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Time travel is self-suppressing
- atothayu 1y agobe here now maxxi
- PaulHoule 1y agoMakes me think of this Asimov classic where you really can change the past https://archive.org/details/dli.ernet.526852/mode/2up https://archive.org/details/dli.ernet.526852/mode/2up where it makes sense because people established an orthogonal dimension of time and this movie https://en.wikipedia.org/wiki/Predestination_(film) https://en.wikipedia.org/wiki/Predestination_(film) based on another Heinlein classic https://en.wikipedia.org/wiki/%27%E2%80%94All_You_Zombies%E2%80%94%27 https://en.wikipedia.org/wiki/%27%E2%80%94All_You_Zombies%E2... where you can't because it's all just a knot.
- cindyllm 1y ago[dead]
- warrenm 1y agoOf course you can "change the past" ... except you already did
- PaulHoule 1y agoLarry Niven wrote an essay about different theories of time travel in science fiction https://www.scribd.com/document/503128860/Larry-Niven-THE-THEORY-AND-PRACTICE-OF-TIME-TRAVEL-pt1 https://www.scribd.com/document/503128860/Larry-Niven-THE-TH... In some of them (like that Heinlein story) there is just one timeline and you at best get causal knots, in others (like Asimov’s End of Eternity) a time traveller experiences different timelines and whatever other experience is ‘undefined behavior’ I don’t think Nicen wrote stories about traveling into the past but plenty about traveling into the future with cold sleep, stasis boxes, and relativistic travel with Bussard Ramjets, I guess you could have done it even more stylishly if you could afford to buy the secret of the Outsider reactionless drive.
- Finnucane 1y agothey’ve all gone 4025, where the real party is.
- Hatrix 1y agoFuture people will have a Holodeck to simulate the past. No reason to actually go there.
- VincentEvans 1y agoMaybe they are all mostly dead and ever-more-feral survivors ridden by the crippling radiation- and pollution-borne genetic sicknesses are birthing still-born and slowly dying out while picking through the debris left from the civilizational collapse caused by global warming, ai, and the resulting world wars. And the last stronghold of civilization are genetically superior, warlike, numerous, but illiterate Tate descendants hidden in the mountains of Romania, unable to build anything more advanced than a cudgel used in the rituals to determine the alpha leader.
- bugbuddy 1y agoMost time travel theories ignore the fact that the earth is not fixed in space. It is moving relative to the sun in the solar system and the solar system is moving relative to the center of the galaxy, and the galaxy is… etc. A motion in each of these systems is not 100% accurately predictable forward or backward in time. This fact alone means that any time traveler is most likely to arrive in the middle of empty space.
- idle_zealot 1y ago> Most time travel theories ignore the fact that the earth is not fixed in space This is a misconception that bugs me. The problem isn't that the Earth isn't fixed in space, it's that there's no such thing as a fixed point in space. Position is only defined relative to other objects. If you're going to use time travel in a story or something then it has to use something like an anchor object to determine destination. I.e. the relative location of the traveler and the anchor is replicated from the future to the past.
- zamadatix 1y agoRelativity just says "nothing about space seems to require a preferred reference frame", not "such a thing as a preferred reference frame can't possibly exist". If we're allowing for the discovery of time travel in the story, I'm willing to allow for such a discovery as well. In reality I'd bet neither are realistic, but that's what makes the stories interesting.
- modzu 1y agotime travel backwards is impossible. but there are undoubtedly time travelers from the past going forward in time
- lordofgibbons 1y agoI've already been doing this for a while now ;)
- xlbuttplug2 1y agoHope you remembered to get extra plutonium. It isn't available at every corner drugstore yet.
- daedrdev 1y agoAll you need is to go fast to travel forward in time
- Apocryphon 1y agoLooking at the actual link itself, is this one of those papers that takes a thought experiment and tries to evaluate it using abstract mathematics/statistics? That's what it looks like it's doing. How is it actually useful to apply Markov chains to such unknowable suppositions? Is this analytical philosophy
- gchamonlive 1y agoMaybe you can only create rifts, and you need to create one before travelling back and forth. So only time travelling after the first time travel rift has been opened. Otherwise it'd break continuity. EDIT: If you created such rift and nobody would come out, then you'd have to start worrying.
- hashworks 1y agoWouldn't such a gate imply that an unlimited amount of entities would arrive at the time of the gate?
- selcuka 1y agoDoesn't any scenario of time travel imply an unlimited amount of entities? If you go back in time to observe (but not interfere with) your younger self, your younger self will get old and go back to that exact time too. So there will be an infinite number of your old selves observing your younger self. Not to mention that travelling back also means adding matter to the universe.
- warrenm 1y agomore or less how time travel in _Looper_ worked, iirc
- seba_dos1 1y ago> but not interfere with ...and how would you actually do that if we assume that your travel has added matter to the universe, rather than completed an iteration of a time loop that was happening there already?
- selcuka 1y agoYeah, "interfering with" is open to interpretation. One might argue that you don't have to say "hi" to yourself to interfere with, and it is sufficient to be within the same light cone.
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- mrandish 1y agoI've always suspected the reason is this century is just incredibly boring and literally nothing notable or even remotely interesting happens.
- jt2190 1y agoInteresting: > Therefore, I conclude that, assuming my model, time travel is self-suppressing: the timeline is continually rewritten until it inevitably reaches a timeline with no time machines ever being constructed. At this point, no further changes to the timeline are possible.
