The spectral formulation of dynamics, based on self-adjoint structural operators, allows organizing the evolution of physical systems in terms of independent eigenmodes. However, the spectral decomposition, although mathematically complete, does not provide, by itself, a criterion of physical admissibility. In this work, a variational principle is introduced in the space of structural operators, in the form of a spectral functional whose stationarity condition imposes restrictions on the spectrum. It is shown that physical admissibility must be formulated as a spectral selection problem, in which only specific subsets of eigenvalues are compatible with conditions of structural stability. It is demonstrated that spectral decomposition does not determine the admissibility of the structure, and that the introduction of an independent variational criterion leads to non-trivial relations between the eigenvalues of the operator. As a consequence, it is obtained that admissibility implies spectral restrictions, establishing a direct connection between the operatorial organization of dynamics and underlying variational principles. The scope of the work is strictly structural. A direct identification between eigenvalues and specific physical quantities is not established, nor is a complete phenomenological theory proposed. The objective is to determine the minimum level at which physical selection can be formulated as a consequence of spectral properties and stability criteria.
The spectral formulation of dynamics, based on self-adjoint structural operators, allows organizing the evolution of physical systems in terms of independent eigenmodes. However, the spectral decomposition, although mathematically complete, does not provide, by itself, a criterion of physical admissibility. In this work, a variational principle is introduced in the space of structural operators, in the form of a spectral functional whose stationarity condition imposes restrictions on the spectrum. It is shown that physical admissibility must be formulated as a spectral selection problem, in which only specific subsets of eigenvalues are compatible with conditions of structural stability. It is demonstrated that spectral decomposition does not determine the admissibility of the structure, and that the introduction of an independent variational criterion leads to non-trivial relations between the eigenvalues of the operator. As a consequence, it is obtained that admissibility implies spectral restrictions, establishing a direct connection between the operatorial organization of dynamics and underlying variational principles. The scope of the work is strictly structural. A direct identification between eigenvalues and specific physical quantities is not established, nor is a complete phenomenological theory proposed. The objective is to determine the minimum level at which physical selection can be formulated as a consequence of spectral properties and stability criteria.
We present a structural formulation of physical dynamics in which temporal evolution is described by a unitary propagation operator W^=f(H^), defined from a self-adjoint structural operator H^. In this context, dynamics is not primarily introduced by differential equations or continuous sums over trajectories but is characterized by the spectral structure of the propagation operator. It is shown that the spectral decomposition of H^ induces an organization of the evolution into independent modes, each governed by a spectral factor f(λn). The unitarity of W^ implies that these factors admit a phase representation, leading to a modal description in terms of spectral phases. It is further demonstrated that frequency emerges as a well-defined spectral function associated with the temporal variation of the phase of each mode. Additionally, it is established that dynamical quantities can be formulated as spectral functions of the eigenvalues of H^, providing a minimal spectral dictionary in which phase, frequency, and dynamical scales are defined intrinsically to the formalism. The results obtained are strictly structural and do not involve the introduction of external phenomenological hypotheses. In particular, this work does not establish a direct identification between eigenvalues and specific physical quantities, nor does it construct a complete theory of interactions or measurement. It is concluded that the spectral structure of the propagation operator provides the minimum level at which dynamics can be organized, establishing a formal basis for the development of future extensions of the formalism toward the description of specific physical systems.
We present a structural formulation of physical propagation in which dynamics are described by a unitary operator W^=f(H^), associated with a self-adjoint structural operator H^, and by its bilocal representation W(x,y). Time evolution is formulated as the iterative application of this operator, without assuming differential equations as a fundamental starting point. It is shown that the spectral decomposition of H^ induces a complete organization of the evolution into independent eigenmodes, each governed by a spectral factor f(λn). From this structure, it is demonstrated that the bilocal propagation kernel is entirely reconstructed from the spectrum and the eigenvector basis of the structural operator. In the regime of translational homogeneity, it is proven that the propagation operator is diagonalizable in a basis compatible with translations, resulting in the absence of mixing between spectral modes. Outside this regime, it is shown that the support of the kernel W(x,y) completely determines the connectivity of propagation, while its off-diagonal structure encodes relations between distinct nodal states. Additionally, it is established that quantities defined as functions of the structural operator can be evaluated directly in the spectral basis, providing an intrinsic characterization of the dynamics in terms of the spectrum of H^. The results obtained do not constitute a complete physical theory nor do they establish a direct identification between the operator's spectrum and specific empirical observables. The objective of this work is to make explicit the structural level at which propagation is organized by unitary operators and by their spectral decomposition, providing a coherent basis for further developments.
