Some ideas are:
- You branch off into another timeline and your actions make no difference to the previous timeline
- You’ve already taken said actions but just didn’t know about it so nothing changes
- Actions taken can have an effect (so you could suddenly erase yourself if you killed your parents)
- Only “nexus” or fixed events really matter, the timeline will sort itself out for minor changes
- something else entirely
You’ve already taken said actions but just didn’t know about it so nothing changes
12 Monkeys did this one perfectly.
You can’t change things because if you undid the thing, then there wouldn’t be a reason to undo the thing. If you go back in time, you are just going to do what you already did because that is in the past.
I’d totally forgotten about 12 monkeys. I had that VHS of this when I was 11 or 12 years old, I probably watched it 30 times and I never fully understood it. 25 years later I think it’s time for me to rewatch this
Rewatched it recently, it held up really well!
Logically speaking it’s the only way time travel can be done, and for bonus points physics wouldn’t have a problem with it.
Any Back to the Future shenanigans is just creating alternate realities, which may or may not instantly destroy the original.
“Default behaviors is undo, no redo. You control undo the undo. Emacs.”
Oh, I’ll have to watch that
Whichever one is objectively correct based on empirical evidence.
Fun fact: time travel does exist, and I am myself a time traveler. The fact that I’m travelling at one second per second along with everyone else is just a minor detail.
Imagine if someone just naturally traveled through time at like… 1.0005 seconds per second… What would that look like? Would we be able to tell? Would they be able to tell? Would their perception be different?
This is a Relativity thing, isn’t it? Like the astronaut twins sort of…
That’s exactly like being a bit closer to the bottom of a steep gravity well.
Yes, we could tell if they took a precise clock with them. In fact, we have to account for an even smaller discrepancy in order for GPS to work: we here stuck further down in Earth’s gravity well travel through time and extra ten milliseconds or so per year vs. an orbiting satellite.
Are we traveling through time? Or is time simply a universal constant of entropy? Everything you experience is energy flowing from a higher potential to a lower potential, with some “loss” to heat. Without that downward shuffle, a rock balanced on it’s tip is indistinguishable from a time-stopped version of itself.
Basically, time is your body’s sensation of the inevitable terror that is the heatdeath of the universe.
Why would it be less terrifying to be further away from a gravity well?
I think you meant this comment for a different thread.
Nope.
Okay. What did I say about gravity wells?
You implied that life would be more terrifying the faster you traveled through time, like what would happen at the bottom of a gravity well.
Where?
Its a one way trip. You can never go back to the original universe.
I have always been a fan of stable time loops so I guess option 2 is the best one for me.
One trope I’d like to see more of is loops which are not stable themselves, but are stable as a group. Eg a 2-loop has loop A in which someone goes back in time and changes history leading to a new timeline loop B. Someone in loop B later goes back in time and changes history in a way that turns the timeline back into loop A.
My headcanon is that your option 3 is basically an n-loop that we only see the first few loops of.
I really like the nothing is changeable and travel is possible and anything you do while traveling has already happened / was already going to happen concept
Primer because Primer. (Video warning and some spoilers for a bunch of different films.)
I don’t know if I would subscribe to it, but it is one of the more interesting ideas for time travel.
Primer spoilers, kinda, xkcd style:
From a quantum perspective the Deutschian and similar models are honestly pretty compelling. They essentially require matching up the past and present in a consistent way that can remove paradoxes.
These make the most sense because it’s entirely possible to write down spacetimes that contain “closed time like curves” (CTCs) ie. paths connecting past and present and you can then just let physics play out on these models (or more commonly using black box quantum circuits). The only consistent way to do it is to make sure the past and future side of such curves agree. It’s not my area at all, just something colleagues of mine did, but from memory there are nice approaches using the path integral formalism that work really nicely in these scenarios.
All that’s to say that I don’t think time travel leads to anything changing, the past will have always agreed with whatever time travel happens in the future.
Having worked very briefly with the spacetimes that produce CTCs, I don’t expect we’ll be able to time travel because they usually violate the weak energy condition.
https://en.m.wikipedia.org/wiki/Quantum_mechanics_of_time_travel
- You branch off into another timeline and your actions make no difference to the previous timeline
New actions, new consequences.
This. Time traveling is a purely selfish endeavour.
Go back and kill Hitler? Congratulations! Only you understand what changed. Doesn’t help the 7 billion people you left in your original timeline.
But you now get to live in a cool alternate reality where the soviet union clashed directly with the allied forces as the axis never existed.
. . .
Kirov reporting.
The past, present, and future do not exist as separate states.
Imagine a vast array of all possible states of matter in the universe. Imagine reality has a finite spacial resolution. With a series of numbers, or even a single very large number, you could provide a unique identifier for every possible arrangement of matter in the universe. The positions of every star and galaxy. The detailed interactions of every quark. Imagine a list or array that would have a number of entries equal to some indecent multiple of “ten to the ten to the ten…” Imagine all these possible states, every possible configuration the matter of the universe could occupy.
Then realize…All of these possible states exist at once. They are all as real as any other. There is no preferred state. They all exist in some vast “10 to the ten to the ten” dimensional spacetime. What we perceive as the flow of time is simply us moving from one of these states to another. But our consciousness cannot move arbitrarily between states. There are elaborate rules on which states you will be able to observe dependent upon the states you previously observed. We call these rules the laws of physics.
So when you travel through time, you are simply altering your path on this vast multiverse of possible realities. There is no “real” reality. They are all real. Every possible configuration of the matter and energies of the universe physically exist concurrently.
There are no timelines to split or erase, because there are no timelines. There are just conscious minds moving through a near-infinite array of possible “nows.” And all of the nows exist simultaneously. There is no real one. From the perspective of a “time traveler,” it will seem like they changed “the future.” But the truth is the very idea of a past, present, and future as distinct entities is madness. We’re just consciousness drifting through the continuum, from one of the near-infinite nows to another.
That’s a really long way to say “the first one”.
I like the persistent present. We simply live with the paradoxes.
“Remember when Hitler was assassinated in 1919, 1933, 1936, and 1939, then off’d himself in his bunker in '45?”
I don’t need anymore subscriptions, thank you.
Time travel does exist, but you can only go forward. You just need to approach the speed of light relative to a frame of reference, and you will travel a shorter time span compared to it.
My personal favorite?
Space and time is an infinite number of parallel realities that constantly compress and unravel at every possible random chance. We are 4th (or 3.5th) dimensional beings that experience the most probable result aggregated from an infinite existence. If you time travel back in time, and change the past, it would not affect the your past, but it would affect your future, if you time traveled back to your current time.
I subscribe to multiverse theory. It’s probably the safest route and probably most likely.
I believe it’s impossible in the real universe.
Sure there are solutions of general relativity that contain time loops, but they require stuff like an infinitely long cylinder, or escaping a spinning black hole, or negative energy. I just don’t believe beings made of finite matter and with finite energy will ever be able to time travel (except into the future at various rates) and that’s the only kind of beings I think exist.
The only saving grace of GR based time travel is that we don’t actually know if the weak energy condition is physical. It probably is, but technically it could be a false assumption.
Yeah, but I feel like if it were feasible to violate the condition we would have done it by now (besides the Casimir effect). That’s just an opinion of course, and I’m just an interested layperson, but I know physicists have been trying for at least a few decades.
But my question was if it was possible. Not do you believe it’s possible.
You’re right.
It would have to be multiple timelines or single consistent history. Of the two, I think multiple timelines is a little more likely.
You are currently correct. Things change.
