Following Avengers: Infinity War, Ant-Man and the Wasp was a lighthearted affair that ended in a tragic but important setup for how the Avengers would save the universe from Thanos (Josh Brolin) and reverse his snap, which caused The Blip. The film's biggest hint was Hank Pym (Michael Douglas) venturing into the Quantum Realm and finding his wife, Janet Van Dyne (Michelle Pfeiffer). This introduced the original Avenger to the Marvel Cinematic Universe and showed how time operated differently in the Quantum Realm. This, in turn, eventually led to the Avengers using the Realm to travel through time in Avengers: Endgame.
In the 2015 film, Ant-Man, it was revealed that during a mission, Janet was forced to shrink between the molecules to stop a ballistic missile. While her action saved lives, it also caused her to be lost for decades. Hank went years believing she was dead while silently hoping that there was a chance to bring her back. Thanks to Scott Lang's (Paul Rudd) accidental adventure into the Quantum Realm, he sparked hope in Hank that Janet may still be alive. That hope would follow through in the sequel, where Hank Pym was able to find his long-lost wife. A deleted scene helped explain one of the many ways that Janet was able to survive for so many decades.
How Did Janet Van Dyne Live in the Quantum Realm?
When Janet was lost in the Quantum Realm, she was only left with her suit and genius intellect. By the time Hank was finally able to reconnect with her, she had become a survivor in the Realm. She carried a cloak, the mouthpiece from her Wasp mask, and a staff made from her wings. However, when Hank and Janet walked through the Quantum Realm in the scene "Worlds Upon Worlds," there was another device that helped her survive for several years.
In the scene, Janet explained to Hank how much more vast the Quantum Realm was than what they had previously thought. While they walked, they were cut off by a threatening and strange-looking creature. As Hank went on the defensive, Janet pulled out a device and spoke into it, saying, "Passing through, we stake no claim." The creature quickly responded by saying "Go in peace," and granted them safe passage, to Hank's surprise.
While there were many civilizations within the Quantum Realm, there was also a social structure. Janet requesting safe passage provides a glimpse into its society. It also showcased her innovation and resourcefulness while living in a foreign land. She was able to take the technology used in the helmet to speak to other creatures -- crucial communication that prolonged her survival.
Even though she gained abilities that cured Ghost (Hannah John-Kamen) of her endless pain due to her powers, it was Janet's mind that helped her last in the microscopic realm until her husband found her. The "Worlds Upon Worlds" deleted scene showed that there were many undiscovered aspects of the Quantum Realm that Ant-Man and the Wasp: Quantumania brought to life.