We study irreversible response for coarse grained densities in Fisher-regularised quantum hydrodynamics, working within a local metriplectic framework. The state space, boundary class and a uniformly elliptic symmetric mobility G are fixed once and for all, and all constructions take place in the weighted H−1 ρ (G) geometry. Three instantaneous objects are singled out: the realised irreversible drift generated by G, a cost-entropy inequality that links control cost to entropy production, and a curvature coercivity bound on the Fisher functional. All three are invariant under the addition of any reversible drift generated by an antisymmetric operator J satisfying a weighted Liouville constraint. Equality in the cost-entropy bound picks out a one dimensional irreversible ray, and a simple "equality dial" quantifies the reversible content of a given evolution. Assumptions are minimal, convex free energy, strictly positive densities, symmetric uniformly elliptic G, and the H−1 ρ tangent model. All identities are supported by operational diagnostics and reproducible code. Read together with the companion paper, the present results identify the dissipative metriplectic channel compatible with the same Fisher geometry and Wasserstein-Otto tangent. The combined picture gives a minimal reversible-irreversible split for Fisher-regularised quantum hydrodynamics: the reversible current is the Fisher selected Schrödinger flow, while the present work fixes the local irreversible geometry and its equality and curvature certificates. A final scalar Fisher sector shows that the same weighted operator Lρ,G and Fisher quadratic form support a log density potential with a controlled Newtonian limit and a simple coupling to the Madelung Hamilton-Jacobi equation, kept deliberately within a scalar, weak field regime. All claims are necessity statements inside the stated axioms; no uniqueness of G or of the scalar dynamics is asserted beyond this local setting. The intended scope is quantum hydrodynamics and quantum information geometry for Fisher regularised Schrödinger dynamics with metriplectic dissipation.
We study irreversible response for coarse grained densities in Fisher-regularised quantum hydrodynamics, working within a local metriplectic framework. The state space, boundary class and a uniformly elliptic symmetric mobility G are fixed once and for all, and all constructions take place in the weighted H−1 ρ (G) geometry. Three instantaneous objects are singled out: the realised irreversible drift generated by G, a cost-entropy inequality that links control cost to entropy production, and a curvature coercivity bound on the Fisher functional. All three are invariant under the addition of any reversible drift generated by an antisymmetric operator J satisfying a weighted Liouville constraint. Equality in the cost-entropy bound picks out a one dimensional irreversible ray, and a simple "equality dial" quantifies the reversible content of a given evolution. Assumptions are minimal, convex free energy, strictly positive densities, symmetric uniformly elliptic G, and the H−1 ρ tangent model. All identities are supported by operational diagnostics and reproducible code. Read together with the companion paper, the present results identify the dissipative metriplectic channel compatible with the same Fisher geometry and Wasserstein-Otto tangent. The combined picture gives a minimal reversible-irreversible split for Fisher-regularised quantum hydrodynamics: the reversible current is the Fisher selected Schrödinger flow, while the present work fixes the local irreversible geometry and its equality and curvature certificates. A final scalar Fisher sector shows that the same weighted operator Lρ,G and Fisher quadratic form support a log density potential with a controlled Newtonian limit and a simple coupling to the Madelung Hamilton-Jacobi equation, kept deliberately within a scalar, weak field regime. All claims are necessity statements inside the stated axioms; no uniqueness of G or of the scalar dynamics is asserted beyond this local setting. The intended scope is quantum hydrodynamics and quantum information geometry for Fisher regularised Schrödinger dynamics with metriplectic dissipation.
We work in the universal information hydrodynamics (UIH) framework developed in two companion papers, where reversible quantum dynamics and irreversible response are organised in a local metriplectic geometry generated by a convex free energy, a Fisher metric, and an antisymmetric no work channel. In this setting the irreversible drift is always a Fisher gradient flow in a weighted H−1 geometry, equipped with a cost entropy inequality and a curvature coercivity bound that are invariant under the addition of any compatible reversible dynamics. In the present paper we show that this structure has a canonical realisation for Fokker Planck equations, finite Markov chains and GKLS semigroups, and that it can be reconstructed operationally from process and state tomography on real quantum hardware. First, starting from overdamped Langevin dynamics and its Fokker Planck generator, we identify a canonical Fisher Dirichlet operator G=Qdiag(π) that plays the role of the symmetric mobility on a periodic lattice and saturates the cost entropy inequality mode by mode. We then demonstrate that in a wide class of thermal and driven GKLS models the symmetric part of the real generator in the stationary BKM metric has a density block that coincides exactly with this classical Fisher operator, including nonreversible chains and random qubit and qutrit ensembles, and that the global decay of entropy and Fisher energy is governed by the Markov spectral gap while the Fisher gap controls only local curvature. Finally, we implement a suite of IBM Quantum experiments on a superconducting qubit that realises the full UIH picture on hardware. Process tomography of idle circuits yields an effective real generator K in the Pauli basis whose metric adjoint split in the BKM metric at the device stationary state produces a clean metriplectic decomposition K=G+J, with G metric symmetric and J metric skew. Independent idle depths are consistent with a single time homogeneous generator, the dissipative spectrum of G sets an information theoretic speed limit for BKM Fisher decay, and a curvature test shows that the same BKM metric is the local Hessian of quantum relative entropy at the stationary state. All claims are backed by a reproducible Python archive that includes constructive Fokker Planck to Markov to GKLS lifts, hypocoercive decay diagnostics, and hardware K tomography. Taken together, the results in this paper show that this programme is not only mathematically coherent, but experimentally visible, showing strong signatures of universality.
