Time Travel Simulation May Have Solved "Grandfather Paradox"

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Time Travel Simulation May Have Solved "Grandfather Paradox"

Closed Timelike Curve

Always wanted to go back in time and kill your grandfather? The possible results might not be quite what you expected.

Recent experiments conducted regarding the possibility of time travel could provide a mathematical explanation for the theoretical phenomenon. The study operates using the most basic understanding of the universe, and the conclusion that time travel may be feasible could have profound implications for fundamental physics along with practical applications for quantum cryptography and computing.

The origin of time travel debate lies in the fact that our best physical theories appear to have no restrictions on backwards time traveling. Einstein's theory of relativity, which describes gravity as the warping of spacetime by energy and matter, supports that possibility. An extremely powerful gravitational field, like one generated by a spinning black hole, could warp the fabric of existence in a way that bends spacetime back on itself. This would create a "closed time-like curve" (CTC), a loop that could be traversed to travel back in time.

A model created by theorist David Deutsch in 1991 proposed the paradoxes created by CTCs could be avoided at the quantum scale thanks to the flaky quantum behavior of fundamental particles. Recently, physicist Tim Ralph from the University of Queensland and his PhD student Martin Ringbauer led a team that experimentally simulated Deutsch's model of CTCs for the first time, which tested and confirmed many aspects of the theory. Much of their simulation revolved around investigating how Deutsch's model rationalized the "grandfather paradox", in which someone uses a CTC to travel back through time to murder his or her own grandfather, thus negating his or her own existence.

The solution can be explained like this: Instead of a human being going back to kill the ancestor, imagine a fundamental particle goes back in time to reverse the particle-generating machine that created it. Due to the reversal, the machine emits a particle-the particle-back into the CTC. Deutsch insisted that any particle entering one end of a CTC must emerge at the other end with identical properties. Therefore, a particle emitted by the machine with a probability of one half would enter the CTC and come out the other end to reverse the machine with the same probability value, imbuing itself at creation with a probability of one half of going back to flip the switch.

If the particle were a person, that person would be born with a one-half probability of killing their grandfather, giving their grandfather a one-half probability of escaping demise; a good enough probability to close the loop and escape the paradox.

Source: Scientific American

For more info on Ralph's and Ringbauer's findings, check out their published work in Nature Communications. For more time travel paradoxes to wrap your head around, check out CJ Miozzi's 5 Time Travel Paradoxes That Will Induce Headaches.

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Interesting. A quantum explanation for Anubis Gates style time-travel: you can totally go back in time and try to kill your grandfather, but you'd never actually succeed.

This just caused a bit of brain-ache, as it still seems to allow for the paradox, albeit with a 50% less chance of it occurring?

And today's migraine fuel, brought to you by Science!

Thought I understood it, then thought about it for too long.

The grandfather paradox was always a weird concept to me. Why your grandfather? why does it have to skip a generation? I guess the "Father Paradox" doesn't sound as good?

Doesn't this assume time doesn't branch? or not considering the multiple dimensions theory? Personally i still prefer Hawkin's explanation that backwards time travel is impossible.

Or if it does work the multidimensional theory is more attractive. Any alterations you make to the pass puts you on a different "timeline." It gets rid of the paradoxes altogether. Everyone is happy :D

DTWolfwood:
Doesn't this assume time doesn't branch?

Well, yes. There's no paradox in any branching scenario.

DTWolfwood:
Personally i still prefer Hawkin's explanation that backwards time travel is impossible.

There really isn't any reason to think it's actually possible, given that it would require quite substantial concentrations of negative energy.

[Insert Dumb and Dumber meme here]

I would love for time travel to become useable in my lifetime. But I'll settle for space travel I guess.

Heck, at this point I'm just hoping for a god damn jetpack that I can buy and use at my own discretion.

That's suitably wibbly and wobbly.

Noelveiga:
That's suitably wibbly and wobbly.

don't you mean "timy whimy"?

same joke, nevermind

So within the confines of a simulation, itself based entirely on a hypothetical ruleset, it's not an issue. Good to know. But this is meaningless unless they can confirm that the experiments parameters are themselves true to life.

P.S. Thanks

"Mathematical understanding"

I lol'd. That's expecting that Maths is universal and still works at this sort of level. Even then, Maths only deals in absolutes, which usually relates to irrelevancies, such as this one(in this particular field mind, I'm not dismissing the entire discipline).

I don't know what surprises me more; the fact that scientists have found a probable answer to the Grandfather paradox, or the fact that I actually understand it.

Science, will I ever stop loving you? I hope for my sake that I do not.

*yawn*

Heard this a billion times before. Still sounds stupid.

"You can go back in time, because it's still somehow immune to paradoxes for reasons."

It hasn't progressed at all in decades. It's just the same handful of theories over and over again, until they come up with something stupid like string theory, which makes even less sense. It's time we accepted that black holes just have super gravity, and photons have mass.

Sounds like just a matter of semantics, not any actual new research or evidence of anything.

Sounds like an invocation of Shroedinger and Heisenberg to state that one might get away with temporalcide without the negation of personal existence, but it is uncertain how or what happens afterwards.

Methinks someone dwelt on an episode of Futurama way too much. Call me when you can prove this. Except you won't, because even if you manage to make a time machine, a mullet-sporting Jean Claude Van Damme will come to arrest you.

