Spoilers, obviously. And also blah blah blah nerd nerd nerd geek geek geek.
Time travel plays a big part in Avengers: Endgame, and as is often true, where time travel goes, confusion follows. This is true in spite of the movie’s efforts to make its time travel rules as clear as possible.
They say, first of all, that traveling to the past and doing stuff doesn’t alter your own personal past. Instead, it creates an alternate dimension or timeline that moves forward from there, with new events playing out in a new way. Specifically, this happens when an Infinity Stone is removed from the timeline (or to put it another way, when all six stones aren’t in existence at the same time), because it’s the Infinity Stones themselves that keep time moving forward as a linear, understandable experience.
(Actually, recent media interviews have shown that the movie’s director and writers don’t necessarily agree whether an alternate timeline is created by the simple act of time travel itself, or only when an Infinity Stone is removed from the timeline. This just goes to show how unsettled all these concepts are, at least until future stories confirm things one way or the other.)
Anyway, when the Ancient One objects to creating a new timeline (which she will be living in) where Infinity Stones are missing, Bruce Banner comes up with a solution: after the heroes’ victory, they will return the Stones to the moment they were taken, so no new timeline is actually created. It’s actually kind of uncreated, according to the way he visualizes it. But is Bruce actually right? He’s a smart guy, but he couldn’t even think of reprogramming Vision’s synapses to work connectively. Does he really know that much about time travel and alternate universes?
Note that the Ancient One doesn’t necessarily confirm this hypothesis (being more focused on Stephen Strange’s unusual behavior) but she seems to tacitly agree.
Is this what goes on to happen in the movie?
Is it instead that these alternate universes just continue to exist, hopefully with all the Infinity Stones in location so reality doesn’t just disintegrate around everybody? That’s how some of the articles and comments that I have read have treated it.
But, if that’s the case, those universes are still kind of messed up, at least for the most part. Let’s consider what they are all like, even if Steve Rogers was successful and somehow returned the Infinity Stones at the exact point of their removal.
(But first, a quick digression: “exact point of their removal” is dubious, otherwise you’d think most of the heroes would have noticed Captain America sneaking around nearby them in the earlier sequences. But, it doesn’t seem critical that the Stones returned to the exact same place that they were removed from, just that they are present in the same reality. In that case Steve could have brought them back to their specific locations at more convenient times.)
2012 – Alternate Timeline #1
In this universe, even if future-Steve returns the Time Stone to the Ancient One and the Mind Stone (in Loki’s scepter, into the hands of Hydra-controlled SHIELD), there are lots and lots of changes to the timeline.
• Loki escapes custody, with the Tessaract (Space Stone) in tow. That means he’s not in position for the events of Thor: The Dark World, so who knows how that all works out. Does Malkeith destroy Asgard and get the Aether? I can’t remember how everything transpires in that movie.
• Captain America believes he’s been beaten up by Loki, disguised as himself
• A bunch of Hydra agents, including Agent Sitwell, believe that Captain American is a Hydra agent too. Probably, they will soon discover they are wrong and then they’ll think that Captain America is “onto” them. The only thing that will save Cap’s life at that point is that they may also come to believe that this was also the doing of Loki…but they are likely to get suspicious when the Mind Stone is abruptly returned to them! So Cap’s future is probably in peril.
• The Ancient One gets some spoilers about the future of the MCU and Infinity War in particular. But then given all the other changes these might prove useless, which means she’ll have no bragging rights on the internet forum she frequents.
Incidentally, I realize that technically, this isn’t the movie’s first Alternate Timeline. That was created when Clint Barton revisited his family sometime before the Snap. But I think we can safely slot that into whatever theory we adopt without really discussing it, as his actually interference was so negligible that it could easily have gone unnoticed.
2013 – Alternate Timeline #2
In this universe, Thor and Rocket visit Asgard to steal the Reality Stone from within Jane Foster. These is the least changed universe, as all that really happens (assuming Mjolnir is returned at the same time as the Stone) is that Frigga gets a visit from the future-version of her son. She seems pretty resigned to the fact that she might be in for tragic fate, so there doesn’t seem to be a great risk of any lasting changes.
2014 – Alternate Timeline #3
Here, Nebula and War Machine attempt to retrieve the Power Stone before Peter Quill finds it at the start of Guardians of the Galaxy, while Black Widow and Hawkeye head off to Volmir to retrieve the Soul Stone from its guardian, the Red Skull. Presumably, the activities of Clint and Natasha would not have a lasting effect on the future, but all the business with Nebula and Rhodey definitely does.
