Warning: Spoilers for Stranger Things season 4, volume 1!

In Stranger Things season 4's "Chapter Seven: The Massacre at Hawkins Lab," it was confirmed that the Upside Down was stuck in 1983, and there are several reasons why. The Upside Down has been an integral setting in Stranger Things, serving as a mysterious alternate dimension parallel to the real world. When doors, or "gates," have opened between the two dimensions, threats from the Upside Down leak into Hawkins, Indiana. At times, humans have been able to investigate the Upside Down, including houses and infrastructure that mirror Hawkins, albeit in a darker environment covered in spores, roots, and swirling ash-like dust.

Will Byers was the first person to spend ample time in the Upside Down and make it back to the real world. Though he was later confirmed to be the new host of the Mind Flayer, it confirmed that humans could travel throughout the alternate dimension. In Stranger Things season 4, episode 7, "Chapter Seven: The Massacre at Hawkins Lab," Nancy, Robin, and Eddie followed Steve through the "water gate," leading to the Upside Down. With the threat of Demobats, Nancy suggested going to the Upside Down version of her house to retrieve her guns. While there, she discovered that the guns hidden in her room weren't there. This was because her guns hadn't existed yet, realizing through the diary in her room that the Upside Down was stuck in November 6, 1983.

Related: Stranger Things Season 4's Episode Lengths Are Ridiculous

The date of November 6, 1983, is significant in Stranger Things' Upside Down timeline for several reasons. First, it was the date that Dr. Martin Brenner requested that Eleven make contact with a "monster" with her telekinetic powers. Out of fear, she accidentally opened a portal between her world and the Upside Down, allowing the Demogorgon to travel through. As Eleven escaped Hawkins Lab, Will Byers was also taken by the Demogorgon into the Upside Down that same day. With Eleven opening a gate and the Demogorgon's actions in Hawkins, this was likely the first time that elements from both dimensions mixed. The events of the dimensions bleeding together likely locked the Upside Down in November 6, 1983, in some kind of endless time loop. Granted, it's important to examine why the Upside Down didn't get stuck in September 8, 1979, when Henry Creel/Number One was banished to the dimension.

Why The Upside Down Isn't Stuck In 1979

Stranger Things Season 4 Number One Fate

When Eleven tapped into her memories to rediscover the whole truth centering around the massacre of Hawkin's Lab, Vecna's true identity was revealed. Henry Creel was "001," but his powers were suppressed out of fear that he couldn't be controlled. Henry wanted Eleven to join him on his mission to take over the world, and when she declined, the pair faced off in the Rainbow Room. Eleven overpowered him, and Henry's body turned to dust before disappearing through a red crack in the wall. The crack Henry's dusted body went through was different than the gate Eleven opened in Stranger Things season 1. Whereas that one was more like a door-like portal humans and monsters could travel through, the entry in 1979 was more like a window.

As Henry's reformed body flew through the air, exposure and lightning transformed him into Vecna. Interestingly, the surrounding environment looked nothing like Hawkins. The dimension shown had two mirrored layers covered in mountains and what looked like lava flows. This suggests that the Upside Down in Stranger Things wasn't formed yet in 1979. That means the replication of Hawkins either occurred the day Eleven opened the gate in 1983, or Vecna used his powers to replicate Hawkins but stopped that day as his sights turned to Eleven.

More: Was Stranger Things Season 4 Worth The Wait?

Stranger Things season 4, volume 2 releases July 1, 2022, on Netflix.

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