LogFAQs > #963071372

captpackrat posted...

The time travelers are always stupid about it. They run around trying to warn people about what's about to happen or they try to prevent it. And they never think about how they'd be changing history if they stop some disaster.

There's plenty of fiction that doesn't do that, though. Where the main characters are like "we have to be careful not to change the past or we'll erase our own future!" And then the emotional conflict of the story becomes whether or not you can resist the temptation to stop bad things from happening to good people simply because you know they're supposed to happen. Or just the mechanical effects of trying to "fix" the past back into its original shape if you've already accidentally broken it (like Back to the Future).

There's also the type that falls somewhere in-between, where the protagonists will find a way to change the past, but do it in such a way that it seems like the past remains unchanged. Like saving the life of someone who is historically recorded to die at such-and-such a point in such-and-such a way, but you just fake their death instead and they go into hiding. Or exploiting the Observer Principle (ie, you know someone dies because you read a newspaper article from the era - but it turns out after you save the person's life you just ask the newspaper reporter to file a false story).

And all of this is complicated by variations over whether or not time is elastic (the past can be changed, and likely even relatively small changes can completely alter the future), plastic (the past can be changed, but history has inertia and will generally fall back into the same patterns unless you're making huge changes), or immutable (where you literally cannot change the past at all, because any action you take is either something you already did, because you were always part of the past, or because anything you do in an attempt to alter a major event will fail as the universe itself is seemingly acting to prevent you).



Revelation34 posted...

It would be interesting if we had one where they actually succeed.

There's quite a few, honestly.

Related to what I said above, there are stories where time travelers change the past but it gets covered up so the future doesn't actually change, stories where the past is changed and the future is radically changed (and the time traveler either ceases to exist, loses the ability to go home, or returns home to see a completely different world), stories where the past is changed but only in a minor way that only the main characters are aware or, or even stories where even the slightest change immediately fractures the timeline so any changes you make don't actually alter your own future at all, but create an entirely new world (and travel back to the future either takes you back to your original timeline, fast-forwards you on the new timeline, or becomes impossible because you can no longer access your original timeline by going "forward" - you'd essentially have to travel back to your point of divergence and then double back down the "right" timeline).

Time travel physics can get confusing. And since they're all mostly hypothetical anyway, they tend to differ across different stories, and most of the details get handwaved away as not being all that important.



JimBeamMeUp posted...

My problem with time travel is it never accounts for the movement of the earth, the solar system, or the galactic plane. The Delorian would hit 88.8mph and more than likely *bamf* in another time out in the cold vacuum of space...and that's not even accounting for conservation of angular momentum.

Most sci-fi stories assume those mechanics are built into the device you're using to travel, presumably anchoring you to a specific point in spacetime and then projecting that point forward or backward in time, and simultaneously sideways in space. Or are based around wormhole physics where the ends of the wormhole are physically stationary in some way and compensate for spacial movement. It usually gets glossed over because it's rarely important and most of the audience won't understand or care anyway.

Most fantasy time travel stories simply don't give a shit, because a wizard did it, and you should probably go outside more.



Mensis posted...

in endgame how did captain America come back as an old man? Hulk says they cant go back and change the past earlier so wtf? He should have just disappeared from their timeline entirely

The writers and director actually disagree about this.

One of them (I forget which) says that because he went back and changed minor things and wasn't obvious about it it "didn't count", so the timeline didn't split. He's basically been hiding out until time caught up with the point where he left, so he could show up at the meeting. He's been in our timeline the whole time.

The other says the timeline absolutely split, so basically Cap spent most of his life in an alternate universe, shacked up with an alternate universe Peggy, and then only returned to "our" timeline after she died, so he could close the loop and pass along the shield.

Personally, I tend to favor the latter theory, but some people don't like it because it implies he was cool hooking up with someone who wasn't "his" Peggy and letting the alternate universe version of himself stay on ice for decades when he could easily have told people he was still alive and where to look.

So it's ambiguous enough for the audience to make up their own mind.



DrPrimemaster posted...

I read some story about some lady who traveled back in time to see the Titanic and ended up messing up her leave time and ended up dying on it.

It made me really sad, I still think about her.

Could be worse. Could be like the love interest character from the second season of Heroes, who wound up getting sent to a dark future, before said future was retroactively prevented and erased, which theoretically implies she ceased to exist as well.

Though the idea of people from the present traveling back to the past and falling in love with people from the past only to die in a famous disaster of some kind is pretty common in time travel stories. With about a 50-50 chance of the traveler bringing the love interest to the future with them instead, thus saving them from their own fate (after all, if you're on the passenger list of the Titanic when the ship goes down, and you're not among the survivors they rescue, everyone's going to assume you died... but maybe you're just living off the grid or under a fake identity in 2012).