This is the demonstration layer of the Phase III central proposition of the research programme on the rigidity of geometric incidence. The predecessor framework supplies the quantum-measurement collapse arrow as a purely geometric datum — the causal structure and temporal orientability of Minkowski space — while keeping the global evolution unitary, and records the irreversibility of a measurement event as a causal monotone tied to the four-volume of the causal diamond between event and observer. The same data admit two readings: a geometric reading, in which the functional form of the irreversibility is rigidly determined by the modular geometry of the diamond (fixed up to an overall normalization) and is invariant under a change of geometry without recalibration; and an effective reading, in which the law is merely carried by a thermodynamic registration channel whose coefficient is free and must be recalibrated for each geometry. The paper poses the decision between them as a single theorem of empirical non-equivalence, built symmetrically so that either verdict — rigidity (new physics) or equivalence (reduction to einselection with an imported thermodynamic arrow) — would be a valid, publishable outcome. Working in algebraic quantum field theory, where the local algebras are type III₁, it establishes (on a reference state with geometric modular action — the vacuum, via Bisognano–Wichmann) that the irreversibility functional is determined by the diamond's modular data up to one normalization constant (Tomita–Takesaki, Casini–Huerta–Myers, Araki relative entropy), with the entire residual freedom localized in the modular status of the record-carrying state. Whether that normalization is itself geometric (the value π/24) is graded as a conjecture and is not load-bearing; the decisive content is invariance under a change of geometry, and the value is adjustable. In the genuine type III₁ continuum, both halves of the discriminating apparatus return a third verdict: the registered antisymmetric orientation is geometric and irreducible to any CPTP channel (in type III₁ there is no reduced density matrix to dilate, so no Stinespring dilation can readmit it "as only an ancilla"), yet it coincides with the Borchers–Wiesbrock spectral condition (energy positivity) — already-known QFT serving as the arrow, rather than a new irreducible mechanism. Any genuinely new positive is localized to two named sites: the interacting / non-geometric-flow sector (β ≠ 2π/a, where the Connes–Rovelli thermal-time reading must be rebutted, not assumed) and the orientation of the modular inclusion. A preregistered finite-N Gaussian discriminator returns equivalence in the simulable (type I) class — reported honestly as inconclusive for the fundamental reading, since the decisive type III₁ regime is not reached at any finite N. Scope: special-relativistic (Minkowski); gravity and quantum gravity are deferred. All results are explicitly graded (theorem / proposition / conjecture / computation / inherited), and the type III₁ instruments and verdict data are included with the deposit. Changes in v2 (2026-07-08). This version adds Phase IV, step 3 — the two-axis closure of the region left open by the free-sector verdict. Route (b), non-geometric Gaussian flow (multi-interval): the multi-interval vacuum modular flow is genuinely non-geometric (bilocal strength ρbi ∈ [0.004, 0.064]) yet carries a single modular temperature on every channel (D ≡ 0 at βmod = 1 to 10-12, continuum-stable), with the independent-scales einselection foil detected at D = 0.148 — NULL. Route (a), perturbative non-Gaussianity (tree-level λφ3): the T-odd connected cumulant onsets at first connected order (|A3| ∝ λ) but its separating content is zero (D = 0, dD/dλ = 0), while the multi-scale and FDT-breaking foils fire at 0.138 and 0.177 — NULL / recalibrable; the third verdict extends to the perturbative interacting sector. Both axes were pre-registered before running (frozen 2026-06-26 and 2026-06-25 respectively); no v1 result is altered. New verified references: Peschel (2003), Casini–Huerta (2009), Peschel–Eisler (2009), Arias–Casini–Huerta–Pontello (2018).
