Avengers Endgame time-travel is one of the most unique takes on the time-traveling genre. The last time I was this fascinated by a time-travel event was back in 2004 while playing Prince of Persia Warrior Within. However, in the Avengers Endgame, the concept of multiple timelines comes alive, like the one featured in Spiderman: Into the Multiverse.
Avengers Endgame Time-Travel Explained
Avengers Endgame deals with the Quantum Realm as a possible way of executing perfect time-travel. In the movie, the Avengers decide to retrieve the infinity stones for themselves by going back in time and collecting them one by one. The heroes plan on returning the stones because infinity stones keep the timeline from fracturing into alternate ones.
For this purpose, the Avengers use a device which shrinks them down to quantum level (size of less than 0.1 nm) and sends them across different time periods, functioning like a ‘GPS map.’
The major point that scriptwriters make is that each time-traveler has its own timeline. Meaning, any difference in your past will not change your present but your future. If you make a change in the past then it will create a different timeline separate from that point and without adding any changes to your own.
Thus, if the Avengers took Infinity stones from their original place forever, then they would create an alternate timeline in which anything could happen. It won’t affect the time-traveling Avengers or their reality but people could suffer in alternate ones.
The concept of returning the Infinity Stones is a very clever one because it buffers concepts like the Grandfather Paradox and the Butterfly Affect. Theoretically, every different move that Avengers make in the past should have created a new timeline. However, the Inifity Stones act as a ‘quick-fix’ to those effects by creating an imaginary boundary around time.
The Avengers keep this in mind, and that’s why they keep their identities secret when traveling back in time.
How To Time-Travel?
If you’re watching a person time-travel in the same way as the Avengers do, then both of you will experience the passage of time differently. From your perspective, the person time-traveling would only be gone for a few seconds while for them the time could be as long as they’d like.
That’s because they’re navigating through time without making any extra time. Think of it this way, if you’re watching a 5-hour long video, then at any single time the video can’t be more than 5 hours long.
That doesn’t mean that they’d stay young or immortal. People doing time-travel will age normally because their cell biology is the same. It’s just that if you’re watching them, then their 70 years or 7 seconds spent in the past would look the same to you–just like it happens in case of Captain America.