10 ms·
> Researchers ran the numbers and determined that even if you made a change in the past, the timeline would essentially self-correct, ensuring that whatever hap
by MetaWhirledPeas 6y ago
> Researchers ran the numbers and determined that even if you made a change in the past, the timeline would essentially self-correct, ensuring that whatever happened to send you back in time would still happen.
I'm sure these researchers are pretty smart, but nothing in this article goes beyond the level of a grade-school debate. Maybe there's something enlightening in the paper. But if there was, you'd think it would make its way into the article.
- paxys 6y agoExactly. The article mentions the grandfather paradox, but doesn't really address it at all. Can't "self correct" shooting your past self in the head.
- mpalmer 6y agoThink what they're getting at is that it won't happen that way. Gun will jam, you die of a brain aneurysm. We don't exist in a universe where impossible things happen, so we can't bring them about. But yes, the article doesn't really sink its teeth into it.
- henrysarabia 6y ago"The past is obdurate." This concept is narritively explored in Stephen King's "11/22/63" if anyone finds this interesting. The novel is an entertaining read and the audiobook available on the Libby app (requires a local library card here in the US) is high quality.
- croon 6y agoThere's also a James Franco mini series based on the book, which is alright albeit a bit slow moving.
- im3w1l 6y agoI could see how a universe with such rules could exist. But is it our universe? In the universe you describe, wouldn't we already have seen time travellers from the future? The only explanation I can think of for why we haven't seen any, if we live in such a universe, is that we need to build an "arrivals hall" first, and that as soon we manage to do that, people from all over start popping in for a visit.
- Uehreka 6y agoI can’t see how a universe like that could exist. Perhaps if some time-traveler was unlucky, their gun might jam, but I can’t figure out how you could successfully thwart a “well-prepared time traveler” who knows all the details of the situation they’re jumping into and has double-checked their gun after making the jump.
- falseprofit 6y agoIsn't the point that that guy thwarts himself.
- im3w1l 6y agoFirst consider that a gun is just a dramatic way of illustrating the concept. If a butterfly travels back in time and flaps its wings it could cause a tornado on the other side of the world (butterfly effect). A gun merely jamming solves nothing. Either the time traveler was there "the first time around" or he must be stopped from going back somehow. Because the first and the second time around must be exactly identical.
- tremon 6y agoThe logical extension of this would be, given how local interactions might affect events across the globe over time, that the entire past becomes immutable. That would reduce time travel to a read-only experience, so it wouldn't have any utility beyond time tourism.
- account42 6y agoRead only time travel would still be immensely useful as there are so many situations where having a clear answer to what happened is interesting - history, solving crimes, analyzing accidents (or bugs as we are on HN), re-measuring experiments, ...
- at_a_remove 6y agoThe thing about this "self-correction" is that nobody, but nobody has a mechanism to explain this force. Not how it works or worse yet, how it will know how to self-correct. What particular force decides that the friction on some surface will briefly rise and cause the gun to jam? How does it know to do that? In all of the paradox-forbidding time travel scenarios, nobody has ever mentioned anything deeper than "Well, uh, reality just won't let that happen." If I right now posit that each time travel scenario spawns an intelligent angel whose sole job it is to dash about a closed timelike curve invisibly nudging away paradoxes through minuscule miracles of improbability, that's quite literally more than you'll see written about in these situations.
- hderms 6y agoI always thought the idea was some kind of many worlds style event where whatever universe you find yourself in after the split is guaranteed to be paradox free because something must have happened to have prevented it
- deleted 6y ago[deleted]
- notahacker 6y agoThis. As far as we're aware, physics doesn't understand narrative, and doesn't see any difference between killing a person, moving a gun or even disturbing a speck of dust: all entail things being in the wrong place compared with the original timeline. You might expect some similarities on a macro scale regardless: perhaps if you kill baby Hitler, Germany can still be expected to end up with a different right wing leader who invades Poland, perhaps even assisted by people who were prominent Nazis in our time, and maybe even loses to the same allies for the same reasons. But on a micro level the differences are huge: the dates will be different, people dying will be different, and the rest of the twentieth century will be different. A century of different atoms bumping into different atoms, different sperm are getting to the front of different queues, and different people being influenced into different decisions results in a different world. Our would-be time traveller isn't even born, never mind motivated to look for Ms Schiklgruber's illegitimate child.
- dragonwriter 6y agoThe thing is, the time traveler’s existence in the past is a contradiction, so if the universe prevents contradictions it must prevent backwards time travel absolutely.
- ralfn 6y agoYeah I fail to see anything addressed at all. Just fluff words and old sci fi trope. How is this presented as something published in a peer reviewed journal. Is the article completely misrepresenting the research or is the research itself this level of nonsense. I must be missing something here.
