The relativistic quantum phase space (QPS) formalism extends classical phase space by incorporating both mean values and variance-covariance matrices of quantum states, thereby providing a unified setting where the uncertainty principle and relativistic covariance coexist. In this work we explore the basic geometric structure of the QPS for the signature \((1,4)\). We construct a scalar invariant built from the mean values and the inverse variance-covariance matrix, and prove its invariance under linear canonical transformations. For quantum states that saturate the uncertainty relations, and define the QPS itself, the invariant takes a value that encodes two fundamental length scales: a large scale characterising maximal coordinate uncertainties and a small scale characterising minimal coordinate uncertainties. From this invariance we derive a geometric equation that unifies the mean values and the quantum fluctuations. Analysing two asymptotic regimes reveals two physically significant limits: one leads to a curved spacetime geometry, consistent with current cosmological observations; the other yields a curved momenta space structure. These limits suggest a direct connection between quantum phase space geometry, cosmology, and quantum gravity, offering new perspectives on the origin of the quantum structure of spacetime. The results also resonate with the principle of Born reciprocity, which posits a fundamental duality between coordinates and momenta, and align with recent works on the relation between QPS and neutrino physics.
The relativistic quantum phase space (QPS) formalism extends classical phase space by incorporating both mean values and variance-covariance matrices of quantum states, thereby providing a unified setting where the uncertainty principle and relativistic covariance coexist. In this work we explore the basic geometric structure of the QPS for the signature ((1,4)). We construct a scalar invariant built from the mean values and the inverse variance-covariance matrix, and prove its invariance under linear canonical transformations. For quantum states that saturate the uncertainty relations, and define the QPS itself, the invariant takes a value that encodes two fundamental length scales: a large scale characterising maximal coordinate uncertainties and a small scale characterising minimal coordinate uncertainties. From this invariance we derive a geometric equation that unifies the mean values and the quantum fluctuations. Analysing two asymptotic regimes reveals two physically significant limits: one leads to a curved spacetime geometry, consistent with current cosmological observations; the other yields a curved momenta space structure. These limits suggest a direct connection between quantum phase space geometry, cosmology, and quantum gravity, offering new perspectives on the origin of the quantum structure of spacetime. The results also resonate with the principle of Born reciprocity, which posits a fundamental duality between coordinates and momenta, and align with recent works on the relation between QPS and neutrino physics.
This work addresses how classical-like behavior emerges in a relativistic quantum setting. Decoherence is described as the evolution of general quantum states belonging to a total state bundle toward a classical-like mixture of pointer states. The pointer states are geometrically supported by the relativistic quantum phase space (RQPS), defined as the subspace of the expectation-value space equipped with a ground variance field that saturates the uncertainty relations and satisfies an LCT-compatible de Sitter constraint.
Advances in the study of relativistic quantum phase space have established the set of Linear Canonical Transformations (LCTs) as a candidate for the fundamental symmetry group associated with relativistic quantum physics. In this framework, for a spacetime of signature (N+,N−), the symmetry of the relativistic quantum phase space is described by the LCT group, isomorphic to the symplectic Lie group Sp(2N+,2N−), which preserves the canonical commutation relations (CCRs) and treats spacetime coordinates and momenta operators on an equal footing. In this work, we investigate the contraction structure of the Lie algebra associated with the LCT group for signature (1,4), clarifying how familiar spacetime symmetry groups emerge from this more fundamental quantum phase space symmetry. Using the Inönü-Wigner group contraction formalism, we examine each limit case corresponding to the possible combinations of asymptotic values of two fundamental length scale parameters associated with the theory, namely a minimum length ℓ and a maximum length L, which may be identified respectively with the Planck length and the de Sitter radius. We explicitly analyze how contractions of the LCT Lie algebra lead to the physically relevant de Sitter algebra so(1,4) and, in the flat-curvature limit, to the Poincaré algebra iso(1,3) of four-dimensional spacetime. This provides an explicit mechanism through which relativistic spacetime symmetry can emerge from a deeper symplectic structure of quantum phase space.
This work addresses how classical-like behavior emerges in a relativistic quantum setting. Decoherence is described as the evolution of general quantum states belonging to a total state bundle toward a classical-like mixture of pointer states. The pointer states are geometrically supported by the relativistic quantum phase space (RQPS), defined as the subspace of the expectation-value space equipped with a ground variance field that saturates the uncertainty relations and satisfies an LCT-compatible de Sitter constraint.
