Fundamental physical laws are unitary and reversible, yet observed physical phenomena exhibit irreversibility, thermality, entropy increase, and horizon radiation. Reconciling this apparent contradiction remains a central problem in modern theoretical physics. This work introduces a unified geometric framework, termed selection geometry, in which irreversibility emerges naturally from non-invertible selection acting on projective Hilbert space. We show that physical states are naturally represented as points in projective Hilbert space, whose compactified structure introduces a geometric point at infinity analogous to conformal boundaries in spacetime and the Riemann sphere. Selection mapping acts as a non-invertible projection, compressing spectral degrees of freedom and producing a realized state manifold that is spectrally non-closed. This spectral non-closure provides a geometric origin for thermality, entropy increase, and Hawking radiation. Thermality emerges from circular Euclidean time geometry and the KMS condition, while horizon radiation arises from horizon-induced spectral selection. Event horizons act as selection surfaces that restrict accessible spectral degrees of freedom while preserving global spectral completeness. Within this framework, global spectral evolution remains unitary and reversible, while realized evolution becomes irreversible due to geometric quotient structure induced by selection. This dual structure resolves the black hole information paradox by distinguishing global spectral completeness from realized spectral accessibility. Selection mapping is physically realized as completely positive trace-preserving (CPTP) evolution on density operators. Irreversibility therefore emerges not from dynamical law violation, but from geometric structure. This work establishes selection geometry as a foundational geometric principle underlying quantum mechanics, thermodynamics, and gravitational physics.
Fundamental physical laws are unitary and reversible, yet observed physical phenomena exhibit irreversibility, thermality, entropy increase, and horizon radiation. Reconciling this apparent contradiction remains a central problem in modern theoretical physics. This work introduces a unified geometric framework, termed selection geometry, in which irreversibility emerges naturally from non-invertible selection acting on projective Hilbert space. We show that physical states are naturally represented as points in projective Hilbert space, whose compactified structure introduces a geometric point at infinity analogous to conformal boundaries in spacetime and the Riemann sphere. Selection mapping acts as a non-invertible projection, compressing spectral degrees of freedom and producing a realized state manifold that is spectrally non-closed. This spectral non-closure provides a geometric origin for thermality, entropy increase, and Hawking radiation. Thermality emerges from circular Euclidean time geometry and the KMS condition, while horizon radiation arises from horizon-induced spectral selection. Event horizons act as selection surfaces that restrict accessible spectral degrees of freedom while preserving global spectral completeness. Within this framework, global spectral evolution remains unitary and reversible, while realized evolution becomes irreversible due to geometric quotient structure induced by selection. This dual structure resolves the black hole information paradox by distinguishing global spectral completeness from realized spectral accessibility. Selection mapping is physically realized as completely positive trace-preserving (CPTP) evolution on density operators. Irreversibility therefore emerges not from dynamical law violation, but from geometric structure. This work establishes selection geometry as a foundational geometric principle underlying quantum mechanics, thermodynamics, and gravitational physics.
This note develops a first mathematical toy implementation of Selection Geometry. Selection Geometry proposes that observed physical reality is not exhausted by globally unitary dynamics alone, but arises through observer-dependent realization acting on a larger coherent possibility structure. In this framework, physical states are represented on projective Hilbert space, while realized history appears through a non-invertible selection map that restricts accessibility and compresses distinguishability. The resulting realized sector is spectrally non-closed: globally coherent structure is not destroyed, but is no longer fully accessible within the local realized description. This geometric non-closure provides a unified structural perspective on irreversibility, entropy increase, thermality-like behavior, and horizon phenomena. In particular, horizons are interpreted as selection surfaces at which accessibility changes and globally distinct spectral degrees of freedom become locally compressed. Global evolution remains unitary and reversible, whereas realized evolution becomes effectively irreversible due to the geometry of accessibility reduction. The purpose of this paper is foundational rather than exhaustive. It introduces the core geometric principle, defines the distinction between global possibility and realized history, and clarifies how selection surfaces and spectral non-closure provide a common language for the arrow of time, thermal structure, and horizon-associated radiation. The work does not yet offer a complete dynamical implementation of selection, but establishes the conceptual and geometric basis on which later mathematical toy models and further physical developments can be constructed.