We pose the converse Madelung question: not whether Fisher information can reproduce quantum mechanics, but whether it is necessary. We work with minimal, physically motivated axioms on density and phase: locality, probability conservation, Euclidean invariance with a global phase symmetry, reversibility, and convex regularity. Within the resulting class of first order local Hamiltonian field theories, these axioms single out the canonical Poisson bracket on density and phase under the Dubrovin and Novikov assumptions for local hydrodynamic brackets. Using a pointwise, gauge covariant complex change of variables that maps density and phase to a single complex field, we show that the only convex, rotationally invariant, first derivative local functional of the density whose Euler Lagrange term yields a reversible completion that is exactly projectively linear is the Fisher functional. When its coefficient equals Planck constant squared divided by twice the mass, the dynamics reduce to the linear Schrodinger equation. For many body systems, a single local complex structure across sectors enforces the same relation species by species, fixing a single Planck constant. Galilean covariance appears through the Bargmann central extension, with the usual superselection consequences. Comparison with the Doebner and Goldin family identifies the reversible zero diffusion corner with linear Schrodinger dynamics. We provide operational falsifiers via residual diagnostics for the continuity and Hamilton Jacobi equations and report numerical minima at the Fisher scale that are invariant under Galilean boosts. In this setting, quantum mechanics emerges as a reversible fixed point of Fisher regularised information hydrodynamics. A code archive enables direct numerical checks, including a superposition stress test that preserves exact projective linearity within our axioms.
A mathematically explicit extension of quantum hydrodynamics is developed in which a scalar coherence field ΦG modifies phase transport and is driven by the information-geometric structure of the probability density together with probability transport itself. The construction starts from the Madelung representation Ψ = √ρ eiS/ℏ, augments the phase gradient by the covariant shift ∇S ↦ ∇S − αℏ∇ΦG, and defines the dynamics through a variational (ρ, S) sector together with a dissipative Onsager-type relaxation law for ΦG. This yields a closed PDE system consisting of a continuity equation, a modified Hamilton–Jacobi equation, and a coherence-field equation that reduces in the overdamped limit to an elliptic closure. The source of ΦG is neither bare mass density nor bare probability density: it is a local Fisher-information density together with probability transport, so that ΦG measures coherence demand. The field equations are written explicitly; the coupling sign is fixed by an energy-stability argument, the transport-forcing sign by a dissipation argument, and the induced coherence-pressure term is computed exactly. A structural no-signalling condition is obtained by restricting the nonlinearity to Fisher-marginal source functionals that are blind to the entanglement Fisher excess under marginalisation. A coarse-grained Yukawa sector is shown to admit a conditional Newtonian limit under explicitly stated screening and additivity assumptions; this remains a conjectural macroscopic regime rather than a completed derivation of gravity. The paper closes with a falsifiable numerical programme—ablation studies, dispersion diagnostics, Fisher-information monitoring, and an explicit pilot solver scaffold—together with a claim-status ledger, a testability map, and a development roadmap that separate what is defined, what is derived, what is heuristic, and what remains unproven. Keywords: quantum hydrodynamics; Fisher–Rao geometry; Madelung dynamics; coherence field; no-signalling; information geometry.
