During Endgame, the Avengers find a method of time travel, and use it to

recover the Infinity Stones so they can undo Thanos' snap.

During the movie, their ability to time travel this way is strictly limited by

their limited supply of Pym particles and inability to acquire more, due to Dr. Pym's death by snap.

However, by the end of the movie

the snap has been undone, returning Dr. Pym and presumably providing an additional supply of Pym particles (how else would Steve Rogers have been able to return the Infinity Stones to the timeline points they were retrieved from?).

With that limitation removed, what, if anything, prevents the Avengers from solving any and all problems that may come up in post-Endgame movies with time travel?

To clarify, the presence of


at the end of the movie indicates that at the very least individuals (heroes, their loved ones, etc.) can be saved from things that definitely killed them in the past.

  • 2
    Time travel is flaky, some would even say "wibbly, wobbly". So it's not a safe or sure-fire technique to use. In Endgame they used it as a literal last resort option. Most problems can be solved using much more conventional methods, such as "bash them on the head with fists" or "diplomacy".
    – Möoz
    Commented May 9, 2019 at 23:12
  • We also don't know how 'sticky' that * spoiler * appearance is. After the Final Snap or Steve's return of the stones, it may have sent * spoiler * back.
    – Möoz
    Commented May 9, 2019 at 23:15
  • 1
    They really shouldn't have brought back Gamora, it poked a hole in everything time travel related. Commented Aug 27, 2019 at 11:07

3 Answers 3


Hank Pym.

In Ant Man (2015), Hank stated:

Hank Pym: I spent thirty years protecting that technology from a Stark, I sure as hell don't intend to give it to another! This isn't cute technology like the Iron Man suit! This could change the techs of reality! Besides, they must already have their hands busy throwing cities out of the sky...

Time travel requires a Quantum tunnel, Tony's GPS device plus Pym Particles. If Hank won't give them up, then there's no time travel. He wasn't around in Endgame to object to their use, but he's a bit of a curmudgeon and unlikely to change his opinion on something he's protected so vehemently for all those years.

Also remember that changing the past doesn't affect your present, which means that unless you were trying to collect lost items again, the time travel plan won't help all that much.

  • 1
    And why didn't the Avengers use their time travel machine during Endgame to get more Pym Particles to give them infinite tries? Hank Pym. =)
    – Kai
    Commented May 9, 2019 at 20:39
  • 1
    @Kai Technically they did recover more during the course of the movie. Commented May 9, 2019 at 20:42
  • 1
    The movie still glosses over the fact that you could go back in time 10 minutes and steal a gallon of gasoline from yourself AND the pym particles you're about to use to go back in time and bring them to the present... now you have two gallons of gasoline and the same number of pym particles. Repeat ad-infinitum and you've got unlimited resources of any kind.
    – Jherico
    Commented May 9, 2019 at 22:35
  • 3
    Also, they briefly demonstrated the technology to make old people young again and just ignored the incredible potential benefits because it wasn't the kind of time travel they were looking for at the time. Reed Richards is Useless
    – Jherico
    Commented May 9, 2019 at 22:46
  • @Jherico You never know, that might be how they de-age the original Captain America in a phase or two if they need him real bad...
    – Dave
    Commented May 9, 2019 at 22:55

Time travel, as presented in Endgame, doesn’t solve all problems.

Merely travelling back in time does not, as demonstrated in the movie, change the present. So, unless there’s something you want to borrow from the past to help the future, and you’re prepared to create a new alternate reality while doing so, it’s not a helpful idea.

It only solved one problem in Endgame because they travelled back in time to borrow the Infinity Stones (at great risk to themselves and the alternate timelines that created), then had Hulk snap his fingers (which was fairly risky for Hulk himself) — and while doing so, they risked past Thanos reclaiming the past Stones and doing something even worse, and may have created new problems in new alternate realities (like Loki portalling off with the Tesseract).

In short, it's an incredibly risky thing to do. Worth it to save the lives of half of the living beings in the entire universe? Just about. Worth it for anything else? Almost certainly not.

But who knows? Maybe every future MCU movie will have a time travel section!

  • 1
    Yes, time travel doesn't change the present (or at least it doesn't at points in the timeline where Infinity Stones exist). But you can still retrieve objects and people from the past (e.g. Gamora) and have them cheerfully continue living despite having died at a previous point in the timeline. Commented May 9, 2019 at 20:36
  • 1
    @ObliviousSage you can! But you’d have to convince them to come. And would it really help anything? They have to die sometime. Commented May 9, 2019 at 20:38
  • I would think the convincing would be pretty easy if the subject is aware that individuals can be saved from death via time travel in this manner. Unless the death you're trying to save them from is via suicide. Commented May 9, 2019 at 20:45
  • 2
    @NKCampbell That would create an alternate timeline where Tony had vanished and the universe ended up destroyed because he wasn't there. That's something the Avengers are desperately trying to avoid...
    – Dave
    Commented May 9, 2019 at 22:03
  • 1
    well sure - but they are already sort of spawning and abandoning alternate timelines anyway ;)
    – NKCampbell
    Commented May 9, 2019 at 22:46

When you time travel in the MCU, you create another reality. It’s existance does not directly change your own timeline. You can go get things from it though and bring them to your universe. They can’t bring people back that way, because it would rob their native universe of them, and they also couldn’t save that universe from Thanos. Say they saved iron man, that would mean Thanos destroyed that universe.


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