Stranger Things Season 5 Reveals the Upside Down Isn't What You Think It Is

Everything we've ever assumed about the Upside Down has been dead wrong. That's not a critic's hot take—it's a direct quote from Dustin in Stranger Things Season 5, and it completely upends the core mythology of the Netflix hit. The show's latest episodes reveal that the iconic, spore-filled realm isn't an alternate dimension at all.

Welcome to the Abyss

The series introduces a true alternate dimension, one that's been the home of Vecna (Jamie Campbell Bower) all along: 'the Abyss.' Drawing from Dungeons & Dragons lore, Mr. Clarke describes it as "a realm of pure chaos and evil." It's a yellow-tinged world of bleak mountains and floating rocks, and it's the original home of creatures like the Mind Flayer and the Demogorgons. Before this official name, fans knew this place as 'Dimension X' from released scripts.

The Upside Down: A Wormhole, Not a World

So, what is the Upside Down? Using Dr. Brenner's notes, Dustin figures it out: it’s a wormhole. It's not a place, but a pathway—a bridge connecting our dimension to the Abyss. This reveal has been hinted at all season, with references to the wormhole-like tesseracts in A Wrinkle in Time and Mr. Clarke’s lessons on Einstein-Rosen Bridges. Vecna and his minions have been using this bridge to travel to our world.

Eleven's Accidental Creation

The creation of this wormhole traces back to Eleven (Millie Bobby Brown). After she banished a young Henry Creel to the Abyss in 1979, Dr. Brenner's subsequent experiments pushed her to make psychic contact with beings in that dimension. According to the show, it was her contact with a Demogorgon in Season 1 that ripped open the first gate and created the Upside Down wormhole itself, bridging the two worlds. The whole structure, Dustin learns, is held together by a real scientific concept called 'exotic matter,' which is now the key to destroying the bridge and stopping Vecna.