LogFAQs > #963071979

Notschmendrake posted...

Its nonsense as well. You never would have gone back in the first place to cause whatever is making you go back every other time.

Depends on how time travel and the past works.

In a chrono-stable universe, the past cannot be changed. Anything that happens has always happened and will always happen. You were always the one that made that person disappear, and your going back to investigate was always the thing that caused it to happen in the first place. It's a simple stable closed time loop. Basically, it boils down to us trying to understand four-dimensional reality with a three-dimensional brain. It makes perfect sense even if we have a hard time understanding it (because honestly, we have a hard time understanding a lot of things).

Conversely, in a universe where time can be changed, there would have been an original inciting event without you (say, the missing person falls down a ravine and no one ever finds the body), but your actions in the past change events, and you essentially create a closed time loop (wherein you make the person disappear, which in turn becomes the impetus for you to go back in time in the first place). You have altered history, but from the perspective of outsiders nothing has changed, and future iterations of the time loop will seem like they've always been how things work (ie, there'll be no evidence left of the original timeline).

The latter is actually the easiest solution to potentially change the past in universes where altering the past seems impossible. It was my immediate thought while watching the Time Machine remake with Guy Pearce (spoilers):

Guy Pearce invents a time machine to go back in time and save his fiance who died. But every time he saves her she's pretty much immediately killed in a different way, as it seems like the universe is twisting fate to guarantee she winds up dead. He eventually realizes she cannot be saved, because it was her death that motivated him to build the time machine, so if she doesn't die, he won't invent the time machine, which means he won't be able to use it to save her. So it creates a universe-shredding paradox, and reality itself will always manipulate events to stop him from saving her to protect itself. So he has to learn to accept her death and move on.

Meanwhile, my immediate reaction was "So go back, fake her death, then either hide her or bring her forward in time so your past self thinks she's dead, thus inventing the time machine, thus preserving the loop. Stop being a wuss and letting the universe boss you around - you're supposed to be a genius!"

Again, the problem is that a lot of this is all hypothetical - we really have no idea how time travel would work, if it's even possible at all. So we're mostly just making shit up.

(And the real problem with time loops is uncreated eternal artifacts - if I travel back in time, and give myself an object, and I keep that object for years before eventually going back in time and giving myself in the past that object, -I- have completed a closed loop, but the object itself is trapped in an infinite and never-ending loop, wherein it has no origin and no end, and somehow defies the effects of entropy, never breaking down or changing over time.)



SKARDAVNELNATE posted...

I often question how things like that are supposedly connected in time travel stories. Like while in the past the main character alerts someone that their shoe is untied. Then upon getting back to the present they learn a race of sea creatures have overrun California. What is the sequence of events that lead from the one thing to the other?

It's assuming that time is very elastic.

Realistically, the moment you appear in the past you have irrevocably altered the timeline. Each breath you draw is moving molecules in ways they didn't move in the original timeline. Every move you make is displacing matter and energy in ways that are different from their original patterns. Each molecule and particle moves, displacing others, setting off chain reactions that never happened in the original history. Even if you never even speak to another human, you have already left a massive ripple in the water.

And once you throw human interactions into the mix, things get even worse. A 30 second conversation you have with someone slows them down by 30 seconds - which may be the difference between whether or not they get stopped at a red light on the road later. Which in turn may lead to them either meeting or failing to meet someone. Meanwhile, them being in different places means they can slow or avoid other people, who's own behavior is likewise changed. As the snowball of changes slowly spreads and becomes an avalanche, major changes can occur (like in the mostly forgotten movie Sliding Doors, where the difference between missing or catching her train is the difference between the main character either discovering her boyfriend is cheating on her or not, which radically changes her entire life).

Actual conversations can alter things even more - flirt with a waitress and it might change how she feels about her boyfriend, causing (or preventing) a break-up. Pissing someone off might cause them to take out their frustration on someone else, causing a fight that never happened before you changed things. History is made up of a million billion variables constantly interacting, and you've just thrown a bowling ball into a pinball machine. Over a long enough span of time, the constantly rippling changes may lead to radical differences - people living different lives, entire cultures taking different paths, wars being fought (or not fought).

In settings that are relatively chrono-plastic, this doesn't matter - whatever changes you make are smoothed out almost immediately, and almost nothing beyond what you specifically do matters. But in realities where time is both elastic and volatile, even the slightest change in the past can potentially lead to a world ruled by Nazi dinosaurs.



SKARDAVNELNATE posted...

Also, they would have created a bunch of other timelines where one or more of the infinity stones vanished since even after returning them it wasn't to the same timeline it was taken from. So there wouldn't have been a "snap" for them to undo.

Not really. The Ancient One basically says the real problem isn't that they need to undo the snap, but that simply removing one stone from a universe creates an imbalances of forces that will eventually destroy the entire universe. Which is why she's adamant that they can't have her stone (at first), or that they need to return her stone to the exact point they took it from if they do.

The implication is that bringing the stones back to the exact point you took them from doesn't create yet another alternate timeline, but is just preserving the original timeline, and preventing them from suffering cosmic decay once the stones are gone.

But yes, it does imply that if they screwed up their timing, they just destroyed multiple parallel universes.

It also raises the question of whether or not having ALL SIX STONES in our universe destroyed simultaneously has a much more significant side-effect than anything we see. Though that might be a moot point since Doctor Strange went on to break all of time and space anyway.