The image reminded me of another I've seen for a movie that might interest anyone that likes time travel and the such - Primer. The two seem very similar, actually.

image

Sorry the text is a bit small. I think it's still easy enough to read. Anywho, the movie takes a fairly grounded and realistic approach to time travel compared to others and lays on the science very thick.

... Astrophysics have officially jumped the shark. We need a new Einstein and a new set of fundamentals, these guys are just playing Magic: The Gathering with their minds at this point.

I'm glad I'm not the only one who wasn't impressed by this. Also, isn't it dodging the question to use particles for an example because of the inherent issues with not really understanding how quantum physics and "normal" physics interact(The Theory of everything)?

Rocket Girl:
The image reminded me of another I've seen for a movie that might interest anyone that likes time travel and the such - Primer. The two seem very similar, actually.

image

Sorry the text is a bit small. I think it's still easy enough to read. Anywho, the movie takes a fairly grounded and realistic approach to time travel compared to others and lays on the science very thick.

That was the most comprehensible explanation of primer i have seen.

Time travel is more fiction than science, Time is simple the movement of mass in space. Once something is moved it cannot be unmoved.

Why yes, I know some of those words!

The only part I don't like is "that person would be born with a one-half probability of killing their grandfather, giving their grandfather a one-half probability of escaping demise" Meaning it could happen or it could not. Which IS the paradox in itself. We knew this going into the study.

raises 2 questions in my mind, who gave them the funding for this and if i start a project to see if i can eat the same doughnut twice can i get some?

its a long quote but its funny so ill leave you with Mr Douglas Adams view on this whole time travel debate.

"One of the major problems encountered in time travel is not that of becoming your own father or mother. There is no problem in becoming your own father or mother that a broad-minded and well-adjusted family can't cope with. There is no problem with changing the course of history-the course of history does not change because it all fits together like a jigsaw. All the important changes have happened before the things they were supposed to change and it all sorts itself out in the end.

The major problem is simply one of grammar, and the main work to consult in this matter is Dr. Dan Streetmentioner's Time Traveler's Handbook of 1001 Tense Formations. It will tell you, for instance, how to describe something that was about to happen to you in the past before you avoided it by time-jumping forward two days in order to avoid it. The event will be descibed differently according to whether you are talking about it from the standpoint of your own natural time, from a time in the further future, or a time in the further past and is futher complicated by the possibility of conducting conversations while you are actually traveling from one time to another with the intention of becoming your own mother or father.

Most readers get as far as the Future Semiconditionally Modified Subinverted Plagal Past Subjunctive Intentional before giving up; and in fact in later aditions of the book all pages beyond this point have been left blank to save on printing costs.

The Hitchhiker's Guide to the Galaxy skips lightly over this tangle of academic abstraction, pausing only to note that the term "Future Perfect" has been abandoned since it was discovered not to be."

As I understand it, that would mean that the outcome would vary between loops over whether the grandfather dies or not. So would the grandson within a one-half probability loop where he succeeds just go on existing then?

o_o

I can in fact confirm the use of words in that news story, they even seem to be in English, as to what they mean, I have NO fucking clue

Is this really recent? I've seen people reason FFVIII's plot like this for years.

Ah, gravity. It keeps you from flying off into space and it can warp the fabric of space-time to create a time portal if you get enough of it in one place. No other force gonna do that!

And it's still the weakest of the four known forces in the universe.

This sounds like something from Chrono Cross.

I feel like if backward time travel were possible, we'd have already met time travelers and seen the effects of it. I don't know why we keep trying to work out the paradoxes when nobody has any idea of how the mechanics of it would work. It's like designing traffic regulations for a vehicle that doesn't exist yet.

I also find it amusing that alot of these posts are "I find this confusing". It's like a bunch of kids in a class putting up their hands going "OOOH! OOOH! I don't know."

Maybe I'm just a big ol' stupie-head, but to me it just sounds like they're saying the grandfather paradox can be avoided by you simply being unsuccessful in killing your grandfather.

... Well... Duh? o_O

LOL this article is wrong, their explanation is for the quantum physics which are not valid in the macroscopic level. Both are obviously entirely different things (i.e. are you solid? do you continuously exist trough a period of time?)

Ylla:
LOL this article is wrong, their explanation is for the quantum physics which are not valid in the macroscopic level. Both are obviously entirely different things (i.e. are you solid? do you continuously exist trough a period of time?)

That's exactly what I was going to say.

Quantum physics, by its very definition, can only be applied to sub-atomic particles. Any larger scale than that and it completely falls apart, which was the whole point of Schroedinger's cat as a thought experiment: it isn't supposed to make sense. It would be like saying "the electrons in my body are moving at thousands of kilometers a second, so why can't I run that fast?"

Err.... why would a gravity field actually allow to GO BACK in time?

If they said you can park in the gravity well for a few years and have the outside world move on for a few thousand, well sure i can see that being plausible but actually going back?

Try to imagine the proxess involved. The physical process of how this is supposed to look.

Do you fly into the hole, veer off at an angle and use the slingshot to get out again and voila you are in the past?

Doesnt that, like, do the opposite? Deposit you in the future because your stupid ass just spent some time in time dilation?

Someone explain that to me when they say "bend space time". Isn't time purely a concept of the human mind?

And why a spinning black hole? What the fuck does spinning have to do with gravity?! Centrifugal forces are not gravity. Thats inertia of mass transformed into getting flung the fuck away?

???

And why does everyone wanna go kill their parents and grandparents? Can't you go kill hitler or something? I mean i am sure we can find better targets for temporal assasinations than granny and gramps.

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