Marvel Cinematic Universe began exploring its cosmic side. Ant-Man did its part by introducing the Quantum Realm, a dimension in the multiverse that can only be accessed through very specific (and complex) methods.
Directed by Peyton Reed, Ant-Man follows master thief Scott Lang (Paul Rudd), who takes part in the experiments of Hank Pym (Michael Douglas) involving a super-suit that gives the wearer the ability to shrink in scale but increase in strength. Pym revealed that his wife, Ant-Man & The Wasp, and while she displayed some interesting abilities gained during her time in the Quantum Realm, it wasn’t explained how she survived there for so long.
The Avengers: Endgame. Janet spent decades in the Quantum Realm, and aside from some superpowers (such as quantum particle manipulation, healing, and entanglement), she was unharmed when she came back, which has made fans question how she managed to survive there, and they believe the answer could be in the comics.
In the source material, the Quantum Realm is known as the Microverse, and it’s formed by many different dimensions. The Microverse is the home of the Micronauts, a superhero team, and Wasp was also trapped there during Secret Invasion. Quantum Realm.
Of course, Marvel left this intentionally unanswered as there’s a lot to explore and learn about the Quantum Realm within the MCU, and it will surely be an important topic to address in Ant-Man 3, but given that Janet showed no signs of damage upon her return, it could be safe to assume (for now, at least) that she received helped while in the Quantum Realm, though exactly from who will remain a mystery.
