The Hulk accidentally created an immortality machine while testing time-travel in Avengers: Endgame. The arc Marvel Studios had been building for its cinematic universe for over a decade reached its highest point with Avengers: Infinity War and Avengers: Endgame, bringing together all its superheroes to fight Thanos and his armies. Infinity War saw the Mad Titan collecting all the Infinity Stones and mounting them on the gauntlet, thus fulfilling his plan of wiping out half of life in the universe.
Avengers: Endgame followed the surviving heroes as they tried to undo the snap and bring back those who vanished, while also teaming up to defeat Thanos once and for all. The solution to get to the stones before Thanos and prevent the decimation was to travel back in time to collect the stones. The possibility of time-travel through the Quantum Realm was brought up by Ant-Man, and the method was perfected by Bruce Banner (now merged with the Hulk) and Tony Stark, who initially refused but joined the cause after thinking back to the death of Peter Parker.
Before Stark agreed to help, Hulk, Ant-Man, Captain America, and Black Widow began working on a time machine, and like any other “experiment”, it had to be tested – and it was during those tests that it was revealed the Hulk had accidentally created an immortality machine as well as a time-travel one.
Hulk Created An Immortality Machine By Accident
The tests consisted on sending Scott Lang aka Ant-Man to the past and back, but he wasn’t exactly the same when he returned. The Hulk sent him back a week, let him walk around for an hour and then brought him back in 10 seconds (as Scott said, “perfectly not confusing”). When he came back, Scott was an understandably confused teenager. In an attempt to reverse the “damage”, Scott was sent back again and returned as his much older self, with the next attempt bringing back Scott as a baby. He was eventually brought back as his present self, and the machine was perfected with the combined efforts of Stark and Hulk.
However, and even though the Hulk’s first machine did work in terms of time-travel, its major flaw accidentally made it an immortality machine. Teen Scott could have moved on with his life and go back and forth in time again to become young once more. This accidental invention was pointed out by a Reddit user, who added that, if they wanted to, the Avengers could use it for selfish purposes, such as the Hulk to heal his arm (which was severely damaged after wielding the nano-tech gauntlet) or even Captain America to become young again and continue being hero (though that one is unlikely).
An “advantage” of this machine is that the subject is able to keep its memories, even if it goes way back in time (baby Scott absolutely remembered his whole life), which would come in handy for those who want to become younger in order to keep on with their heroic deeds. It’s unlikely this machine will be used in future MCU films, mostly because it ended up becoming the strictly time-travel machine the Avengers used and it was destroyed during Thanos’ attack on the Avengers HQ, but it’s a fun detail and a very good example of a happy mistake.
Next: Marvel’s Original Plans For Thanos Would Have Improved His Character Journey