How does time travel work in Avengers: Endgame? The Marvel timeline explained
1 May 2019, 14:10 | Updated: 1 May 2019, 14:20
Time travel is integral to the Avengers: Endgame timeline and now the writers have explained how it works...
WARNING: THIS ARTICLE CONTAINS MAJOR AVENGERS SPOILERS
Avengers: Endgame is here and it's iconic. However, a few fans are perplexed by the timeline and how time travel works in the Marvel film.
As soon as Avengers: Infinity War came out, people began theorising as to how the remaining Avengers would save all of the people who died in Thanos' snap. Would they be able to simply undo his actions using science? Would they work out a way to resurrect the dead? Would they travel back in time to undo his actions? It turns out that time travel comes into play in a very big way but fans aren't sure how it works. Now the writers have explained Marvel time travel in detail.
What is the science behind the Avengers: Endgame time travel?
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Speaking to the New York Times, Stephen McFeely revealed that producer Kevin Feige originally suggested they incorporate time travel into the film. He stated: "Kevin at one point said, I would like to use the Time Stone, or use time as an element. It let us spend a few weeks seeing what’s the kookiest thing we could do with time and not break the movie." However, the writers were all reluctant to go down the time travel route at first.
Christopher Markus then explained: "We all sat there going, really? We’re going to do time travel? It was only when we were looking at who we had available, character-wise; we hadn’t used Ant-Man yet. And there really is, in people’s theory of the Quantum Realm, a time thing in the MCU, right now, available to us, with a character we haven’t used yet. We have a loophole that’s not cheating."
In the Quantum Realm, space and time are essentially irrelevant so, if you can master it, you can travel through time. It's all thanks to Ant-Man explaining this to the Avengers in Endgame that Iron-Man is then able to create a literal time machine which allows the Avengers to navigate through time and save the entire universe.
Why do changes to the past not alter the present in Endgame?
In the NYT profile, McFeely goes into detail about why the Avengers actions in the past don't really change the present at all: "It was by necessity. If you have six MacGuffins and every time you go back it changes something, you’ve got Biff’s casino, exponentially. So we just couldn’t do that. We had physicists come in - more than one - who said, basically, “Back to the Future” is [wrong]." Okay. This makes sense.
Markus then added that their version of time travel works exactly how Hulk explains it in the film: "If you go to the past, then the present becomes your past and the past becomes your future. So there’s absolutely no reason [what's happened in the past and present] would change." Every time travel film before Endgame made up their own rules for time travel, so you can't compare them.
This is why the Avengers can't just go into the past and stop Thanos from ever getting the Infinity Stones. It would not undo what's already happened. Instead they have to collect all the Infinity Stones to use themselves to bring back the dead (Hulk restores them). It also explains why 2023 Nebula doesn't die when she kills 2014 Nebula.
Why do the Infinity Stones have to be returned then?
The Ancient One (Tilda Swinton) explains this. "The Infinity Stones create what you experience as the flow of time. Remove one stone and that flow splits. Now, this may benefit your reality, but my new one, not so much. In this new branch reality, without our chief weapon against the forces of darkness, our world would be over-run and millions would suffer. Tell me, Doctor, can your science prevent all that?"
In other words, removing stones from the past creates new realities which need the stones to protect them. Hulk works out how to prevent this though: “We can erase it. Once we’re done with the stones, we can return each one to its own timeline the moment it was taken so, chronologically, in that reality, it never left.”
Captain America does just that at the end of Endgame and then grows old with the love of his life Peggy.