Stranger Things Season 5's Exotic Matter Has A Basis In Real-World Physics

Spoilers ahead for "Stranger Things" season 5, volume 2.

The Upside Down looks a bit different in "Stranger Things" season 5. Now, there's a military lab stationed inside it, along with a massive, fleshy wall that forms a perimeter of sorts. In "Chapter Five: Shock jock," Dustin (Gaten Matarazzo), Steve (Joe Keery), Jonathan (Charlie Heaton), and Nancy (Natalia Dyer) head to the Upside Down's version of the Hawkins Department of Energy in the hopes of finding answers. Recalling the force field around the second Death Star in "Star Wars: Episode VI — Return of the Jedi," Dustin deduces that the flesh wall is Vecna's (Jamie Campbell Bower) shield, so a "shield generator" must be nearby. After a lot of back and forth, Nancy shoots at a strange light that she and Jonathan spot in the sky, assuming it's what they're looking for.

This serves as an effective cliffhanger leading into "Chapter Six: Escape from Camazotz." There, Dustin finally reveals what he's learned from Dr. Brenner's (Matthew Modine) journal. As it turns out, Vecna's shield is made of something known as Exotic Matter, which is why it doesn't work the same way an energy shield does. He also reveals that the Upside Down is a wormhole and not a separate mirror dimension. (A most Stephen King-y twist indeed.) For whatever reason, this wormhole has been stable since its creation, forming a bridge between Hawkins and a world dubbed the Abyss. With Nancy having inadvertently destabilized the Exotic Matter wall, it implodes and starts consuming everything in its path.

While Dustin doesn't really explain it, the term "Exotic Matter" wasn't invented for "Stranger Things." Rather, it's a scientific label used by real-life physicists to describe matter with odd properties.  But what does it actually mean, and how is it connected to wormholes?

Matter usually takes one of three states (solid, liquid, or gas), but matter that doesn't behave like any of these states or exhibits uncommon properties is called Exotic Matter. You might've heard of dark matter, which can only be understood in hypothetical terms, as it isn't composed of the standard electron-proton-neutron makeup. Another example is superfluid helium, which is basically liquid helium exposed to extremely cold temperatures. Once this temperature change happens, it does things that liquids cannot usually do, like climb walls or dribble upwards.

Per Albert Einstein's theory of relativity, we know that matter can bend space, which explains the existence of wormholes that can bend space-time. One type of Exotic Matter related to wormholes is matter with negative mass, which repels other forms of matter away from it. Physicist Kip Thorne has proposed that negative matter is necessary for a wormhole to remain stable, as this stability allows it to act as a bridge between two different points. While there's no way to prove this (it's a theoretical hypothesis, after all), "Stranger Things" might be operating on the notion that Vecna is using the properties of Exotic Matter to keep the Upside Down stable.

This would mean that the flesh wall is made up of matter with negative mass, causing it (and the wormhole) to act in inexplicable ways that defy provable scientific theory. As negative matter has a speculative connection to the concept of time travel (!), "Stranger Things" could use it to justify moving forward or backward in time as soon as the wormhole collapses. Hopefully, such a twist will justify everything the series has been working towards since 2016.

The "Stranger Things" series finale will debut on December 31, 2025, on Netflix.