Exploratory paper in information geometry and local statistical reconstruction. This work studies the Fisher–Rao geometry induced by local probabilistic reconstruction frameworks and investigates a conditional variational extension. Revision note. In the initial version of the programme, causal structure was treated at the level of continuous reconstructive histories. In the revised architecture, Article 1 is restricted to its proper role: it establishes the local Fisher–Rao geometry of infinitesimal distinguishability between reconstructed states. Causal succession is not assumed at this stage. It is introduced later, in Article 17, where two states are defined as elementarily successive when the infimum of the reconstructive action connecting them equals the action quantum a0. Article 18 then shows, under explicit regularity assumptions, that the continuous histories used in Articles 5–6 arise as the variational continuum limit of such discrete causal chains.
Exploratory paper in information geometry and local statistical reconstruction. This work studies the Fisher–Rao geometry induced by local probabilistic reconstruction frameworks and investigates a conditional variational extension. Revision note. In the initial version of the programme, causal structure was treated at the level of continuous reconstructive histories. In the revised architecture, Article 1 is restricted to its proper role: it establishes the local Fisher–Rao geometry of infinitesimal distinguishability between reconstructed states. Causal succession is not assumed at this stage. It is introduced later, in Article 17, where two states are defined as elementarily successive when the infimum of the reconstructive action connecting them equals the action quantum a0. Article 18 then shows, under explicit regularity assumptions, that the continuous histories used in Articles 5–6 arise as the variational continuum limit of such discrete causal chains.
Discrete-to-Continuum Limit of Causal Chains in the Kähler Reconstruction Previous paper (Causal Reconstruction: Elementary Succession and the Planck Energy) proposed that the Schrödinger equation should arise as the continuum limit of discrete causal chains. Article 18 establishes this result under explicit regularity assumptions, completing the bridge between elementary causal succession and continuous quantum dynamics. Purpose The reconstruction programme contains two distinct transitions: Discrete causal chain → continuum reconstructive action → Madelung–Schrödinger dynamics. The second step was already established in Article 5. The purpose of this paper is to prove the first step: that discrete causal chains converge to the continuous reconstructive action in a mathematically controlled way. Main Idea The reconstructive cost between two states is interpreted as a discrete Lagrangian in the sense of variational integrator theory. A causal chain therefore becomes a discrete variational system whose dynamics is governed by discrete Euler–Lagrange equations. The key observation is that the discrete action SN = Σ C(ρk,ρk+1) plays exactly the role of a discrete Lagrangian approximation of the reconstructive action Srec. Main Results Discrete Lagrangian formulation. The reconstructive cost is shown to define a discrete Lagrangian under suitable regularity conditions. Discrete Euler–Lagrange equations. Critical causal chains satisfy discrete Euler–Lagrange equations expressing momentum continuity across each causal node. Γ-convergence. The discrete action SN Γ-converges to the continuous reconstructive action Srec as the elementary action quantum tends to zero while total duration remains fixed. Convergence of solutions. Solutions of the discrete causal-chain equations converge to solutions of the continuous Madelung equations. Preservation of Kähler structure. The discrete symplectic structure converges to the canonical Kähler symplectic form of the reconstruction phase space. Recovery of Schrödinger dynamics. Combining the present result with Article 5 yields a complete chain from discrete causal succession to the Schrödinger equation. Regularity Analysis A significant contribution of the paper is the analysis of the Fisher information functional in alternative coordinates. In the density variable ρ, Fisher information becomes singular as ρ approaches zero. In the amplitude variable u = √ρ, Fisher information becomes exactly a Dirichlet energy: I(ρ) = 4||∇u||². In the wavefunction variable ψ = √ρ exp(iS/ℏ), the reconstructive action becomes smooth on the natural Hilbert space H¹(M,C). This shows that the apparent singularities of Fisher information are coordinate artefacts rather than genuine obstructions. The Three Operative Conditions The continuum limit ultimately depends on three explicit conditions: C1 — Tightness: minimising sequences remain precompact. C2 — Small-step regime: elementary causal transitions remain inside the injectivity radius. C3 — Non-degeneracy: the second variation of the reconstructive action remains positive, excluding conjugate points and ensuring local uniqueness. Condition C2 becomes automatic in the continuum limit. Conditions C1 and C3 remain the principal analytical assumptions. Conceptual Significance The paper transforms the causal-chain picture from a heuristic interpretation into a variational approximation theorem. Discrete causal succession is no longer merely compatible with quantum dynamics; it converges to it. In this view, a quantum trajectory is not a fundamental continuous object. It is the continuum limit of a chain of elementary reconstructive transitions, each carrying one action quantum. Conclusion This paper completes the mathematical bridge between the causal layer and the quantum layer of the reconstruction programme. Under explicit regularity assumptions, discrete causal chains converge to the reconstructive action, the reconstructive action yields the Madelung equations, and the Madelung formulation is equivalent to Schrödinger dynamics. The resulting picture is a fully variational route from elementary causal succession to quantum mechanics.