The Heisenberg Uncertainty Principle is traditionally formulated within the mathematical idealization of perfectly flat Euclidean space. However, physical reality dictates thatspace is inherently curved by gravitational fields, cosmological dynamics, and perpetualquantum vacuum fluctuations. This paper proposes a novel theoretical framework that generalizes three fundamental uncertainty principles—Position-Momentum, Energy-Time, andAngle-Angular Momentum—by directly incorporating spatial curvature on a cosmologicalscale. We introduce a continuous spatial modulating function, f(x), governed by the netspatial curvature R(x), representing the dynamic interplay between attractive and repulsive geometric forces. To rigorously preserve the quantum mechanical axiom that physicalobservables correspond to Hermitian operators, we employ Weyl symmetrization to construct modified differential operators for momentum and angular momentum. Through exactmathematical derivations utilizing wave packet phase-space dynamics, a modified Ehrenfesttheorem, and the resolution of topological boundary discontinuities via mapping to a Universal Covering Space with strict Dirichlet boundary conditions, we establish absolute lowerbounds for these uncertainties. Ultimately, we demonstrate that the minimum bound ofquantum uncertainty is not a rigid universal constant, but is strictly positive and dynamically dictated by local geometric curvature, providing a robust bridge between quantummechanics and spacetime geometry.Keywords: Generalized Uncertainty Principle; Spatial Curvature; Weyl Symmetrization; Hermitian Operators; Modified Ehrenfest Theorem; Universal Covering Space; Cosmological Scale.PACSNumbers: 03.65.Ta(Foundationsof quantummechanics); 04.60.-m (Quantum gravity);03.65.Ca (Formalism).MSC2020 Codes: 81P05 (General and philosophical foundations of quantum mechanics);81S05 (Canonical quantization, commutation relations and statistics)
Recent developments in the unification of quantum mechanics and relativity have emphasized the necessity of generalizing classical phase space into a relativistic quantum phase space which is a framework that inherently incorporates the uncertainty principle and relativistic covariance. In this context, the present work considers the derivation of linear and quadratic Casimir operators corresponding to representations of the Linear Canonical Transformations (LCT) group associated with a five-dimensional spacetime of signature (1,4). This LCT group, which emerges naturally as the symmetry group of the relativistic quantum phase space, is isomorphic to the symplectic group Sp(2,8). The latter notably contains the de Sitter group SO(1,4) as a subgroup. This geometric setting provides a unified framework for extending the Standard Model of particle physics while incorporating cosmological features. Previous studies have shown that the LCT group admits both fermionic-like and bosonic-like representations. Within this framework, a novel classification of quarks and leptons, including sterile neutrinos, has also been proposed. In this work, we present a systematic derivation of the linear and quadratic Casimir operators associated with these representations, motivated by their fundamental role in the characterization of symmetry groups in physics. The construction is based on the relations between the LCT group and the pseudo-unitary group U(1,4). Three linears and three quadratics Casimir operators are identified: two corresponding to the fermionic-like representation, two to the bosonic-like representation, and two hybrid operators linking the two representations. The complete eigenvalue spectra and corresponding eigenstates for each operator are subsequently computed and identified
The absence of a common mathematical structure underlying quantum theory and relativistic physics remains a central obstacle to unification. While relativity is formulated in terms of spacetime geometry and covariance, quantum theory is intrinsically probabilistic, relying on amplitudes, uncertainty, and statistical interpretation. Existing unification programs typically attempt to quantize geometry or to geometrize quantum fields, but the probabilistic structure itself is rarely treated as a fundamental geometric object. In this paper, we propose a unified description of relativistic and quantum dynamics based on probabilistic geometry. Probability densities are taken as primary variables and are endowed with an intrinsic information–geometric structure defined by the Fisher–Rao metric. Within this framework, physical motion is described as the covariant evolution of probability distributions on a statistical manifold rather than as trajectories in a preassigned phase space or Hilbert space. The central result is a unified probabilistic–geometric field equation in which the relativistic d’Alembertian acting on the probability density is coupled to the scalar curvature of the associated information manifold. In an appropriate nonrelativistic limit, this equation reproduces the quantum potential as a curvature term, establishing a direct correspondence between quantum effects and informational geometry. Relativistic covariance is preserved throughout, allowing quantum and relativistic structures to appear as different regimes of a single probabilistic equation. The proposed framework does not introduce new particles, interactions, or quantization postulates. Instead, it provides a structural unification in which quantum and relativistic features emerge from the geometry of probability itself.