The Upside Down is a dimension existing in parallel to the dimension inhabited by humans. The Upside Down contains the same locations and infrastructure, but it is much darker, colder and foggier; it is overgrown with ropy, root-like tendrils and webs of biological matter, with spores floating in the air. The Monster is native to this dimension.
In 1983, a gate to the Upside Down was opened at Hawkins National Laboratory following experiments on a telekinetic child. This allowed the Monster to leave the dimension and take several Hawkins residents back into it, where most of them were killed. Their disappearances caused major disturbances in the lives of their friends and families, and Hawkins Lab went to great lengths to conceal the truth.
The history of the Upside Down prior to November 6th, 1983 remains a mystery. Exactly how long it had existed for, and how and why it came into existence, is unclear.
In one of Hawkins National Laboratory's experiments, a test subject labeled Eleven was immersed in a deep psychic state via sensory deprivation tank. She could observe people in different physical locations in this state, and Dr. Brenner sought to use this power to spy on enemy Russians.
While Eleven eavesdropped on a Russian spy, she accidentally encountered the Monster. At Dr. Brenner's request, Eleven made contact with the Monster by physically touching it while it fed off a large, yellow egg. In the moment contact was established, a gate between the two dimensions cracked open in the wall of the tank room, causing panic and confusion among the scientists.
The Monster was able to move through the dimensions via temporary portals it could create. It began harvesting the bodies of humans and animals, storing them in the Upside Down public library. Around the same time, Hawkins Lab began investigating the dimension and discovering exactly what it contained.
Although Will Byers was taken into the Upside Down by the Monster, he managed to evade capture for several days. During that time, he attempted to communicate with his mother after he realized he could manipulate electricity in his home dimension. On one occasion Will found a temporary portal in the wall, briefly talking to his mother directly through it before it resealed. The Monster eventually found him inside Castle Byers and took him to the library. Hopper and Joyce later entered the Upside Down via the Gate, eventually finding Will with an eel-like creature extending down his throat. After Will was resuscitated, the three returned to their home dimension.
At one point, Nancy Wheeler entered the Upside Down through a temporary portal in the base of a tree. She realized it was dangerous to stay in the dimension, quickly leaving before the Monster could find her.
Little is known about this mysterious dimension, and most of what is known is based on the speculation of Mike, Dustin, and Lucas. Eleven flipped the boys' Dungeons & Dragons game board to demonstrate that it is a reflection of their world, thereby naming it the Upside Down. Dustin compared it to the Vale of Shadows from the game: "a dimension that is a dark reflection, or echo, of our world. It is a place of decay and death, a plane out of phase, a place of monsters. It is right next to you and you do not even see it."
The boys asked their science teacher Mr. Clarke to explain inter-dimensional travel, and he dismissed it as an impossibility due to the massive amount of energy required. However, he explained that they could theoretically open a tear in space and time to allow passage, and such a tear would disrupt magnetic fields, which is a possible scientific explanation of the gate at Hawkins Lab. Dustin noted that the local magnetic field was acting abnormally, as compass needles pointed not towards true north, but towards the laboratory.
A lab scientist said the atmosphere was toxic to humans, hence why they wore hazmat suits to enter the dimension. However, it seems the atmosphere is only damaging after prolonged exposure, as Nancy entered for a brief moment and showed no signs of damage, whereas Will was exposed to the air for a week and became very sick.
In the Upside Down, Hawkins is covered in biological matter. It's entirely possible this biological growth extends beyond Hawkins and covers the rest of the United States, and potentially the whole Earth. The Monster and slug-like creatures exist in this dimension. The Monster appears to be the only specimen of its kind.
The slugs enter the bodies of weakened humans brought to the Upside Down and presumably feed off them. Will Byers was found with an eel-like creature extending down his throat and into his stomach; it is possible this creature was related to the slug or was indeed a more developed version of a slug.
The dimension also contains large, yellow eggs. It is unknown how these came to existence or what they contain, but the monster seems to feed off them, presumably killing any life form they could potentially spawn.