• Peter Quill is knocked unconscious before he finds the Power Stone.
• Thanos, Nebula and Gamora of 2014 find out about the events of Infinity War and the first half of Endgame, and make efforts to change them.
• Nebula replaces her future self, goes to 2018, does some jiggery-pokery with the time machine and brings Thanos and his entire armada to this time period.
• So actually, Thanos and his whole army disappear from time for about four years, including over the events of Guardians the Galaxy volumes one and two. Gamora and Nebula never participate in these events, changing pretty much everything. Thanos never does any of the events of Infinity War either, since he died in the future!
• Except that after Cap returned the Power Stone, it should have been picked up by Korath the Pursuer, who was right behind Peter Quill in the original timeline, so Thanos probably should have had the Power Stone when he made his Endgame attack. Which would mean…two Power Stones existing side by side (theoretically possible, given the two Nebulas, maybe?), and would probably mean he’d have easily won the battle.
• Even if Thanos’ time travel were somehow undone by future-Cap’s actions, the timeline is still in trouble as Thanos has that Power Stone much earlier than he did before.
1970 – Alternate Timeline #4
I deal with this one last, as it was shown last, even though it’s linearly first. In this new reality, Captain America and Iron Man visit 1970 to steal the Tesseract and also a couple of Pym Particles. The changes here appear smaller than some of the others.
• Howard Stark talks to an odd guy named Howard Potts, and gets a hug from him.
• Hank Pym gets a prank phone call that takes him away from his office.
• A couple of Hank’s Pym Particles go missing. Hopefully he can just make up some more.
• A possible intruder alarm is registered at SHIELD and investigated, but nothing ever comes of it.
???? – Alternate Timeline #5
By this, we’re now referring to the timeline that Steve created when he was reunited with Peggy. Of course, it’s possible that this is the same as the 1970 timeline–Peggy did look pretty similarly in that dancing scene to how she looked in the 1970 sequence (which is to say, pretty amazing for a woman who is supposed to be more than 35 years older than she was in First Avenger.)
Either way, for convenience, let’s assume that Steve doesn’t reunite with her until after she is married and has children, and her husband has died a tragic but completely natural death. We can only guess how Steve conducted himself at this point, but if he understood that he was in a completely unique timeline (albeit, one that was safe with all the Infinity Stones in it) than presumably he’d have been pretty open and public about things. He probably managed to root out Hydra from within SHIELD before they got very far, saved Bucky much earlier, and maybe even prevented the original Wasp’s disappearance. Villains like Darren Cross, Aldrich Killian and Alexander Pierce could all have been stopped before they got anywhere. He could have anticipated Loki’s attack and done something to stop it, and prevented the rise of Ultron. He may have tried to somehow anticipate Thanos and stop him as well.
Who knows what he’d have done about the other Steve Rogers who was buried under the ice somewhere, but given that he bequeaths his shield to Prime-Universe Sam Wilson, he doesn’t appear to be grooming him to be his replacement. Or, given that he knows about Wakanda and the literal mountain of vibranium present there, maybe he just had some extra shields made up.
Ultimately, after he got old, he found some way of traveling back to the Prime Universe (he could have been lurking around there for any amount of time) for his meet up with Sam at the end of the movie.
Does this sound right? It doesn’t, does it? If this is how we’re meant to interpret things, then it really takes away from the story. The Avengers, rather than being heroes, just seem like giant jerks half th etime. In many cases they’ve left the other timelines worse off, and certainly they’ve left them a mess.
Is there another way we can look at all this, without assuming that each visit to the past not only created a new timeline but also left them all in a jumble of chaos?
Well, clearly we’re not meant to look at time travel as changing history. They go out of their way to point that out, several times. And the evidence backs it up–future-Nebula doesn’t disappear when she kills past-Nebula, the original “snap” isn’t undone by the death of pre-snap Thanos, etc.
So, to deal with this, I’d like to revisit what Bruce Banner suggests to Ancient One: that if they return the Infinity Stones to their proper time and place, that the new timeline that was being created is effectively undone. The Stones are not ordinary artifacts, after all. Indeed, the Ancient One tells us that they are what basically is keeping time running forward. We can even theorize that all the time travel in the film is only possible because the Avengers are living in a world where the Infinity Stones no longer exist. So when a Stone is returned to existence in 2012 (or 2013, 2014, or 1970), the renewed presence of all six causes time to be restored–the original timeline which the Infinity Stones were keeping chugging along in the first place, setting everything right, even removing the events that led up to the Stone being removed. So now, our restored timelines have no “memory” of any of the changes–Frigga’s peptalk to her son, Hank Pym’s prank phone call, Peter Quill being knocked unconscious, or even the Ancient One’s consultation with Bruce.