- lostmsu 1y ago> inevitably Fails right there. No strong argument was constructed to why this is inevitable.
- jmward01 1y agoI have always thought that time travel is a solution to the fermi paradox.
- Lerc 1y agoThis is just the one model of time travel, isn't it? It's a bit weird how it uses the notion of rewriting to continue until there can be no rewriting. If there could never be any rewriting then you still permit the single universe model of time travel. Things can only ever happen the way they happen, if that was because of a time traveller, it always was. It permits the grandfather paradox, but I can't help but think that this papers argument could be reshod to say the the grandfather paradox is self-suppressing.
- teeray 1y agoIt’s also possible the time traveling civilization was killed off by boiling the oceans to plagiarize the entire creative output of humanity.
- Workaccount2 1y agoI'm partial to the idea that time travelers need a "gate" to arrive at, and until we have that, no traveling to the past. However the universe really likes avoiding being forced to compute a paradox, so it may well be many timelines.
- 01HNNWZ0MV43FF 1y agoI loved that about the film Tenet. It's very grounded compared to say Terminator (not that I don't like Terminator)
- Melatonic 1y agoSame Dark Matter (the TV show) also does this very well (plus multiverses)
- JKCalhoun 1y ago"Primer" is arguably the best time travel film made/written.
- thedrexster 1y agothis!!
- ryandvm 1y agoYeah, time travel probably isn't possible, but if it is, limiting the time traveler to only being able to go back to when the machine was invented at least solves the "why haven't we met a time traveler" problem.
- selcuka 1y agoIt could also solve the "where will the extra atoms to instantiate a second copy of yourself come from?" problem if the machine uses some kind of filament to 3d-print the traveller.
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- retrocog 1y agoPerhaps time doesn't objectively exist in the way it is understood as a premise of the paper?
- warrenm 1y agoI would argue time only 'exists' as a convenient way to describe our lives (Incidentally, the Bible describes a singular Being Whom exists outside time.)
- Arcorann 1y agoThe conclusion is basically (Larry) Niven's Law of Time Travel. From "The Theory and Practice of Time Travel" (1971): > If the universe of discourse permits the possibility of time travel and of changing the past, then no time machine will be invented in that universe. The entire essay is worth a read, of course. Meanwhile the paper in the OP goes for a more mathematical approach.
- gnabgib 1y agoTitle: Where Are All The Tourists From 3025?
- rossdavidh 1y agoSubmitted by Andrew Jackson, presumably the President of the United States of the same name.
- cogman10 1y agoCould it be that time travel suffers from the dark forest problem? A hostile and aggressive alien species with time travel capabilities would naturally use it to go back in time and eliminate any evolved species that similarly discovers time travel. The energy required would definitely be enough to annihilate planets.
- wyldfire 1y agoTime travel, like flight and invisibility, are a product humanity's imaginative nature: "What if I were not bound by the laws of the universe, what could I achieve?" It's great for fiction, because of so many creative ways that you can structure your rules-violating-universe.
- tzs 1y agoThere was an amusing story in the July 1979 issue of Isaac Asimov's Science Fiction Magazine called "The Merchant of Stratford" about what it would be like for people who were visited by time travelers from the future. The Internet Archive has that issue [1]. Here's a summary from memory (which probably has some errors since I read the story in 1979). It's about the first time traveler. They decided the first trip will be to visit Shakespeare. Shakespeare has no problems accepting that he's being visited by a time traveler, and asks what gifts the traveler brings. The traveler is a bit confused, so Shakespeare explains that the early ones all bring gifts. The traveler has brought some gifts, including a nicely bound volume of Shakespeare's plays. Shakespeare looks at it, comments on the nice binding, says something about maybe he can sell it, then decides probably not, and tosses it on a pile of other such volumes brought by other time travelers. The first time traveler is now getting pretty confused, and says something like "but I'm the first time traveler!", to which Shakespeare answer "but not the first to arrive". This is something often overlooked in time travel stories--just because you are the first to leave for a given destination doesn't mean you are the first to arrive. Shakespeare mentions that he's frequently bothered by time travelers, but at least doesn't have it as bad as Jesus--that guy can barely do anything without a time traveler showing up. Shakespeare explains he knows because a time traveler thought it would be interesting to take Shakespeare to meet Jesus once. All the great figures of history are frequently visited. Somewhere in there Shakespeare provides some drink and tries to calm down the inexperienced time traveler, who is freaking out over all this. Shakespeare is an old hand at dealing with newbie time traveler freak outs. Then a bunch of other time travelers arrive, but not to see Shakespeare. They are reporters from the first time traveler's future, there to interview him about his historic visit to Shakespeare. [1] https://archive.org/details/Asimovs_v03n07_1979-07/page/n123/mode/2up https://archive.org/details/Asimovs_v03n07_1979-07/page/n123...
- zelias 1y agowouldn't backwards time travel merely create an alternative timeline? for all we know, we simply live in the timeline that had to exist prior to the invention of time travel technology itself
- elcdodedocle 1y agoI like the approach taken by several authors from Asimov in "The End of Eternity" to Star Trek or Loki on TV: Time travel is not allowed except for entities that live outside of time in a way that is not meaningfully perceived by anyone else; When unsanctioned travel happens, it is easy to detect and retroactively suppress by these entities. Of course this can all be refuted or at least declared a transient state at most by the mess Time Cop is; Or how things end up in any of the other stories.