With Earth's mightiest heroes looking for a way to undo Thanos' universe-halving snap in Avengers: Endgame, the mysterious Quantum Realm, first introduced to the MCU in Ant-Man, and its time vortexes might be their best bet. Here's what we know about this subatomic world "where all concepts of time and space become irrelevant" and how it might be the key to undoing the Mad Titan's Great Dusting.
In the Comics
In the comics, the Quantum Realm is called the Microverse. Disney can't use that term because Paramount owns the rights to it, along with the Micronauts. In the Microverse, the Micronauts live in the Homeworld region, which...you know what? This won't help matter for Avengers: Endgame. The Microverse of the comics is too insane. What's most important for MCU fans to understand is that Microverses are wholly independent parallel dimensions that exist in a different plane than ours. From the Microverse wikia page:
"A Microverse is a dimension that can be reached from the Earth dimension by shrinking with Pym Particles and thus compressing the person's matter to a certain point, thereby forcing it through an artificially created nexus into the other universe. The Microverses were once erroneously believed to exist within atoms. They are all described as parallel dimensions, rather than universes within universes."
When you go to the Microverse you aren't just shrinking within our dimension, like a Russian doll of universes; you travel to a different one altogether.
Hank Pym, who earlier in life had tried to harness the incredible power of quantum energy, spent years studying the Quantum Realm after his wife Janet van Dyne went subatomic to stop a nuclear warhead. Despite his attempts to find her, Hank was unable to gain any hard science to understand the Quantum Realm and didn't even know if it was possible for someone to survive there. He warned Scott against messing around with his regulator for this reason.
But Scott did go subatomic to save his daughter Cassie, and as he shrunk he passed through smaller and smaller worlds, each beautiful and haunting in its own way. One featured a mirror world, similar to a dimension we saw in Doctor Strange. By the end Scott ended up in an empty, dark void with only specks of light. If not for Cassie's cries and his enlarging disc he never would have come back, though Scott didn't initially remember anything from his trip.
Doctor Strange, the Ancient One, and the Multiverse
The Quantum Realm is just one of the other dimensions beyond the Earthly Plane the Avengers exist in. In Doctor Strange, the Ancient One told Steven Strange about how vast and varied the universe really is beyond the world humans experience:
"You think that this material universe is all there is? What is real? What mysteries lie beyond the reach of your senses? At the root of existence, mind and matter meet. Thoughts shape reality. This universe is only one of an infinite number. Worlds without end. Some benevolent and life-giving, others filled with malice and hunger. Dark places, where powers older than time lie. Ravenous, and waiting."
While it's easy to think of the Quantum Realm as existing in our own dimension in tiny form, it's one of the many parallel worlds to our own, just like the Astral, Dark, and Mirror Dimensions explored in Doctor Strange. Is it possible Scott Lang traveled through some of these himself as he shrunk, especially the Mirror Dimension? It's not clear, but what is important is understanding the Multiverse, and therefore the Quantum Realm, is as much magical as it is scientific. Masters of the Mystic Arts can move between dimensions with their sling rings, while Hank's Pym Particles are the only way anyone else has. However, it's also possible that the dimension we saw young Gamora in after Thanos snapped his fingers is itself a unique parallel dimension, a type of Soul Dimension. And if the Soul Stone doesn't kill you and instead just sends you (or your energy) to a different dimension, it might be possible to return from it.
Ghost, Quantum Energy, and Connections Between Dimensions
After Scott survived his trip to the Quantum Realm, Hank Pym and Hope van Dyne built a portal to try and reach it. They briefly opened their Quantum Tunnel, which can be used to send someone to a specific coordinate within the QR (as opposed to Scott, who shrank down to a random spot). During that very brief moment they opened the tunnel in their lab, Scott had what he thought was a weird, vivid dream at his home. It turned out to be a message from Janet van Dyne. Scott's brief journey to the sub-atomic world made him become "quantumly entangled" with Janet, their two minds sharing a direct connection. She had survived there for 30 years, and their quantum entanglement (a sort of telepathy across dimensions) was Janet's way of planting a type of magical antenna in Scott's brain. She used this to "speak" through Scott.
Hank and Hope were able to get Janet's message from Scott for exactly when and where they could find her in the Quantum Realm. However, Ava Starr (a.k.a. Ghost) tried to stop them. As a child Ava was hit with a tremendous amount of quantum energy when her father's own Quantum Tunnel exploded. (In an explosion that looked a lot like Ego the Living Planet's flowers growing in Guardians of the Galaxy, Vol. 2). That made Ava quantumly unstable."They call it 'molecular disequilibrium,'" Ava said, "A rather dull name, I think. Doesn't quite do justice to what it means. Every cell in my body is torn apart and stitched back together, over and over every day." Ava's bleeping in and out of the Earthly plane is also known as Quantum Phasing, "when an an object moves through different states of matter." This chaotic state means Ava exists in "multiple parallel realities.