- me_me_me 6y agoSo this is essentially magic. Any self correcting mechanism implies magic. How does 'universe' know what needs to be done to fix timeline?
- AnIdiotOnTheNet 6y agoHow do particles in delayed-choice quantum eraser [0] experiments know whether or not their path will eventually be observed? If we accept "magic" as an explanation, then it would appear based on experimental evidence that the universe is, in fact, magic. [0] https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser https://en.wikipedia.org/wiki/Delayed-choice_quantum_eraser
- me_me_me 6y agoWe don't know how it work. That's it. Unless someone comes up with testable idea. But inserting as a cause magical forces that we cannot even begin to explain as means of correcting time discrepancies. So whats the point concocting hypothesis that there is no issues with time paradox all based on unknown? Its a plot for a SciFi novel not a paper. I don't want to come across as a party-pooper, but those are outrageous claims with no meat and no bones.
- AnIdiotOnTheNet 6y ago> But inserting as a cause magical forces that we cannot even begin to explain as means of correcting time discrepancies. That is my point though: there is no need for magic for this mechanism. The double slit delayed choice quantum erasure experiment is analogous to time travel as there is no way the particles could "know" that their path would be observed at some point in the future, yet if they were, those particles mysteriously only took paths that created the gaps. Given that this is a real, testable phenomenon in the real testable universe, it would not require magic to explain that idea that only timelines in which a time traveler doesn't cause a paradox can exist. The time traveler, like the particles in the experiment, chooses paths as they see fit and it only later turns out that they necessarily were ones in which paradoxes were avoided.
- mamcx 6y agoI know nothing, so this instead is my theory: The universe is a VM alike smalltalk. What you have now, is the action of the chain of actions of the past. The VM of now is done. You travel back. Arrive at the VM of the past, WITH THE STATE of the past. You mutate state. It work as expected, you die. But in the STATE of now, you are alive. When the time traveler exit the VM, the VM go nowhere. It already happened now, but ONLY "remember" the changes of IT, not of the OTHER vm. Assorted musings: For a short time, the universe get splitted(?) The STATE run on RAM, and that is why it not "push to the future" because is NOT persisted? The universe is multi-core, and time travel is possible because unused computation time that is assigned to the past VM when suddenly it get awakened? If the STATE is not persisted (to make all this work), how this make sense at all? Or it have snapshots (backup) and you load for a moment the past?
- gremlinsinc 6y agoIt also pre-supposes that you aimed to kill your grandfather. Perhaps you accidently did this. The reason for you going back in time still exists. However, I believe the worst that could come of this would be to split the timeline in the case that string theory and multiverses exist where the timeline we return to is one that is different than the one we came from. What if we really are living in a simulation? Could it be possible that any moment we arrive in the past would possibly have a random outcome on the future? What if every choice from the moment you arrive to the moment you left could have a random effect, and thus the world you arrive back at if it is a closed loop could be different as night and day, simply because all events that happened after your arrival were erased and all choices were given a second chance to arrange themselves like coin tosses mixed with end-user free agency. If that were the case, how would you prove that it's a randomized closed loop vs string theory since to you the time-traveler, everything has changed which the easiest reason would be you're in a different timeline. It never dawned on you that events along the timeline could be shuffled at anytime and are inconsequential to how the universe works because we're actually in a simulation.
- markus_zhang 6y agoI think it's still a lot easier to treat each going-back-to-the-past as a fork().
- forgingahead 6y agoGiven that this is NPR, a reference to Gell-Mann amnesia[0] seems appropriate: “Briefly stated, the Gell-Mann Amnesia effect is as follows. You open the newspaper to an article on some subject you know well. In Murray’s case, physics. In mine, show business. You read the article and see the journalist has absolutely no understanding of either the facts or the issues. Often, the article is so wrong it actually presents the story backward—reversing cause and effect. I call these the “wet streets cause rain” stories. Paper’s full of them. In any case, you read with exasperation or amusement the multiple errors in a story, and then turn the page to national or international affairs, and read as if the rest of the newspaper was somehow more accurate about Palestine than the baloney you just read. You turn the page, and forget what you know.” [0]: https://www.epsilontheory.com/gell-mann-amnesia/ https://www.epsilontheory.com/gell-mann-amnesia/
- nimbleal 6y agoI didn’t know this had a name, but it’s long been a cause of amusement (or despair!) for me. I too have noticed that any time I read an article on a subject on which I have even a passable level of expertise, I find it chock-full of errors.
- deleted 6y ago[deleted]
- pontifier 6y agoI take it with a grain of quantum physics. When traveling back in time you are entangling the state of the moment of time travel with a past state of the universe, and the universe must collapse into a steady state with a single history... The history in which the time travel did nothing.