Time Paradox issue in Endgame (spoilers) question

This has been bothering me... I don't have anywhere else to ask this, and I figured most everyone had seen it by now.

Spoilers for Endgame ahead:

If Cap didn't go back to the present when he returned the stones and instead when back to marry Carter, then shouldn't Endgame's events have not occurred?

The Ancient One explained to Bruce that timelines split once there is a change. So, in the timeline of the MCU we watch, Cap would have been an old man when they went back in time to get the stones.

Obviously, he didn't do that since he gave up the Cap persona to live a married life.

So, if that's the case, he could have never gotten the mind stone from Hydra and would have never returned it to the present to defeat past Thanos.

Likewise, all the events in the MCU we watch involving Cap should not have happened.

This means the Thanos snap should be in full effect... right?

Comments

Patchie93

This has been bothering me... I don't have anywhere else to ask this, and I figured most everyone had seen it by now.

Spoilers for Endgame ahead:

If Cap didn't go back to the present when he returned the stones and instead when back to marry Carter, then shouldn't Endgame's events have not occurred?

The Ancient One explained to Bruce that timelines split once there is a change. So, in the timeline of the MCU we watch, Cap would have been an old man when they went back in time to get the stones.

Obviously, he didn't do that since he gave up the Cap persona to live a married life.

So, if that's the case, he could have never gotten the mind stone from Hydra and would have never returned it to the present to defeat past Thanos.

Likewise, all the events in the MCU we watch involving Cap should not have happened.

This means the Thanos snap should be in full effect... right?

No a split in the timeline doesn't mean that the current timeline disappears. Think of it as a tree each split is a new branch, that doesn't mean the the old branch or the trunk disappear when a new one is made.
If anything it opens up the idea of multiple realities and alternative time lines

Aryl

This has been bothering me... I don't have anywhere else to ask this, and I figured most everyone had seen it by now.

Spoilers for Endgame ahead:

If Cap didn't go back to the present when he returned the stones and instead when back to marry Carter, then shouldn't Endgame's events have not occurred?

The Ancient One explained to Bruce that timelines split once there is a change. So, in the timeline of the MCU we watch, Cap would have been an old man when they went back in time to get the stones.

Obviously, he didn't do that since he gave up the Cap persona to live a married life.

So, if that's the case, he could have never gotten the mind stone from Hydra and would have never returned it to the present to defeat past Thanos.

Likewise, all the events in the MCU we watch involving Cap should not have happened.

This means the Thanos snap should be in full effect... right?
No a split in the timeline doesn't mean that the current timeline disappears. Think of it as a tree each split is a new branch, that doesn't mean the the old branch or the trunk disappear when a new one is made.
If anything it opens up the idea of multiple realities and alternative time lines

No, I get that, but changing the events of the MCU we watch means that the end of Endgame isn't the MCU we watched in the past. We're now following a new MCU. An MCU were Cap was never present for any of the past events.

WardenZero

This is why I hated Endgame.
There.
I said it.
Fight me.

Warden out ~

DNA3000

If Cap didn't go back to the present when he returned the stones and instead when back to marry Carter, then shouldn't Endgame's events have not occurred?

The short answer is neither the screen writers nor the directors thought this through carefully, so there's no definitive answer in the movie. They even disagree over the technical details of what happened, so there's really no perfect answer.

My own theory makes some presumptions. First, when they were setting up the time portal, they didn't all just happen to miss seeing the old guy sitting there. So Old Steve was not there sitting on the bench before he went back to return the stones.

This means, more or less as the characters in the movie state Cap must have gone back into a different timeline, one that diverged from the one that encompasses the main events of the movie outside of time travel. Supposedly once he returns the stones, those alternate timelines should "reconnect" to the main timeline, in effect causing them to cease to exist.

But while Cap possesses Infinity Stones, as the Ancient One says they create the perception of time: Cap is in an alternate timeline which the stones force into existence, because they are what makes existence. As he puts the stones back, the timeline that split where that stone leaves then reconnects back to the main timeline.

He then uses the time-space GPS to go back to the 1940s to be with Peggy Carter. At this point he doesn't have any Infinity Stones, but he still has to be in an alternate timeline because the laws of physics in the Marvel Universe, according to all the knowledgeable people in it, says you can't change your own past. All of the events in the "future" beyond 1940 are still in Steve's past, so they can't be changed relative to his perspective. Instead, they have to change in an alternate timeline. But every moment after he enters the time portal is *not* in his past, so it is at that moment that his timeline can "reconnect" to the main timeline, and that's when Old Steve appears on the bench. He was sitting on that bench in the past, but the Hulk and Falcon and Winter Soldier can't see him until his timeline "overtakes" his past up to the point he entered the time portal.

Incidentally, when characters like Professor Hulk say that you can't change your own past, most people have interpreted that to mean it is impossible to even try, because while you are in the past you create an alternate reality. But that isn't necessarily true. They may be referring to a variation on the predestination paradox. In effect, it says that for causality in the universe to be consistent, any change you make in the past must be something that actually already happened: you cannot make a change you'd actually see. In particular, you can't make a change that alters whether or not you go into the past, because that would create a contradiction. So many what Professor Hulk was trying to say is they couldn't go back into the past and kill Thanos because doing so would create a situation where they wouldn't bother to go back into the past, because no Thanos. This would create a causality contradiction, with the universe wouldn't allow.

