The deep dive · one of eight answers to the same experiment

Superdeterminism

“The universe wrote your answers before you took the quiz.”

The loophole at the bottom of physics: what if nothing was ever free — including the experiments, the experimenters, and your decision to read this page?

"Don't open the door." You say it out loud, at the screen, like everyone in every row before you. She opens the door. She always opens the door — it was filmed a year ago; her choice has been sitting in the can, finished, since before you bought your ticket. It felt free to her, inside the scene. It was also already printed. Both true. No friction — that's just movies.

Here's the part that isn't: on the way out you pass the projection booth, and there's a second projector, older, lens pointed at the seats. Your gasp. Your "don't open it." Your ticket. Already developed.

Now shrink it.

The experiment that started all the trouble

Fire tiny particles at a wall with two slits, one at a time, with a screen behind it. One at a time matters: there's only ever one particle in flight. Common sense says each one goes through one slit or the other, and you get two piles. You don't get two piles. You get stripes — the pattern waves make when they ripple through both slits and overlap. So you put a detector at the slits to catch which one each particle uses. The stripes vanish. Two piles.

Everything on this page is one theory's answer to a single question: what, in the name of God, is going on between the gun and the screen?

Drag to orbit — two fingers on a touchscreen. Particles leave one at a time and land one at a time. The middle is deliberately not drawn — what happens there is the whole argument, and the lens is this theory's answer.

The idea

The famous "spooky" experiments all rest on one quiet assumption: that the experimenters could have chosen their settings freely. Deny that — let every choice, every particle, and every detector share one common cause at the beginning of time — and all the spookiness evaporates into bookkeeping. Nothing ever influenced anything faster than light. Nothing ever "happened" at all, really. Except once, at the start.

What it fixes

Everything, at the lowest possible price per universe and the highest possible price per everything else.

What it costs

If choices are secretly correlated with what's being measured, then controlled experiments stop being evidence — anywhere, for anything, forever. Including the experiments that might have supported superdeterminism. It doesn't lose arguments. It dissolves the concept of arguing.

The story

Every famous "spooky" quantum result leans on one assumption so natural nobody thought to put it on the poster: that the experimenters could have chosen otherwise. [[bell]]'s theorem — the proof that quantum correlations can't come from ordinary shared history — quietly requires that your choice of measurement settings is independent of the particles being measured. Bell knew this. He said, on the record, that if that independence fails — if the choices and the particles were correlated all along — the whole spooky edifice "collapses into an innocent-looking determinism."

That escape hatch is superdeterminism. Wind every particle, every detector, every twitch of every experimenter's thumb back far enough and they share one origin. Let the correlations be set there — at the initial conditions of the universe — and nothing nonlocal ever needs to happen. No spooky action, no dice, no branching. Just one enormous, airtight unfolding, in which the "free choices" that make experiments feel like interrogations of nature were always part of the same script as the answers.

It is not a crowded field, but it is not empty: Gerard 't Hooft — an actual Nobel laureate — has spent years building deterministic models underneath quantum mechanics, and a handful of serious physicists argue the loophole deserves real investigation rather than eye-rolling. The eye-rolling, meanwhile, has been industrial-scale. In 2016, a hundred thousand people worldwide mashed buttons in a browser game to generate measurement settings from human whim; quantum weirdness won anyway. Other teams chose settings using starlight from quasars, fixed billions of years before Earth. Won anyway. The loophole now requires the conspiracy to include your gamer thumbs and light older than the planet. Superdeterminists reply, correctly, that this changes nothing: initial conditions don't care how baroque you make the test, and were never going to.

The real bill isn't physics, it's method: if experimental choices are secretly correlated with what's being examined, then controlled trials stop being evidence — anywhere, for anything, forever. Including the evidence for superdeterminism. Its critics call that self-immolating. Its friends call it the price of the only interpretation with no spookiness, no extra worlds, and no dice. You'll have your own reaction. You were always going to.

The argument

“You've abolished the scientific method itself.”: I've noticed an assumption it was resting on. Not my fault nobody checked the foundations before building the cathedral.
“A cosmic conspiracy coordinating particles, detectors, and your thumbs is absurd.”: "Conspiracy" is what you call a correlation you find rude. I call it initial conditions. The universe only had to be arranged once — and it demonstrably was arranged somehow.
“There's no possible evidence for your position!”: Correct. Nor against it. I understand your frustration completely — I understood it before you arrived.

The experiment

The Big Bell Test and quasar-light Bell tests · 2016-2018

In 2016 physicists recruited 100,000 strangers to mash random buttons, live, worldwide, and used the mashing to choose detector settings. Quantum weirdness won anyway. Another version chose settings using light from quasars — fixed billions of years before Earth existed. Also won. So your loophole now requires the universe to have conspired using both gamer thumbs and ancient starlight. You're fine with this. You were always going to be.

100,000 human choosers; then light from distant quasars

The books

No book can help you; it was always going to be this way. Read Beyond Weird by Philip Ball anyway. You were always going to.

Your neighbors

Many-Worlds — the other fully deterministic picture — every history instead of exactly one.
Pilot Wave — your fellow hidden-variable theory — theirs pays in nonlocality what yours pays in freedom.

← all theories

Glossary 24 terms

wavefunction

The mathematical object that assigns a complex number to every possible configuration of a system.

Written ψ. It is not a wave in space like a ripple on a pond — for two particles it lives in a six-dimensional configuration space, not in the room. Whether ψ is a real physical thing or a bookkeeping device for what you know is precisely what the interpretations argue about.