The Reconstruction Theorem: Minimal Kähler Completion of Fisher–Rao Dynamics This article serves as a synthesis paper for the reconstruction programme. Rather than introducing new results, it identifies the programme's deductive core and compresses the results of Articles 1–11 into a single logical structure. Purpose The goal is to determine the minimal set of assumptions required to recover Madelung–Schrödinger dynamics from information-geometric principles. The paper distinguishes clearly between established results, conditional results, and open problems. The Five Hypotheses The reconstruction programme rests on five assumptions: H1: Reparametrisation invariance. H2: Markov monotonicity. H3: Cohesion (finite Fisher volume). H4: Compact reconstruction domain. H5: Variational selection by Fisher minimisation. H1 and H2 uniquely determine the Fisher–Rao geometry. H3 and H4 provide regularity. H5 remains a working variational principle whose justification is discussed elsewhere. Main Results Theorem A (Minimal Kähler Completion). The unique minimal admissible completion of the Fisher–Rao reconstruction space is the cotangent bundle T*P(M) equipped with its canonical symplectic structure and Kähler geometry. Through the Madelung map, this completion is isometric to the projective Hilbert space CP(L²(M)) endowed with the Fubini–Study metric. Theorem B (Coupling Uniqueness). The unique coupling compatible with Fisher geometry, Wasserstein dynamics, Kähler structure, and Markov monotonicity is λ = ℏ²/(8m). Corollary. Under the standard Madelung conditions (positive density and irrotational flow), the resulting dynamics is equivalent to the Schrödinger equation. The Deductive Kernel The article condenses the programme into a single chain: Fisher–Rao geometry + Wasserstein dynamics + canonical symplectic structure + minimal Kähler completion → Madelung–Schrödinger dynamics. Within this framework, the quantum structure appears as the unique admissible completion of the reconstruction dynamics rather than as an independent postulate. Three Explicit No-Go Results The existence of an action constant is forced by the symplectic completion, but its numerical value is not derived. Physical time is not obtained directly from H1–H5 and remains associated with the causal reconstruction layer. Gauge sectors are not derived from the present framework. Conclusion Article 12 functions as the logical charter of the reconstruction programme. Its main contribution is to identify the minimal deductive pathway leading from the Fisher–Rao reconstruction hypotheses to quantum dynamics, while explicitly separating established results from open problems.