Connection to human-inhabited dimensionThe connection between the Upside Down and its opposite dimension was seemingly established when Eleven made contact with the Monster using her telepathic abilities, causing a gate to rip open in Hawkins National Laboratory. The Gate consisted of a wet and fleshy substance, seeming life-like as it emitted pulsing and growling noises. Similarly, the Monster created several smaller portals when moving between dimensions, but whereas these healed and closed up, the Gate in Hawkins Lab remained open and kept spreading into the other dimension.
People could faintly sense each other and communicate between dimensions, as evidenced by Joyce's feeling that Will was nearby and their following communication, Nancy and Jonathan calling out for and hearing each other, and Joyce and Jonathan speaking despite not seeing or hearing each other.
The movements of people and the Monster in the Upside Down affect the electronics in the opposite world. When someone in the Upside Down was close to lights in the corresponding location in the other dimension, the lights would either intensify or flicker. Will could manipulate the lights precisely in order to communicate with Joyce, despite the lights not being visible in the Upside Down. He also made the telephone ring and was slightly heard through noise and static, but it broke as the monster approached. It could be surmised that the presence of the Monster caused electronics to malfunction. On a larger scale, the Gate's opening caused power surges all over East Hawkins.
Behind the scenes
- Joyce's way of communicating with Will through the lights and hearing him in the walls of the house is an allusion to the 1982 horror film Poltergeist, in which young Carol Anne goes missing in another dimension and can be heard through the TV and walls. Also similar to Joyce, Carol Anne's mother ended up entering the other dimension to save her child.
- Ross and Matt Duffer, the creators of Stranger Things. gave this description of the unexplored mythology they are holding in reserve for the next season:
With the Upside Down, we have a 30-page document that is pretty intricate in terms of what it all means, and where this monster actually came from, and why aren’t there more monsters — we have all this stuff that we just didn’t have time for, or we didn’t feel like we needed to get into in season one, because of the main tension of Will. We have that whole other world that we haven’t fully explored in this season, and that was very purposeful.
- Matt said:
We wanted a simple drive and a somewhat simple mystery with bizarre pops of supernatural horror and then add a larger mythology behind this rift that we only know and refer to as the Upside Down because that’s what the boys decide to call it. They’re theorizing based on their knowledge from fantasy gaming and their science teacher, Mr. Clarke. That’s as much as we get to understand it.
- Ross said:
If there was going to be a season two, we would reveal more of that 30 page document, but we’d still want to keep it from the point of view of our original characters.
- Ross explained some of the consequences that might spin out of Will’s time in the Upside Down:
Will’s been there for an entire week, and it’s had some kind of effect on him, both emotionally and perhaps physically. The idea is he’s escaped this nightmare place, but has he really? That’s a place we wanted to go and potentially explore in season two. What effect does living in there for a week have on him? And what has been done to him? It’s not good, obviously.
Like the Monster, the Upside Down was designed by Aaron Sims Creative. In early development, there was consideration of time changes between the Upside Down and the regular world. Meaning, if it was daytime in Hawkins, it would've been nighttime in the other dimension and vice versa. In the end, they chose an all around dark, nightmarish design.
The Duffers noted that films like Alien, and the video game Silent Hill as inspiration for the Upside Down. Sims also took inspiration from Alien, but were more specifically influenced by the works of the Polish painter Zdzislaw Beksinski. Beksinski's works often reflected "...an otherworldly, hellish world, surrounded by a thin layer of something we can’t quite make out." Sims also didn't base their designs on any scientific theory of alternate dimensions, but around “the exploration of terrifying images and art.” Taking the idea of mold and the film that covers things that have decayed, they sought to create an image of a world that was basically "dead." The falling ash-like substance was designed with the intent to distinguish between the two worlds, but was hinted at having a possible direct connection with the Monster.
- ↑ "Exclusive ‘Stranger Things’ Art Reveals ‘Upside Down’ Secrets and Barb’s Alternate End"Screen Crush.August 22, 2016.