So basically, Steve has to return to the main timeline because he doesn't possess the Infinity Stones any more, and they are the things that create existence. But until his clock catches up with when he originally went into the past the universe "cocoons him" in an alternate reality to protect itself from causality paradoxed. Once he arrives back in 2024, he pops out of that protective alternate timeline and into the main timeline.

Fred_Joeity

Or you can stop trying to find logic in time travel. I just assumed he had come back from an alternate timeline, and the “old man sitting on a bench” thing was just for dramatic effect

DNA3000

It might seem weird to think about the universe "fixing" things, but there's actually a thought experiment that suggests it can, in some situations, without resorting to some higher power controlling the universe. Imagine a single particle moving in a straight line. We build a time machine and position the machine so the particle just happens to enter it. We send it back in time to a minute in the past, and aim it at its past self. The particle exits the time portal in the past, continues flying in a straight line, and hits itself in the past.

This causes the particle to change direction. So one minute later it misses the time machine. So it doesn't go into the past. So nothing hits it in the past. So it flies into the time machine, going back into the past and hitting itself, knocking itself off course and missing the time machine. This is a contradiction. So what actually happens next?

Well, quantum mechanics says we cannot know perfectly how fast and in precisely what direction that particle is moving. We have to guess, within the limits of the uncertainty principle. So we can't actually know, when the particle goes into the past, how it will hit its older self. There are a lot of possibilities.

Except there's a principle in quantum mechanics that says particles do whatever is not impossible. If an option is impossible, the particle doesn't do it. That seems obvious, but now think about that particle. If the particle hits its older self and completely knocks it off course, that leads to a contradiction. That means that path is impossible. So it *cannot* happen according to quantum mechanics.

However, there is at least one path that is possible. Imagine the particle goes dead center into our time machine and exits on a direct collision course with its past self, but because of the uncertainty principle it glances off instead of hitting it square. This causes it to only slightly change direction. It then enters the time machine not dead center, but slightly off center. This causes it to exit in the past, and not be aimed directly at its past self. Because the aim is off, instead of hitting it dead center it just glances off.

This is a consistent version of reality. We try to capture a particle and shoot it at its past self, but because what we want to do leads to a contradiction and is impossible, quantum mechanics makes something happen instead that actually creates no contradictions. And it happens simply by virtue of the mathematics of quantum mechanics.

With a bit of narrative exaggeration, this can explain some of the mechanics of time travel the Marvel writers were trying to use.

DNA3000

Or you can stop trying to find logic in time travel.

Well, first, there's no fun in that.

Second, only things that have rules can have narrative power. Anything that doesn't honor rules cannot have any dramatic effect in a story, because the audience cannot expect anything and cannot anticipate anything. We're given enough information about time travel for the audience to understand the limited effects of the important aspects of what's going on. It has to have enough logic for its own story, and I think it basically does. But there's no harm in wondering how much farther the ideas can go.

All science fiction, at least all good science fiction, is based on one question: what if. Given all of this, what set of that logically follows. There's a reason the umbrella term for works of this kind is "speculative fiction." They are supposed to engage in, and invite, speculation.

LordRaymond3

Simple answer: That's not how time travel works in the MCU

Species11

This has been bothering me... I don't have anywhere else to ask this, and I figured most everyone had seen it by now.

Spoilers for Endgame ahead:

If Cap didn't go back to the present when he returned the stones and instead when back to marry Carter, then shouldn't Endgame's events have not occurred?

Likewise, all the events in the MCU we watch involving Cap should not have happened.

This means the Thanos snap should be in full effect... right?

Well a simple and maybe more profound answer might be, maybe Cap was supposed to go back to the past in the MCU timeline all along?

My prediction is that the MCU will mostly avoid the multi-alternate timeline thing, because it’s a really cheesy plot device and sucks the drama out of everything when there’s an infinite supply of variations. Further, I don’t want to have to do that much sorting at the movies. Goatee Bucky, Scuba Bucky, Bucky the Dog... *snore*.

The Skrull / Secret War has the same screen adaptation problem, when everyone could be an imposter, will get old quick. In my mind Marvel tied off both into Far From Home, and will be moving on.

Jaded

Whenever I see/read/hear the word causality, I think of the Matrix...🤷‍♂️

Sundance_2099

remember the MST3K mantra. It's only a movie, I should relax and enjoy it.

Fred_Joeity

Or you can stop trying to find logic in time travel.
Well, first, there's no fun in that.

Second, only things that have rules can have narrative power. Anything that doesn't honor rules cannot have any dramatic effect in a story, because the audience cannot expect anything and cannot anticipate anything. We're given enough information about time travel for the audience to understand the limited effects of the important aspects of what's going on. It has to have enough logic for its own story, and I think it basically does. But there's no harm in wondering how much farther the ideas can go.

All science fiction, at least all good science fiction, is based on one question: what if. Given all of this, what set of that logically follows. There's a reason the umbrella term for works of this kind is "speculative fiction." They are supposed to engage in, and invite, speculation.

Personally, I just dislike it when people try and find “logical fallacies” in sci fi movies (as in more than just for fun, and actually thinking its horrible because it “doesn’t make sense”), so I tend to take most at face value. If there’s a somewhat logical explanation, I’ll take it, but otherwise I’m not going to put too much effort into logical acrobatics

Nojokejaym

Maybe he returned everything to its timeline then returned the stone to Peggy timeline last and stayed there