This work presents a reconstruction of quantum mechanics in which Schrödinger-type dynamics emerges from reversible probabilistic evolution rather than being postulated. Starting from a normalized probability density, we impose reversible probability dynamics, Fisher information geometry, and classical correspondence. These compatibility conditions yield coupled real equations equivalent to the continuity equation and the Hamilton–Jacobi equation with an additional information curvature (quantum potential) term. By combining density and phase into a complex amplitude, the Schrödinger equation appears as a compact encoding of reversible statistical flow. The result is mathematically equivalent to the Madelung hydrodynamic formulation and structurally connected to Bohmian mechanics, but derived without assuming Hilbert space, operator axioms, or measurement postulates. The work can therefore be viewed as an information-geometric derivation of quantum dynamics: quantum theory arises as the unique consistent representation of reversible probability flow. Keywords: quantum foundations, quantum reconstruction, emergent quantum mechanics, derivation of the Schrödinger equation, information geometry, Fisher information, Hamilton–Jacobi theory, Madelung formulation, Bohmian mechanics, reversible probability dynamics
This record contains Version 2.0 of The Schrödinger Equation from Capacity Geometry: General Forced-Action Theorem on a Fixed Capacity Background. Version 2.0 supersedes the earlier narrower local formulation (DOI: 10.5281/zenodo.19118007). The earlier record worked within a restricted quadratic-gradient density class. The present record proves the same result on the full local first-order homogeneous density class, with the weighted bulk-plus-flux bridge as the load-bearing structural principle rather than a minimality assumption on derivative order. The theorem lane is therefore broader, the claim boundaries are cleaner, and the companion-note dependence has been updated to reflect the current SGOC corpus. This record DOI. 10.5281/zenodo.19189901 should be treated as the source-of-record citation for the general fixed-background Schrödinger result. The paper proves a narrow but exact claim: within the full first-order homogeneous density class compatible with continuity-current structure, the Fisher-corrected Madelung action is the unique admissible action family up to the stated constant, and its Euler–Lagrange equations are exactly the Schrödinger equation. The decisive density correction is forced inside an upstream capacity-geometric theorem base rather than inserted by a diffusion or stochastic postulate. The logical scaffold is explicit and limited. Part 1A fixes the canonical logarithmic capacity scalar and the unique quadratic base tension. Parts 6 and 7A isolate the phase-blindness ceiling for the continuous quadratic sector. Part 6A sharpens the localisation-versus-smoothing and forced-balance framework. The present paper then shows that continuity-current compatibility fixes the phase sector, locality and first-order dependence force the full homogeneous density family, and a universal weighted bulk-plus-flux bridge with field-independent coefficients forces the Fisher form. The canonical member of that family is fixed by the bridge to the imported capacity scalar. In that precise sense the logical order at the Schrödinger layer is reversed: the geometric base comes first, and the Schrödinger action appears downstream of it. The claim is exact within its lane and no broader. This is a fixed-background, single-particle theorem stated away from nodal sets. It does not claim a many-body theory, a measurement theory, a relativistic completion, a full nodal-complement reconstruction theorem, or backreaction of the quantum sector on the background geometry. Appendix D records that on a nodal-complement component, once the phase-sensitive completion is an S¹-valued phase field, circulation quantisation and wavefunction reconstruction are automatic. Appendix G records a conditional H¹-closure lane inside the same fixed-background action. The discrete-curvature and branch-bookkeeping support used on nodal-complement triangulations belongs to the companion Closure Phase note, while the further complement-globalisation step belongs to the companion Relative Cohomology note. Keywords: Schrödinger equation; capacity geometry; Fisher information; Madelung action; phase-sensitive evolution; forced action; homogeneous density class; weighted Fisher bridge; REG; coherence scalar; fixed background; nodal complement; reproducibility Companion manuscripts cited in this paper's proof chain, from the SGOC programme: Part 1A: The Canonical Capacity Coordinate and the Unique Quadratic Tension in the Capacity Gauge. DOI: 10.5281/zenodo.19156316 Part 7A: The Second-Order Ceiling, Triadic Completion, and the Wilson-Triangle Lift. DOI: 10.5281/zenodo.19175902 Closure Phase as Discrete Curvature on a Triangulated 2-Complex. DOI: 10.5281/zenodo.19185885 Relative Cohomology and Cut-Graph Holonomy Trivialisation. DOI: 10.5281/zenodo.19185877 Additional provenance notes cited in the paper Part 6A: Localisation Rather than Saturation in Capacity Geometry: REG Dissipation, Forced Balance Laws, and a Restricted Ricci Bridge. DOI: 10.5281/zenodo.19174434 Landauer, Relative Entropy, and Fisher Length in Capacity Geometry. DOI: 10.5281/zenodo.19186309
Existing information-theoretic derivations of quantum mechanics from Fisher informationlack a thermodynamic embedding: they contain no temperature, no entropy, and no free-energy balance, and therefore cannot address the quantum–classical boundary within thesame variational structure. We show that this limitation is removed by a Helmholtz-typefree-energy functional on probability distributions in which Fisher information provides theenergy and relative Shannon entropy, weighted by an effective temperature ϑ, provides theentropic cost. Chentsov’s theorem and the Shore–Johnson axioms constrain this functionalup to two coefficients, one of which is fixed by consistency with the quantum kinetic energy.At ϑ= 0 the functional reproduces the Fisher-information variational principle of Reginattoand Hall–Reginatto; extremisation of the associated action recovers the Schr¨odinger equationvia the Madelung transformation. Quantum mechanics is thereby identified as the zero-temperature fixed point of the Helmholtz structure. The finite-temperature sector ϑ > 0,which has no counterpart in previous approaches, yields three results: a gauge-invariantbalance scale Lc = ℏ/2√mϑ at which both the free-energy descent and the gradient-flowspreading law change character — the spreading exponent crossing over from the quantum-pressure value 1/4 to the diffusive value 1/2 — together with, under harmonic confinement,a genuine variationally stable minimum interpolating between the exact quantum ground-state and classical equipartition widths; a dissipation bound for localisation transitions,derived from a Wasserstein gradient flow with Lyapunov structure, from which Landauer’sprinciple follows as a corollary in the entropy-dominated regime; and a thermodynamicstability property that singles out the Born weights as the unique stable basin fractionsunder the dissipative dynamics, presented as a consistency check.