"Her condition makes her something less than tangible, which is how she is able to move through objects. With great focus she can grab onto things briefly, at least long enough to punch and kick people (with incredible force thanks to the quantum energy in her body). Her S.H.I.E.L.D. suit also helps stabilize her powers so she can harness them and go from tangible to intangible when she needs to walk through walls or go invisible. Ultimately Ghost's quantum displacement means she exists in both our dimension and the Quantum Realm, and therefore doesn't fully exist in either. To ease the tremendous pain her phasing causes at all times, Bill Foster built her a quantum chamber that releases quantum energy waves that also stabilize her. However, that's only a temporary reprieve, and since Ava can only harnesses quantum energy involuntarily, a lack of it is killing her.
Foster's plan was to fix Ava by stealing all of the quantum energy (via the tunnel) that Janet had been storing in the Quantum Realm. Foster and Ghost would be able to locate Janet thanks to Scott's link with her. Hank was certain that taking Janet's quantum energy would kill her though, and he was right. After much hullabaloo and car chases, Hank was able to go into the Quantum Realm via the tunnel to retrieve Janet exactly where she said she'd be, which was a place past where even Scott had gone.
Hank went to the same black void Scott ended up in, but then Hank shrunk even smaller (through yet another mirror world) into a land of incredible color and life. It looked like a totally different dimension unto itself, as though Hank had traveled through a portal, like the kind of nexus from the comics. We know what that place is called because Janet described it earlier when she spoke through Scott. "In the wasteland beyond the Quantum void, it's very dangerous on the human mind." That gorgeous world, where Hank also started phasing like Ghost until Janet touched him and stabilized him, didn't look like a wasteland. From a deleted scene we know this place has intelligent life, "worlds upon worlds, entire civilizations," including Easter eggs of Microverse cities.
When Janet finally returned to our Earthly plane, she had 30 years worth of insight into the Quantum Realm. First, Janet was able to feel Ava's pain without touching her. Just like with Scott, Janet can connect with others via a quantum connection. She managed to transfer some of her own quantum energy with her hands, like a wizard, to Ava to help stabilize her. It instantly stopped Ava's phasing and saved her life, which only had days left, though it wasn't a permanent fix.
That's why Scott took a trip to the Quantum Realm himself to directly harness "quantum healing particles" (indicating there are different, distinct forms of quantum energy) with a specialized canister, which would then be used to save their "new friend" Ghost. Unfortunately, that trip was not a snap, and when Hank, Janet, and Hope turned to dust, Scott was stuck there. We know he will come out in Avengers: Endgame, however long that might be after Infinity War.
The Rules of Existence and Time Vortexes
Time and space are so different in the Quantum Realm we can't fully comprehend how they work there, to the point they might be totally meaningless to us. We do know Janet van Dyne aged while she was there though. Some rules of our Earthly plane, especially regarding our bodies, still apply to us while we are there. We seem to have a reality unto ourselves, so even though living there allowed her to evolve to the point she can pass quantum energy from her body to others just using her hands, she is still human.
And yet, despite everything Janet taught us about this strange dimension, the most important lesson was one she didn't tell us much about. As Scott was getting ready to dive into the Quantum Realm via the tunnel, Janet said, "Don't get sucked into a time vortex; we won't be able to save you."
That way-too-casual warning indicates that within the Quantum Realm there are cosmic whirlpools of time that will suck you in. It sounds like someone can be lost in time (at least time as it works in our plane of existence) and that's why they wouldn't be able to save Scott from a vortex. He wouldn't just be lost in an infinite void of another dimension like Janet; no one would even know "when" he was lost. If he went into a vortex in 2018, he might emerge on the other side of it in 1998 or 2028 or 2018 B.C. Maybe!
But what if someone could harness a time vortex as their own inter-dimensional time machine? For example, if Scott were to come out of the Quantum Realm to find half of the universe gone, could he travel back into the Quantum Realm, enter a time vortex, and emerge in the past early enough to warn the Avengers about Thanos? Granted, linear time like we experience doesn't apply there, but that doesn't mean portals from the Quantum Realm can't be used to manipulate our own.
Could Scott Lang create a new timeline? An alternate reality that exists in its own parallel dimension? Would fooling around with powers we can never truly understand create its own problems and future enemies?Probably, but it's a risk the Avengers will likely be willing to take to undo the Mad Titan's Great Dusting.