We present a structural formulation of physical dynamics based on discrete unitary propagation, in which the time evolution is directly described by a unitary operator W^=f(H^) associated with a self-adjoint structural operator H^. Starting from the relationship between action and phase, ϕ=S/ℏ, and the variational construction of structural operators, we show that the propagation can be written exactly as the action of a bilocal kernel W(x,y) on the state, in continuity with recent developments of the Action-Phase program. We show that the spectral decomposition of H^ induces a diagonalization of the unitary propagation, in which the state evolution becomes multiplicative in the eigenvector basis of the structural operator. Consequently, the spectral structure organizes the propagation modes of the system, providing a description in which the dynamics is expressed in a decoupled manner between modes. It is evidenced that the distinction between nodal representation and spectral representation emerges naturally from the operator structure, corresponding to different decompositions of the same state in distinct bases of the same Hilbert space. In the case of translational invariance, the decomposition into Fourier modes is recovered as a particular situation. The results presented do not constitute a complete reconstruction of quantum mechanics nor a general gravitational theory. In particular, aspects of measurement, multiparticle structures, or complete covariant formulations are not treated. The objective of this work is more restricted and precise: to establish a formulation in which the dynamics is determined by the propagation operator and organized by its spectral decomposition, providing a structural layer from which more complete physical descriptions can be developed.
We present a structural formulation of physical dynamics in which time evolution is directly described by a unitary propagation operator, rather than being primarily introduced by continuous differential equations. Starting from the relationship between action and phase, ϕ=S/ℏ, and the variational construction of self-adjoint structural operators, it is shown that propagation can be exactly expressed through a bilocal kernel W(x,y) associated with an operator W^=f(H^), with H^=H^†. We demonstrate that the structural homogeneity of the kernel, characterized by the condition W(x,y)=W(x−y), implies the spectral diagonalization of the propagation operator. In this regime, the evolution becomes decoupled between modes, and the absence of spectral mixing provides a minimal structural expression of conservation. It is further shown that the off-diagonal structure of the bilocal kernel completely determines the connectivity of propagation between states, allowing the effective locality of the dynamics to be characterized in terms of the support of W(x,y). The analysis establishes, in a controlled manner, the relationship between the bilocal description and the Lagrangian formulation, indicating that the operatorial structure replaces, at the considered level, the need for a continuous sum over trajectories, without excluding its recovery as an effective limit in appropriate regimes. The obtained results show that dynamics can be entirely organized in terms of the propagation operator and its spectral decomposition, in which the nodal representation and the spectral representation emerge as complementary descriptions of the same structure. The scope of this work is strictly structural: it does not propose a complete reconstruction of quantum mechanics, nor a general gravitational theory, nor a formulation for multiparticle systems or measurement processes. The objective is to establish a minimal layer in which physical propagation is encoded by the unitary operator and its spectral structure.
This work addresses the structural problem of defining physical observables in regimes where the spectral decomposition of self-adjoint operators is not purely discrete. In particular, it is demonstrated that, outside the ultraviolet regime, the identification between mass and eigenvalues ceases to be consistent when the associated spectral measure has a continuous component. Starting exclusively from minimal spectral hypotheses -- self - adjoint operator, resolvent, spectral measure, and its density -- it is established, without resorting to ad hoc hypotheses, that the observable physical structure is determined by the spectral measure associated with the state. As a consequence, it is proven that the physical dimension of a system is not given by the dimension of the Hilbert space nor by the cardinality of the spectrum, but by the structure of the dominant spectral regions of the density, defining the notion of effective spectral dimension. In this framework, physical observables emerge as functionals of the spectral measure. In particular, mass is characterized as the first-order spectral moment, while the spectral width quantifies the dispersion associated with the energy distribution. It is further shown that dominant spectral regions act as effective degrees of freedom, providing a distributed description of the dynamics. The developed formalism recovers the discrete limit of quantum mechanics, is compatible with the spectral representation of quantum field theory, and admits a natural interpretation in terms of scale flow. Explicit falsifiability criteria are also established, and the structural limitations of the proposed framework are delineated. The central result is the formulation of a principle: physical dimension and observables emerge from the effective spectral structure, implying the necessary substitution of pointlike descriptions with distributed descriptions in non-discrete regimes.