This is the demonstration layer of the Phase III central proposition of the research programme on the rigidity of geometric incidence. The predecessor framework supplies the quantum-measurement collapse arrow as a purely geometric datum — the causal structure and temporal orientability of Minkowski space — while keeping the global evolution unitary, and records the irreversibility of a measurement event as a causal monotone tied to the four-volume of the causal diamond between event and observer. The same data admit two readings: a geometric reading, in which the functional form of the irreversibility is rigidly determined by the modular geometry of the diamond (fixed up to an overall normalization) and is invariant under a change of geometry without recalibration; and an effective reading, in which the law is merely carried by a thermodynamic registration channel whose coefficient is free and must be recalibrated for each geometry. The paper poses the decision between them as a single theorem of empirical non-equivalence, built symmetrically so that either verdict — rigidity (new physics) or equivalence (reduction to einselection with an imported thermodynamic arrow) — would be a valid, publishable outcome. Working in algebraic quantum field theory, where the local algebras are type III₁, it establishes (on a reference state with geometric modular action — the vacuum, via Bisognano–Wichmann) that the irreversibility functional is determined by the diamond's modular data up to one normalization constant (Tomita–Takesaki, Casini–Huerta–Myers, Araki relative entropy), with the entire residual freedom localized in the modular status of the record-carrying state. Whether that normalization is itself geometric (the value π/24) is graded as a conjecture and is not load-bearing; the decisive content is invariance under a change of geometry, and the value is adjustable. In the genuine type III₁ continuum, both halves of the discriminating apparatus return a third verdict: the registered antisymmetric orientation is geometric and irreducible to any CPTP channel (in type III₁ there is no reduced density matrix to dilate, so no Stinespring dilation can readmit it "as only an ancilla"), yet it coincides with the Borchers–Wiesbrock spectral condition (energy positivity) — already-known QFT serving as the arrow, rather than a new irreducible mechanism. Any genuinely new positive is localized to two named sites: the interacting / non-geometric-flow sector (β ≠ 2π/a, where the Connes–Rovelli thermal-time reading must be rebutted, not assumed) and the orientation of the modular inclusion. A preregistered finite-N Gaussian discriminator returns equivalence in the simulable (type I) class — reported honestly as inconclusive for the fundamental reading, since the decisive type III₁ regime is not reached at any finite N. Scope: special-relativistic (Minkowski); gravity and quantum gravity are deferred. All results are explicitly graded (theorem / proposition / conjecture / computation / inherited), and the type III₁ instruments and verdict data are included with the deposit. Changes in v2 (2026-07-08). This version adds Phase IV, step 3 — the two-axis closure of the region left open by the free-sector verdict. Route (b), non-geometric Gaussian flow (multi-interval): the multi-interval vacuum modular flow is genuinely non-geometric (bilocal strength ρbi ∈ [0.004, 0.064]) yet carries a single modular temperature on every channel (D ≡ 0 at βmod = 1 to 10-12, continuum-stable), with the independent-scales einselection foil detected at D = 0.148 — NULL. Route (a), perturbative non-Gaussianity (tree-level λφ3): the T-odd connected cumulant onsets at first connected order (|A3| ∝ λ) but its separating content is zero (D = 0, dD/dλ = 0), while the multi-scale and FDT-breaking foils fire at 0.138 and 0.177 — NULL / recalibrable; the third verdict extends to the perturbative interacting sector. Both axes were pre-registered before running (frozen 2026-06-26 and 2026-06-25 respectively); no v1 result is altered. New verified references: Peschel (2003), Casini–Huerta (2009), Peschel–Eisler (2009), Arias–Casini–Huerta–Pontello (2018).
This synthesis condenses a multi-phase research programme on the geometric origin of the measurement arrow: whether the registered temporal orientation of a quantum measurement is irreducibly geometric or reducible to an effective (CPTP) channel. The question is converted into a theorem of empirical non-equivalence and computed where it can be decided — on a genuine type III₁ continuum object, outside the type I shadow in which the two readings provably coincide. The instrument returns a third verdict: the registered multi-time orientation is geometric and irreducible to any effective channel — in type III₁ the restricted state admits no density-matrix representation to dilate, so no Stinespring dilation can readmit it as "merely an ancilla," which excludes, within the stated framework, its reduction to einselection — and it simultaneously coincides with the Borchers–Wiesbrock spectral condition: the positivity of the energy rather than a new arrow, neither new physics nor an imported thermodynamic gradient. The frontier this verdict localized was then pursued with the same instrument across every in-scope regime it could reach — non-geometric flow, weak non-Gaussianity, integrable and genuine non-equilibrium, a fixed curved background, strong coupling, and a minimal quantum promotion of the geometry itself — and in every one the third verdict held: the registered orientation reduced to already-known structure (a single spectral temperature, a boost of one, an evolving Gibbons–Hawking temperature, or a functional of an effective dynamical background), with the apparatus repeatedly returning apparent positives that each dissolved under continuum and operator-level controls. A structural proposition accounts for the pattern and places any genuinely new positive outside every background-functional setting. At the one in-scope locus with no single background to reduce to — a geometry register that itself superposes and mediates between two matter parties — a first lattice measurement finds the joint multi-time record irreducible to any single shared effective classical background in its declared rival class, stably across three sizes: a record witness carrying information beyond the entanglement witness of the interferometric proposals, bounded to a figure of merit at lattice scope and grade (ii), with its field limit open. The aim of the document is documentary: every verdict is conditional on a declared chain of assumptions, every theorem and dataset lives in the companion phase records (DOIs below), and the vocabulary of decision names outcomes of preregistered, hash-frozen decision rules.