We present the Effective Field Theory of Information Reconstruction (EFIR), a mathematically rigorous framework that unifies three foundational structures: variational field theory, Fisher–Rao information geometry, and open quantum system dynamics. The framework models observer-limited access to a latent information field I(x,t) through a gauge-invariant action functional, from which the field equation of motion is derived via the Euler–Lagrange formalism. A local rescaling symmetry is introduced to account for different observer frames, and the associated gauge field and covariant derivative are constructed explicitly. The observer's belief state is represented as a point on a statistical manifold equipped with the Fisher–Rao metric, evolving along geodesics driven by incoming observations. Uncertainty in the reconstruction process is quantified through a density operator whose dynamics follow the Lindblad master equation, derived from first-principles measurement back-action via Kraus operators. The three components — field, geometry, and quantum state — are coupled into a closed, well-posed dynamical system on the phase space M_EFIR = {I, θ, ρ}. A reconstruction tensor R_μν is derived from first principles and shown to satisfy a variance bound expressible in terms of the Fisher–Ricci scalar, establishing a direct link between information curvature and reconstruction noise. In the Gaussian limit, the framework reduces exactly to the Kalman–Bucy filter, providing a non-trivial consistency check against classical optimal filtering theory. For a network of N observers, the synchronisation cost is proven to scale as O(N²), and decoherence is shown to grow monotonically with observer density. The paper includes three independently falsifiable scaling laws, a complete simulation protocol validated on a two-qubit toy model, and a discussion of the connection to emergent gravity via the Hessian of the von Neumann entropy. Keywords: information field theory, Fisher–Rao geometry, open quantum systems, Lindblad equation, CPTP maps, Kraus operators, information reconstruction, Kalman–Bucy filter, multi-agent systems, emergent gravity, variational methods, gauge symmetry.
This paper extends the causal reconstruction programme from static optimal states to finite-action dynamical histories. A reconstructive history is modelled as a curve of probability measures in the mass-scaled Wasserstein space (P(M), W2,m), and admissible histories are selected by a reconstructive action combining a Wasserstein kinetic term, a Fisher information term, and a causal constraint. The resulting Euler–Lagrange equations form a coupled system: a continuity equation for the evolving density and a generalized Hamilton–Jacobi equation for the velocity potential. The central result is the Fisher–Bohm identity. For any sufficiently regular positive density ρ, the functional derivative of Fisher information satisfies δI / δρ(x) = -4 Δ√ρ / √ρ, so that the Bohm–Madelung quantum potential is exactly Q(x) = (ℏ2 / 8m) · δI / δρ(x). Thus the quantum potential is the Fisher information gradient of the probability density, scaled by ℏ2/8m. When the Fisher coupling in the reconstructive action is set to λ = ℏ2/8m, the Euler–Lagrange equations coincide with the Madelung equations and are therefore equivalent to the Schrödinger equation, under the standard assumptions of positive density and irrotational flow. This establishes a structural correspondence between reconstructive dynamics and non-relativistic quantum mechanics. The result is not presented as a derivation of quantum mechanics: the coupling λ = ℏ2/8m is matched through the Madelung Hamiltonian rather than derived from the reconstruction hypotheses. The geometric origin of this coupling remains an open problem.
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.
Why Fisher Geometry Gives Binary Born but Not Quantum Phase is the limitative companion to the conditional Born-rule derivation (osf.io/u5rde) within the Ignorant Observer Framework (IOF). The Born paper shows that finite-record Fisher–Rao geometry, together with two stated bridge assumptions, reconstructs the binary single-system Born weight p(θ) = cos²(θ/2). This paper proves the matching negative result: the same Markov-invariant, finite-record geometry that fixes that weight generates no quantum phase. The Fisher–Rao metric is real and phase-blind — nothing in finite-observer record geometry singles out the complex phase, or the relative phases that distinguish genuine quantum interference from a classical mixture. Two consequences follow. First, the reconstruction is honestly bounded: the binary Born weight is the Born structure native to a finite observer, while multi-outcome amplitudes, complex phase, and the full Hilbert-space formalism are hosted by the embedding rather than derived. Second, this limit is a feature, not a gap — it marks exactly where the finite-observer account stops and the ambient quantum formalism must be assumed, keeping the derivation's scope explicit. Part of the Ignorant Observer Framework (IOF): framework parent at osf.io/fcdsn, conditional Born-rule derivation at osf.io/u5rde.