On the Admissible Geometry of Physical Motion: Courant–Fischer Spectral Reduction, Self-Adjoint Transport, and the Reinterpretation of Randomness, Probability, and Superposition In this 90-page paper, we present a unified operator-theoretic framework for understanding physical motion across transport, stability, and quantum systems. Drawing from the mathematical lineage of Newton, Euler, Lagrange, Sturm–Liouville, Rayleigh–Ritz, Courant–Fischer, Koiter, and Schrödinger operator theory, the work argues that physically realized motion does not occupy the full formally accessible configuration space, but instead evolves only within admissible spectral manifolds selected by variational and self-adjoint operator geometry. We also develop a rigorous variational formulation in which entropy geometry, denoted by the field (S(x,t)), acts not as a classical measure of disorder, but as a geometric admissibility structure governing spectral realization. Within this framework, probability and superposition are not removed from physics, but are reinterpreted as residual structures supported on reduced admissible manifolds. The resulting operator law demonstrates that realized transport fields may be represented by a dramatically smaller number of admissible eigenmodes than the full numerical or statistical state-space traditionally assumed in classical stochastic transport theory. Using NASA Curiosity Radiation Assessment Detector (RAD) datasets from the Mars Science Laboratory cruise phase, the paper demonstrates that high-dimensional radiation transport repeatedly collapses into low-dimensional coherent occupancy structures. Spectral occupancy analysis reveals that realized transport concentrates into a small number of dominant admissible modes, implying that radiative motion is geometrically confined rather than broadly distributed across accessible LET space. These findings are interpreted through the mathematical structures of Sturm–Liouville spectral theory, Courant–Fischer minimax admissibility, Rayleigh–Ritz variational reduction, and Schrödinger localization theory. The manuscript further integrates nonlinear stability theory through the work of W. T. Koiter, demonstrating that admissibility restriction is already deeply embedded throughout classical continuum mechanics. By analyzing positive-definite energy functionals, second-variation structures, and admissible deformation manifolds, the paper shows that physical systems naturally restrict realizable motion through energetic geometry before probabilistic interpretation ever arises. This establishes a direct mathematical bridge between variational stability theory, operator localization, and constrained transport evolution. One of the central contributions of the work is the reinterpretation of randomness itself. Rather than treating randomness as a primitive ontological feature of nature, the paper proposes that randomness corresponds to unresolved or non-admissible geometric structure within the governing operator manifold. Under this interpretation, probability measures are supported only on admissible spectral sectors selected by self-adjoint variational evolution. The framework therefore unifies deterministic motion and residual probabilistic structure within a single operator-theoretic formulation. The work also consolidates and mathematically contextualizes a broader body of empirical investigations previously conducted by the authors across industrial CFD transport systems, structured heat transport, Navier–Stokes regularity, and quantum measurement theory. Across these independent physical domains, the same geometric phenomenon repeatedly emerged: the effective dimensionality of realized motion was dramatically smaller than the formally accessible state-space. The present paper provides the variational and spectral-theoretic explanation for this recurring empirical confinement structure. More broadly, the paper proposes that the history of mathematical physics has always implicitly pointed toward admissibility-constrained motion. From Newtonian mechanics and Hamiltonian conservation laws to Sturm–Liouville spectral realization, Rayleigh–Ritz minimization, Koiter stability theory, and Schrödinger operator localization, physical systems repeatedly evolve through constrained operator geometries rather than unconstrained stochastic occupation of all accessible states. The present work synthesizes these mathematical traditions into a unified framework suggesting that the reduction of probability space through admissible spectral geometry may constitute one of the foundational organizing principles underlying physical reality itself. At its deepest level, the paper argues that admissibility has always been the hidden organizing principle connecting the evolution of physical motion across seemingly disconnected domains of science. Newtonian trajectories are admissible paths determined by force geometry. Hamiltonian evolution confines motion to conserved energetic manifolds. Sturm–Liouville systems admit only boundary-compatible eigenfunctions. Rayleigh–Ritz and Galerkin theory restrict realizable solutions to admissible variational subspaces. Koiter stability theory permits only energetically realizable deformation fields. Schrödinger evolution itself unfolds within self-adjoint spectral sectors. The present framework identifies these not as isolated mathematical techniques, but as manifestations of a single underlying principle governing realized physical motion. Within this interpretation, the distinction traditionally drawn between classical determinism and quantum probability becomes substantially reduced. Classical mechanics, transport theory, elasticity, turbulence, and quantum evolution all emerge as different realizations of admissible operator evolution constrained by geometry, stability, and spectral realization. Probability therefore does not fundamentally replace determinism at microscopic scales; rather, residual probability appears precisely where admissibility geometry becomes unresolved, incomplete, or only partially observable within the governing operator manifold. The framework consequently proposes that deterministic evolution and probabilistic realization are not contradictory descriptions of nature, but different manifestations of the same underlying admissibility structure. The larger implication is the possibility of a unified theory of motion grounded not in unconstrained state enumeration, but in admissible spectral geometry itself. Across radiation transport, fluid mechanics, stability theory, quantum localization, thermodynamic transport, and variational mechanics, the same recurring mathematical structure appears: realized motion occupies only a reduced admissible manifold selected through self-adjoint variational evolution. The paper therefore suggests that the long-standing separation between classical and quantum descriptions of motion may ultimately be resolved through a unified operator-theoretic framework in which admissibility, rather than stochastic occupation, governs the evolution of physical systems across all scales of reality.