Phase IV closed the free/geometric-flow sector on the third verdict: the registered modular orientation is geometric and irreducible to any CPTP channel, yet it coincides with the Borchers–Wiesbrock spectral condition (energy positivity) — already-known QFT serving as the arrow. That verdict rests on a single structural fact: a KMS state has one modular temperature (Tomita–Takesaki). Any genuinely new arrow beyond the spectral condition therefore requires a state that is not KMS nor generalized-Gibbs. This paper attacks the one corner that is at once outside the third verdict, in scope (no gravity), and tractable: the current-carrying non-equilibrium steady state (NESS). Proceeding symmetrically, with preregistered decision rules frozen before any run: Island A (a Generalized Gibbs Ensemble after an integrable quench) closes null / horn b — the charge tower is absorbed by a single recalibration c(R) → 1, and a finite-size positive is diagnosed as a charge-basis conditioning artefact. The genuine NESS is decided in two stages. On the lattice, the preregistered instrument returns HORN A, grade (ii): the bulk-interval modular Hamiltonian is irreducible to the local-equilibrium-plus-current generator, with a clean law r∞ ≈ Δβ/2. A second, independently frozen preregistration takes the field limit a/β → 0 and returns global collapse: the decisive residual against the Bernard–Doyon boost-of-thermal reference vanishes as ~a² to the equilibrium floor across every drive, while the discriminator's teeth stay intact. The lattice HORN A is reclassified as a UV band-curvature (inflection-point) artefact; the growing distance-to-local-cone that produced it measures the intrinsic non-locality of the Cardy–Tonni boost-of-thermal entanglement Hamiltonian, a known-QFT feature, not new structure. The third verdict extends to the continuum non-KMS, positive-entropy-production sector. Any genuine new modular arrow is pushed to strongly-coupled / holographic NESS, named and left out of scope.
The second arc of the incidence–rigidity programme closed every tractableregime by one mechanism: a single effective background—a temperature, aboost, a generalized ensemble, a time-dependent profile—absorbs theregistered modular orientation, and the verdict reduces to the spectralcondition already in hand. The structural obstruction of Phase VI fixed theceiling for fixed backgrounds and left two exits; Phase VIII attackeddynamical geometry in its minimal lattice form, proved the blindnesstheorem—no single-time matter observable distinguishes quantum fromclassicalized geometry—and found that even the multi-time record of onematter sector collapses onto an effective background. This paper reportsthe continuation at the one locus that mechanism cannot reach byconstruction: a geometry that is itself in superposition, mediating betweentwo matter parties, where there is no single background to reduce to. Thetopology is the minimal Bose–Marletto–Vedral setup on a 1+1 lattice: twonon-interacting Ising chains coupled only through one quantum incidenceregister. Two layers are read off the same runs. Layer one is theentanglement witness as theorem and calibration: the mediatedlog-negativity grows to E_N = 0.124 while the fitted classical stochasticmediator of Kafri–Taylor–Milburn type, granted the quantum one-pointstatistics and full per-cell freedom, stays at the LOCC floor at every size(5.8e-11 to 6.4e-16)—and at the largest size it matches the quantum mutualinformation (0.042 vs 0.041) with negativity exactly zero. Layer two is theprogramme's question: is the joint multi-time record of the pair reducibleto any single shared effective background? Under a rule frozen by hashbefore the confirmatory tiers, two cells, (g, Ω) = (0.6, 1) and (0.6, 2),fire the record witness at Q = 13, 21 and 25 qubits—excesses +0.017 and+0.005 over a floor that saturates (0.0569 → 0.0666 → 0.0664), optimizerseed-scatter at 1e-16, Monte Carlo errors below every separation—while thefast-register row Ω = 4 collapses below the floor at all sizes: theadiabatic-elimination reduction of the earlier phases, recovered insidethis instrument as its null control. The verdict of the frozen rule isH1(record-discriminates): the joint record carries content irreducible tothe declared rival class, stably in size. The two witnesses dissociate inboth directions—more entanglement does not imply more record excess—so therecord defect is an information axis independent of the entanglementwitness, with its window where the mediator is a genuine dynamicalparticipant. The result is a graded lattice computation (grade (ii),minimal quantum-geometry sector); its deviations, calibrations and caveatsare reported in full, the field limit is left open, and the realinterferometric experiment is not modelled.