Our heroes still remember those events, though. Returning the Stones does not remove those events from the subjective experience of the time travelers, because they still experienced them in those branching timelines. But if they could somehow objectively look back at those moments, they’d find no evidence that any of it actually happened.
This has the convenient effect of removing all of the narrative problems mentioned above. But it does, I’m sure you’ve noticed, bring up a whole bunch of new ones.
Problem Number One: Loki
Loki wouldn’t actually be a problem except that he’s apparently getting his own Disney+ TV show pretty soon. We’re all guessing that Loki’s escape from the revised 2012 setting, along with the Space Stone, is going to be used to explain how he’s appearing in this TV show in spite of dying in Infinity War. If we adopt my “returning the stones undoes the the entirety of the new timelines” theory, then how will that work?
I’d suggest simply chalking it up to Loki’s power as an Asgardian, coupled by his possessing that timeline’s version of the Space Stone. Reveal that he was able to get to some distant realm where, with his great power, he was able to retain his existence even when reality changed back to normal without him. Maybe he’s even stuck in this other realm until the “Prime Loki” dies in Infinity War, explaining what he’s been doing while the rest of the MCU was carrying on.
Problem Number Two: Thanos
So, just to be clear, are we saying that the 2014 Thanos that attacked earth at the climax of Endgame was from a branching timeline that no longer existed after Captain America returned the Stones?
That’s right, we are. And just like the heroes remember their visits to the other timelines, they also remember–and indeed experienced–an invasion from one of those timelines into their own.
Problem Number Three: Gamora
This leads us to Gamora, who was from that 2014 timeline, and who alone out of the 2014 invaders was presumably not killed when Iron Man used the Infinity Gauntlet. Instead, when her branching timeline was wiped out behind her, she was effectively “cut off” and “stranded” in her future, or the present of the MCU. I don’t have any evidence of this except for the tease at the end of the film that Quill is wondering what happened to her, and presumably Zoe Saldana will appear again in the next Guardians of the Galaxy film. This would be the perfect way to do it, and it’d give them some new character arcs to play.
Problem Number Four: Captain America
This, I admit, is the biggest problem–my only theory is born from not wanting to sully the characters in some way, but this part of it kind of does to some degree.
My general thought is that when Steve Rogers returned to Peggy–presumably in 1970 or again, at some point after she’d had her children–he just kept a very low profile, and allowed events to play out as they had, thus not creating a new timeline at all. Of course, the difficulty is that it’s hard to imagine him not interfering in the infiltration of SHIELD or the abuse of Bucky or the attack of Ultron…
But maybe he felt deeply convicted about the need to not try to change things, knowing that’d he cause all sorts of timeline problems if he did, and that things generally worked out anyway, ultimately. This could even tie into the idea of him learning to enjoy life…in this case by being willing to not take upon himself the need to always be fighting for his ideals.
Presumably he kept himself hidden when his younger self visited the aging Peggy–but it may not have been too hard, as it doesn’t seem like Steve saw her all that often after emerging from the ice. Older Steve would probably have avoided hanging out much with Peggy’s niece Sharon, because that would have just been weird. And probably Older Steve would have been dusted in the Snap–you’d assume that if 50% of all life was going to be eliminated, that’d include 50% of the Steve Rogers as well.
But…where did Older Steve get his shield (the one he gave to Sam) if not from an alternate timeline?
Maybe he traveled to Wakanda in the 1970’s, made friends with King T’Chaka, and managed to get some vibranium to put one together secretly. I know, we’re really in crazy theory time, but surely we can agree there would have been someway to get a shield created in all those decades. I mean, we may not like the theory, but surely that’s not going to be the thing that breaks it for us, right?
So, to sum all this up, I prefer this idea (that the returning of the Stones “heals” the timeline fracturing) because it makes the story smoother and it keeps the characters more consistent. I don’t know that there’s direct evidence for it in the movie itself, but to my thinking it’s consistent with the tone that the movie is striking–we’re clearly not meant to look at middle of the film’s time travel quest as some sort of broad-scale destructive process. So the idea that any alternate timelines are ultimately folded back into the Infinity Stone-guided reality is quite satisfactory to me, whether those timelines were created by the Stones’ remove or simply by the act of time travel itself.