Maybe 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 · 1h ago
Most 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 · 52m 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.
bugbuddy · 27m ago
We would assume that the time-space traveler would have to tell the machine both the time and space directions from their current position in time and space. Assuming the time-space traveler cannot stop to observe his or her “location” in time-space coordinate along the way in small increments, he would have to calculate the entire travel trajectory beforehand.
I am saying this trajectory calculation relative to current coordinates is impossible. Even modern satellites with super precise instruments still need regular ongoing “adjustments.” Time travel requires many order of magnitude more precision than satellite orbital maintenance.
do_not_redeem · 12m ago
Go backwards in time 15 minutes at a time. At this short distance your calculation error will be small, and you can land your hovercraft back on earth to correct for any drift. Then go backwards another 15 minutes, repeat ad infinitum. Even present day aircraft have autopilot, so surely this can be automated too.
zamadatix · 37m ago
Relativity 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.
gmane · 49m ago
I'll give a half-baked counter to this: we know gravity impacts the flow of time through relativity. There is currently no evidence that time travel wouldn't be impacted by gravity in some way. Maybe the way time in time travel interacts with gravity protects you from this problem? Probably not, but it has just as much evidence to support it as your claim of time travel will dump you in empty space.
throwaway173738 · 40m ago
You’re positing some unknown influence will cause everything to work out well in the ends without any evidentiary basis. Occam’s Razor suggests that you’re more likely to be wrong than parent.
Of course the idea that your point of origin must be fixed from time A to time Z if you’re willing to allow for time travel is itself flawed. If you could somehow move an object to an arbitrary time you could move them to an arbitrary point in space, and your ability to calculate may be significantly greater on the grounds that you’d have more advanced technology than us. It’s all scifi woo though until someone actually time travels.
gmane · 16m ago
I disagree with this interpretation of what I said. We HAVE evidence that time and gravity interact. It's actually more of a violation of Occam's Razor to suggest that time travel is somehow exempt from that interaction than to claim that yes, time travel should in someway be subject to the influence of gravity.
fyrn_ · 1h ago
1. Genetically superior
2. Tate Descendents
Pick One.
VincentEvans · 30m ago
Tall, powerful, beautifully bald, multitudinous and decease resistant!
dingnuts · 59m ago
Why are you giving Tate free advertising on a completely unrelated post? Just saying that asshole's name risks exposing more people to him.
Streisand Effect, people. If you hate someone and want them to go away you have to completely stop mentioning them online.
tempestn · 48m ago
Seems to me your comment has more of a Streisand Effect quality than the one you're replying to.
Arcorann · 1h ago
The 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.
gchamonlive · 1h ago
Maybe 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 · 50m ago
Wouldn't such a gate imply that an unlimited amount of entities would arrive at the time of the gate?
selcuka · 37m ago
Doesn'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.
Hatrix · 2h ago
Future people will have a Holodeck to simulate the past. No reason to actually go there.
JALTU · 2h ago
Or Hollywood!
modzu · 2h ago
is it real? of course not. expensive? very.
wyldfire · 41m ago
Time 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.
rhengles · 5m ago
Didn't we have flying birds before even the dinosaurs, let alone the Homo Sapiens ? So we had physical evidence that flight was possible.
Workaccount2 · 1h ago
I'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.
ryandvm · 49m ago
Yeah, 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 · 30m ago
It 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.
01HNNWZ0MV43FF · 1h ago
I loved that about the film Tenet. It's very grounded compared to say Terminator (not that I don't like Terminator)
JKCalhoun · 1h ago
"Primer" is arguably the best time travel film made/written.
thedrexster · 39m ago
this!!
Melatonic · 1h ago
Same
Dark Matter (the TV show) also does this very well (plus multiverses)
cogman10 · 54m ago
Could 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.
PaulHoule · 3h ago
Makes me think of this Asimov classic where you really can change the past
This 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 · 1h ago
It’s also possible the time traveling civilization was killed off by boiling the oceans to plagiarize the entire creative output of humanity.
rossdavidh · 1h ago
Submitted by Andrew Jackson, presumably the President of the United States of the same name.
jt2190 · 1h ago
Interesting:
> 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.
retrocog · 1h ago
Perhaps time doesn't objectively exist in the way it is understood as a premise of the paper?
gnabgib · 1h ago
Title: Where Are All The Tourists From 3025?
jmward01 · 1h ago
I have always thought that time travel is a solution to the fermi paradox.
mrandish · 1h ago
I've always suspected the reason is this century is just incredibly boring and literally nothing notable or even remotely interesting happens.
lazide · 1h ago
Eh, plenty of things to steal.
mrandish · 51m ago
Nah, everyone knows all the good stuff was before 1850 and after 2225. We're living in the 'fly-over country' of history.
Apocryphon · 2h ago
Looking 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
Finnucane · 3h ago
they’ve all gone 4025, where the real party is.
cwmoore · 55m ago
After 1000 years of recovering from the consequences of going back to 3024.
tocs3 · 3h ago
I was about to say: This is not the best time to visit right now. Mabey later.
modzu · 2h ago
time travel backwards is impossible. but there are undoubtedly time travelers from the past going forward in time
lordofgibbons · 2h ago
I've already been doing this for a while now ;)
xlbuttplug2 · 13m ago
Hope you remembered to get extra plutonium. It isn't available at every corner drugstore yet.
daedrdev · 1h ago
All you need is to go fast to travel forward in time
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.
This fact alone means that any time traveler is most likely to arrive in the middle of empty 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.
I am saying this trajectory calculation relative to current coordinates is impossible. Even modern satellites with super precise instruments still need regular ongoing “adjustments.” Time travel requires many order of magnitude more precision than satellite orbital maintenance.
In reality I'd bet neither are realistic, but that's what makes the stories interesting.
Of course the idea that your point of origin must be fixed from time A to time Z if you’re willing to allow for time travel is itself flawed. If you could somehow move an object to an arbitrary time you could move them to an arbitrary point in space, and your ability to calculate may be significantly greater on the grounds that you’d have more advanced technology than us. It’s all scifi woo though until someone actually time travels.
Pick One.
Streisand Effect, people. If you hate someone and want them to go away you have to completely stop mentioning them online.
> 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.
EDIT: If you created such rift and nobody would come out, then you'd have to start worrying.
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.
It's great for fiction, because of so many creative ways that you can structure your rules-violating-universe.
Dark Matter (the TV show) also does this very well (plus multiverses)
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.
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)
based on another Heinlein classic
https://en.wikipedia.org/wiki/%27%E2%80%94All_You_Zombies%E2...
where you can't because it's all just a knot.
No comments yet
> 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.