A relativistic framework in which the measurement event is modelled as a geometric incidence between a null quantum system (a photon, represented over projective null twistor space ℙN) and a timelike observer worldline in Minkowski space. The observer's forward temporal orientation is supplied not thermodynamically but as a discrete geometric datum fixed by the temporal orientability of Minkowski space. Global evolution remains unitary; the only irreversibility is a causal monotone of second-law type with no finite non-relativistic limit. The central claim — that the temporal arrow of collapse can be supplied purely geometrically while preserving unitarity — is stated as a falsifiable question with two valid answers, and the deciding experimentum crucis is specified but not yet executed. The claim is therefore left explicitly open.
Within orthodox quantum mechanics, the only empirical content of any physical claim is a change in the outcome statistics of a declared measurement. In the modern formulation of measurement theory this declaration is an instrument (a family of completely positive maps) or equivalently a POVM together with an implementation. In curved spacetimes, localized measurement theory supplies the appropriate notion of a “local interface”: a finite laboratory worldtube with finite switching, whose induced observables lie in the causal hull and whose instruments compose causally. This paper proves a closure result: for any declared localized measurement, all geometric dependence (metric, connection, curvature, horizons) can affect outcome statistics only through exactly two operational apertures: • Phase / support aperture: the implemented localized instrument or channel on the accessible algebra, including any differential proper‑time or propagation‑dependent phase and any geometry‑dependent support of the induced observable. • Entropy aperture: the accessibility restriction itself (restriction of the global state to the accessible algebra), equivalently a trace over inaccessible degrees of freedom, with the corresponding mixedness/entropy as the interface invariant. There is no third independent slot in the quantum‑mechanical probability rule into which “quantum gravity” can be inserted. Common‑mode phases are operationally null. Sub‑resolution “micro‑selection” is inadmissible without a refined POVM/instrument. And “mediator” talk without a mediator POVM is non‑identifiable, because Stinespring dilations are never unique. The closure is robust: within finite‑response classes, small perturbations of couplings or geometry produce proportionally small changes in outcome statistics. The result does not deny the possibility of new physics beyond orthodox QM. It eliminates a specific move that has repeatedly appeared in quantum‑gravity discourse: treating curvature as an additional, independently specifiable ingredient of orthodox quantum‑mechanical prediction at a local interface.
This manuscript establishes a mathematically controlled one-parameter modular-time coordinate for the vacuum representation of a free neutral scalar field on the right Rindler wedge. By restricting the state space strictly to the finite-entropy Weyl-coherent sector, the vacuum relative entropy is shown to be exactly quadratic based on rigorous external results by Longo and Casini–Grillo–Pontello. Consequently, the entropy Hessian exists without remainder estimates (O(t^3)), is strictly positive, and remains invariant under the modular group. By applying the Bisognano–Wichmann theorem, the modular parameter directly identifies with the Rindler boost rapidity up to orientation and the standard KMS-Unruh normalization (s = -2\pi\tau). The manuscript explicitly addresses the separate status of unbounded Araki perturbations (\phi(f)) and defines the exact boundary between proven theorems ([RIGOROUS]) and open matching hypotheses ([OPEN]), avoiding any completing-the-square assumptions for the modular Hamiltonian.