is incoherent, and the sentence “There is no free will” is simply meaningless. And here, the assertion that time travel must be incompatible with free will, and the fact many posters seemed to implicitly agree, illustrates just what I’m talking about. I think “free will” has some vague notion of freedom in people’s minds, and many assert this or that depends on free will, while never actually defining clearly what it is. [Previous page](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228.md?page=2) [Next page](https://boards.straightdope.com/t/new-research-shows-that-time-travel-is-mathematically-possible/810228.md?page=4)