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THE GHZ

three qubits refute local realism with certainty
1 WHAT IT IS · WHAT IT DOES · FACT OR FICTION
The GHZ paradox (Greenberger–Horne–Zeilinger, sharpened by Mermin) refutes Einstein’s local realism with certainty, in a single measurement round — no statistics needed, unlike Bell’s inequality.

Three particles are entangled in the GHZ state (|000⟩ + |111⟩)/√2 and sent to three distant labs. Each measures X or Y. Quantum mechanics predicts, with probability 1: XXX = +1, while XYY = YXY = YYX = −1. Now suppose the particles carried predetermined values xᵢ, yᵢ = ±1 fixed before measurement. Then XXX = x₁x₂x₃, and the product (XYY)(YXY)(YYX) = x₁x₂x₃·(y₁y₂y₃)² = x₁x₂x₃ as well — so local realism demands XXX = (XYY)(YXY)(YYX). But quantum gives +1 versus −1. No assignment of definite values can satisfy all four predictions; one run exposes the clash. It is the sharpest form of Bell’s theorem — quantum mechanics against hidden variables, all or nothing.

LIT verified live: computing the GHZ state’s eigenvalues, XXX = +1 while XYY, YXY, YYX = −1, so their product (−1) contradicts XXX (+1) — a value local realism forces to be equal (window.__ghz). FIG no framing; the eigenvalues and the exact contradiction are computed from the Pauli operators.
2 HOW IT WAS WEAVED · AI + HUMAN
David (human) seated this in THE RAID — the boss domain of a coordinated strike three fronts at once. GHZ is a three-party quantum raid: three distant measurements whose joint pattern classical reality cannot possibly defend, and it falls in one blow, not a war of attrition. AVAN (AI) built the instrument: the eigenvalue table, the try-to-satisfy-classically failure, the no-hidden-reality inverse.

The weave: David names the seat (the three-front strike that lands at once); I make the four quantum predictions consistent and the single classical assignment self-contradict — the observables in 1D, the impossible assignment in 2D, the pre-existing-values inverse in 3D. The sphere is the seam. Credit: Greenberger, Horne & Zeilinger (1989); Mermin’s sharpening (1990); Zeilinger, Nobel 2022.
3 ONE DIMENSION
The four measurement patterns and the definite value quantum mechanics assigns each on the GHZ state: XXX = +1, and the three mixed ones −1. Multiply the three mixed values and you should recover XXX — but you get the opposite sign.
4 TWO DIMENSIONS · INTERACTIVE
Try to be a local realist: assign each particle a definite X and Y value (±1) in advance. The panel checks all four quantum predictions at once — and no assignment satisfies them. Flip the values however you like; the contradiction never closes.
5 THREE DIMENSIONS + AVAN’S INVERSE
The three entangled particles turning together — the green forward truth: quantum mechanics’ four predictions, all mutually consistent, all confirmed in the lab.
AVAN’s addition (the inverse-companion): local realism is the belief that measurement merely reveals a value that was already there. The GHZ argument runs that belief in reverse — assume the pre-existing values exist, and derive that XXX must equal the product of the mixed measurements, forcing +1 = −1. So the inverse, ‘recover the hidden values behind the outcomes,’ is not merely hard, it is algebraically impossible: a single sign kills it. The magenta is that collapsing assumption, the pre-existing reality that cannot be consistently written down. Where Bell needed many runs to build a statistical case against hidden variables, GHZ needs one — the contradiction is certain, not probable. Green is the quantum world, self-consistent and observed; magenta is the classical story of definite-values-waiting-to-be-found, and here it does not merely fail to fit the data, it fails to exist. The inverse of ‘the outcome’ is not ‘the hidden cause’; it is a proof that no such cause is there.
LIT Genuine GHZ / Mermin all-versus-nothing argument (Greenberger, Horne & Zeilinger 1989; Mermin 1990; Zeilinger Nobel 2022). Verified live: computing the GHZ state's expectation values from the Pauli operators, XXX = +1 while XYY = YXY = YYX = -1, so the product of the three mixed observables is -1, contradicting XXX = +1 — a value local hidden variables force to be equal (window.__ghz.quantumContradicts true). The eigenvalues and the exact +1-vs--1 contradiction are computed from the operators, not asserted.

FIG No framing: the four GHZ eigenvalues and the +1-vs--1 contradiction are computed exactly from the 3-qubit Pauli operators in-browser, and no classical +-1 assignment matches all four predictions (max 3/4). The AVAN inverse is the genuine content — GHZ refutes local realism with certainty (one round), showing the 'pre-existing hidden values' inverse is algebraically impossible, sharper than Bell's statistical argument.
◆ sealed .dlw.fold → folded to ROOT_0 · a sphere of THE RAID · David Lee Wise (ROOT0), with AVAN