WARNING: This article contains spoilers for Stranger Things season 4 volume 1.
Stranger Things season 4 volume 1 finally reveals the origin of the Upside Down. The Upside Down lies at the heart of Stranger Things, the origin of the countless threats that have plagued Hawkins. The residents of Hawkins are increasingly coming to believe their town is cursed, and the Upside Down is that curse.
The Upside Down is an alternate dimension that's eerily similar to Earth, a harsh and inhospitable environment that is ruled by the Mind Flayer. All the other creatures of the Upside Down are bound together in the Mind Flayer's hive mind, meaning that an encounter with any one creature risks drawing the attention of the Mind Flayer itself. Every season of Stranger Things has introduced new monsters, typically variants of the Demogorgon.
Stranger Things season 4 finally explains the origin of the Upside Down, and even hints how it came to resemble Hawkins. It does so through a series of retcons that rewrite Eleven's own backstory, revealing she opened the first Gate to the Upside Down after a pitched telekinetic battle against Number One in 1979 - a memory she had repressed. This was the true inciting incident of Stranger Things, explaining the events surrounding Eleven's escape from Hawkins Lab.
The Upside Down Origin Explained
The last few years have seen Stranger Things expand into a transmedia franchise, with a range of tie-in comics and novels. The latest miniseries, Stranger Things: Kamchatka, serves as direct setup for season 4 - and it introduces readers to Stranger Things' version of the multiverse, in an unlikely manner. It reveals Dr. Brenner wasn't the only scientist attempting to unlock powers like telepathy and telekinesis, with a Soviet scientist named Dr. Boris Orlov working on the same principles in the U.S.S.R. Orlov was one step ahead of Brenner, theorizing that telekinesis could be used to open gateways to "infinite worlds."
This perfectly sets up Stranger Things season 4's flashbacks, which reveal the telekinetic duel between Eleven and One escalated until she blasted open a sort of "window" into the Upside Down. This projected Number One through an infinite multiverse, until by sheer chance he emerged in the realm that would come to be known as the Upside Down. The opening of the window appears to have brought these two dimensions closely together, meaning the boundaries between them are disturbingly thin around Hawkins.
Why The Upside Down Is Stuck In 1983
Stranger Things season 4 revealed the Upside Down is stuck in 1983. Although the Upside Down has always seemed to be an imperfect duplicate of Hawkins, Nancy realized it is stuck in 1983 - specifically, on the very same day Eleven opened that first Gate. The clear implication is that the opening of the Gate bound this flawed copy of Hawkins on to a preexisting universe, creating the Upside Down as viewers have known it. The Mind Flayer, the Demogorgons and the other creatures of that realm are presumably the original inhabitants of this dimension, no doubt shaken when their reality was blended with Hawkins.
Why The Upside Down Has Earthquakes
Nancy, Steve, Eddie, and Robin find themselves briefly stranded in the Upside Down in Stranger Things season 4. It appears to have changed a little since season 1, when Will was stranded in it; it's a little easier for humans to survive there, because the air is no longer quite so difficult to breathe. Even more curiously, though, the Upside Down is experiencing frequent earthquakes. These are not being duplicated in the real world, suggesting something unique is happening there.
The most likely explanation for all this is that the Upside Down is now unstable. It's quite possible that the opening of the Gate "moved" the dimensions closer together, and that this process is continuing even now - with the Upside Down moving ever closer to Hawkins. This may no longer be an accident; Stranger Things season 4 revealed One survived in the Upside Down, becoming Vecna, a powerful villain the Hawkins kids deduce is the Mind Flayer's "five-star general." He is now using his telepathic and telekinetic powers to break through the dimensions, preying on individuals who have a strong sense of guilt or shame, ultimately killing them. While Vecna no doubt takes tremendous pleasure in the pain and suffering he is causing, he appears to have a set goal in mind; every one of those deaths opens another Gate. If one Gate brought the two dimensions closely together, then the opening of multiple Gates could be creating an irreversible connection. Through Vecna, the Upside Down may well be invading Hawkins.
How Old Is The Upside Down?
Stranger Things season 4 has been billed as "the beginning of the end." It's quite appropriate, therefore, that volume 1 has begun to finally answer some of the show's greatest mysteries. The pseudoscience surrounding the Upside Down and its monsters is finally beginning to make sense; they are creatures who inhabit another world, a pocket dimension separate from the Earth. This may well have existed since the dawn of time, with the Mind Flayer and the various monsters that comprise its hive mind thriving in a sort of "bubble universe." A copy of Hawkins was integrated onto the Upside Down when Eleven opened the Gate, perhaps already indicating the dimensional instability, and things are only going to get worse.
The intriguing question is whether or not the Mind Flayer is still in control of the Upside Down's hive mind. The Hawkins kids compared Vecna to the Mind Flayer's five-star general, but it's entirely possible he has now taken over; the Mind Flayer itself was nowhere to be seen in Stranger Things season 4, while Vecna clearly drew on the power of the hive mind to open his Gates. If Vecna has indeed taken control of the Upside Down, then it has become more dangerous than ever; before it was directed by animal instincts, but now it is under the control of a malevolent being who longs to wipe out the entire human race. If the dimensions do collide in Stranger Things season 4 volume 2, then there really will be war on a scale even the residents of Hawkins have never imagined.