- Warning: There are major spoilers ahead for ” Avengers: Endgame.”
- In “Avengers: Endgame,” our heroes head backwards in time to retrieve the Infinity Stones from various points in the past (because Thanos destroys them at the beginning of the movie) to reverse the “snap” from “Avengers: Infinity War.”
- But during the process of that time travel, Loki absconds with the space stone, and when Captain America goes back to put each stone in its rightful place in the time stream, he elects to stay behind and grow old with Peggy Carter.
- These events have sparked debates among fans and the movie’s directors and the screenwriters. By staying behind to marry Peggy, the directors said that Steve Rogers causes an alternate timeline to branch-off from the Marvel Cinematic Universe.
- The screenwriters have said that Steve and Peggy’s life occurs within the existing MCU timeline.
- INSIDER chatted with one of the science advisers for “Avengers: Endgame” to get his take on all this time travel. He thinks that Cap grows old in the MCU, not an alternate one.
Marvel fans breathed an audible sigh of satisfaction at the end of “Avengers: Endgame” when Steve Rogers and Peggy Carter got the happily ever after that they’d been denied since the end of World War II. But Captain America’s decision to “try some of that life that Tony was telling me to get” after he put all the Infinity Stones back in the right time and place has some viewers wondering whether or not the decision created an alternate timeline.
Directors Anthony and Joe Russo said, “If Cap were to go back into the past and live there, he would create a branched reality… he lived his married life in a different universe from the main one.”
But, the directors said Cap had to jump back into the main universe at the end of the movie to pass the shield back to Sam.
One the other hand, the screenwriters Christopher Markus and Stephen McFeely, argue that “Steve going back and just being there would not create a new timeline.”
So what really happened?
Sean Carroll, one of the science advisers on the movie and a theoretical physicist from the California Institute of Technology, told INSIDER that he sides with the screenwriters on this one.
Carroll thinks that Cap married Peggy in the existing Marvel Cinematic Universe, not an alternate one
“I think in this case, I see no reason to doubt that [Cap’s] in the same timeline,” Carroll said. “If I remember correctly, when Cap visits elderly Peggy in ‘Captain America: The Winter Soldier,’ she doesn’t say who she gets married to.”
In the scene Carroll’s referring to, we see photos of Peggy and her children, but there doesn’t seem to be a father visible.
“She could’ve married Cap,” Carroll said. “That’s completely plausible to me.”
What’s more, the science advisor said, “When Cap went back to the 1970s [to retrieve the tesseract and Pym particles with Tony Stark], there’s a picture of Steve Rogers on her desk. If she married someone else, that would be weird.”
But for Carroll, the biggest tell is how Steve appears on the bench at the end of “Avengers: Endgame.”
“Cap snuck in. He didn’t materialise in the time machine, but knew when they’d be there and so just showed up at the bench at the right time,” Carroll said.
Where do alternate timelines come from?
The movie takes a lot of liberties when it comes to time travel. Both “Avengers: Endgame” (and subsequent Marvel movies like “Spider-Man: Far From Home”) bring up the concept of parallel universes, and how that concept is tied to Ant-Man’s quantum realm.
Quantum mechanics says there are lots of possible futures and lots of possible pasts that exist at the same time, each with differing probabilities of happening, according to John Baez, a mathematical physicist at the University of California, Riverside.
Each of those futures and pasts exist as an alternate universe and reality at the same time, and in the same place, which physicists refer to as the Many Worlds Theory.
According to this theory, any changes in the past create entirely new universes (the so-called branching off of multiple timelines that the Ancient One warns Bruce about before giving him the Time Stone). That’s why it was so important that the Avengers put the Infinity Stones back in precisely the right time and place in the past after they were done using them.
But what about Loki?
The one other loose end that has fans reeling is Loki’s escape with the tesseract in 2012, when Hulk knocks the Space Stone from Tony’s grasp, allowing the god of mischief to teleport away.
In an interview, the Russo brothers told Business Insider that the Loki of that period actually created his own timeline.
“It gets very complicated, but it would be impossible for [Cap] to rectify the timeline unless he found Loki,” Joe Russo said. “The minute that Loki does something as dramatic as take the Space Stone, he creates a branched reality.”
Carroll said he wasn’t sure either way. “I’m confused about that one myself,” he told us.
The possibility of Loki living in an alternate reality has implications for the “Loki” TV series in the works for Disney’s upcoming streaming platform, Disney Plus.
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