Go further · Chapter 6 · 6a · Real-world case
Is the multiverse in films real physics?
The short answer (tap to open)
Film multiverses borrow from the Many-Worlds interpretation, one of several readings of quantum theory. In Many-Worlds every quantum outcome happens in its own branch, but branches never meet, nobody can travel between them, and they split on quantum events, not on choices. Films keep the idea that every possibility happens and change almost everything else.
What does Many-Worlds actually say?
In Hugh Everett's 1957 idea (page 6c), the universe has one wavefunction that never collapses. When a quantum measurement happens, every outcome occurs, each in its own branch, and a version of you in each branch sees one result. Decoherence (chapter 3) stops the branches interfering almost at once. It's a serious view, chosen by about 15% of physicists in 2025, but unproven, and one of many (chapter 6).
Where do films get it right?
- Every possibility happens somewhere. That's the heart of Many-Worlds.
- Each version of you experiences one world. Everything Everywhere All at Once (2022) and Dark Matter (2024) both build their stories on that feeling.
- The branches aren't all equal. Many-Worlds gives each branch a weight. Films don't, but the sense that some worlds are "more likely" than others has a real echo.
Where do they get it wrong?
- Travel and contact. In Marvel's multiverse films and most science fiction, people cross between worlds or meet their other selves. In Many-Worlds, branches can never interact again. There's no door.
- Choices. Films branch the world when a character makes a decision. In physics, branching follows quantum events. A choice only branches if some quantum event shaped it.
- Different laws and wildly different worlds. Films show worlds with hot-dog fingers or different histories from a single moment. Real branches start almost identical, and differ only where quantum events have different outcomes.
- Big objects in superposition. Dark Matter's box that holds a person in superposition contradicts decoherence. A warm human loses any blend almost instantly.
Physics or fiction?
Physics or fiction?
Fits Many-Worlds
Half fits
Fiction
Every outcome of a quantum event happens somewhere
The answers, in words
- Every outcome of a quantum event happens somewhere: Fits. That's Many-Worlds' central claim.
- You can visit a parallel world through a portal: Fiction. In Many-Worlds, branches can never interact again. There's no door.
- Your other self in another world can send you a message: Fiction. Once branches split they don't interact, so no messages.
- Choosing coffee over tea splits the universe: Half fits. Only if a quantum event shaped the choice.
- Each version of you feels like the only one: Fits. Each branch's observer sees one result.
- A machine lets you pick which world you end up in: Fiction. Nothing lets you choose your branch.
- Worlds differ wildly from a single moment's choice: Half fits. Branches drift apart slowly, from almost identical starts.
- A person can be kept in two states at once inside a box: Fiction. Decoherence. A warm human loses any blend almost instantly.
Why does this matter?
Films shape what millions of people think physics says. Knowing which parts come from a real interpretation, and which are storytelling, lets you enjoy both. And it's worth remembering that Many-Worlds is one option among the eleven in chapter 6 and page 6b.
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Films keep the 'every possibility' idea and invent the rest.
Real branches never meet, and they split on quantum events, not choices.
Next optional page · 6b
What do QBism, relational, consistent histories, ensemble and superdeterminism say?
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