Standard quantum mechanics suffers from unresolved measurement problem and preferred basis problem. Furthermore, there exists a fundamental incompatibility between the quantum formalism constructed on Hilbert spaces and general relativity formulated on four-dimensional spacetime manifolds. In this paper we propose a new quantum interpretation: Global Hilbert-space Boundary-selected Projection Interpretation (GHS-BSI). We postulate that the only fundamental physical reality is the global Hilbert space of a closed universe and its universal quantum state , which satisfies the Wheeler–DeWitt equation and undergoes exclusive unitary evolution, with no physical wavefunction collapse. Four-dimensional Lorentzian spacetime, together with all material fields and interactions, emerges as the orthogonal spectral projection of the universal quantum state onto closed linear subspaces of the global Hilbert space. Spacetime boundary itself is a product of quantum projection, acting as an intrinsic constraint operator to filter quantum subspaces: only quantum branches that can form causally consistent four-dimensional spacetime become observable physical reality, and no parallel worlds exist. We complete the topological mathematical refinement of the boundary selection operator, strictly derive Einstein’s field equations from the distribution of projection weights, resolve the preferred basis problem common to all projection-based interpretations, and revise a series of observable predictions to prioritize prominent signatures detectable with existing datasets. Without introducing extra dimensions or hidden variables, GHS-BSI naturally unifies quantum correlations and relativistic spacetime geometry. It remains empirically consistent with the core conclusions of orthodox quantum mechanics and general relativity, while providing a unified ontological foundation and falsifiable observational predictions for both fundamental theories. Keywords: quantum foundations; measurement problem; global Hilbert space; spectral projection; boundary selection; spacetime emergence; unification of quantum mechanics and relativity; observable predictions
Abstract The ontological status of time remains unresolved in fundamental physics. In quantum mechanics, time appears as an external classical parameter, whereas in general relativity it is dynamical and intertwined with spacetime geometry. Canonical approaches to quantum gravity, most notably the Wheeler–DeWitt formulation, eliminate time altogether, leading to the well-known “problem of time.” These tensions motivate frameworks in which time is not fundamental but emergent. In this work, we propose a discrete, update-based framework in which the universe evolves through a sequence of global quantum states indexed by an abstract update parameter rather than by a physical time coordinate. Evolution is formulated as a completely positive, trace-preserving (CPTP) quantum channel acting on the universal density operator, ensuring exact conservation of probability and global quantum information at every update. The framework is deliberately conservative: it preserves the formal structure of quantum mechanics and quantum field theory, enforces vacuum stability, and supports global conservation laws without introducing new dynamical postulates. Within this setting, time emerges relationally at the level of subsystems. As subsystems become increasingly entangled with their environments, entropy gradients arise that define an effective arrow of time, closely aligned with the thermodynamic arrow. The resulting temporal flow is relative, statistical, and observer-dependent, while the global evolution remains information-preserving and, in the closed-system limit, reversible. We explore the implications of this framework for cosmology and black hole physics. The Big Bang is reinterpreted as an initial quantum state rather than a singular beginning of time, avoiding temporal singularities. Black hole evaporation is shown to be compatible with unitary evolution when the full quantum state is considered, naturally reproducing the expected Page curve and resolving the apparent information paradox. Overall, the framework provides a coherent, minimal setting in which time, irreversibility, and cosmological history emerge from quantum correlations rather than from a fundamental temporal background.
This work introduces projection geometry as a minimal, purely geometric framework for understanding the fundamental limits of physical measurement. Modeling observation as a measurable projection from a system state space to an observable space, the paper shows that non-invertibility of this projection generically obstructs the existence of invertible observable dynamics—even when the underlying system evolves deterministically and invertibly. The results are derived using only basic assumptions about measurable spaces, projection maps, and physical interfaces, without invoking probability theory, quantum postulates, or statistical ensembles at the level of the obstruction. A central theorem demonstrates that, for generic (non fiber-preserving) dynamics, no consistent invertible evolution can be defined on observable states. The framework is supported by a set of objective facts drawn from geometry, physics, perception, and information theory, highlighting the roles of dimensional reduction, finite resolution, and selective coupling. These structural constraints imply that physical measurement is universally non-invertible: multiple distinct system states are operationally indistinguishable through any physically realizable interface. This perspective provides a unified geometric account of information loss, irreversibility, and observer dependence, and suggests that features often associated with quantum theory—such as apparent state collapse and operational equivalence—may arise as consequences of projection-induced non-invertibility.
We develop a pre-geometric reconstruction framework in which quantum mechanics, entanglement structure, gauge symmetry, locality, Lorentzian spacetime geometry, gravitation, and physical constants emerge from recursively stabilized coherent Hilbert-relational organization. The framework begins from a primitive coherent substrate consisting of compositional accessibility relations and complex transport amplitudes. No background spacetime manifold, metric geometry, or particle ontology is assumed fundamentally. The central proposal is that coherent Hilbert structure is more fundamental than spacetime geometry. Observable spacetime emerges through projection stabilization: a physical stability-selection mechanism dynamically selecting recursively stable coherent sectors from deeper relational structure. Quantum mechanics emerges from norm-preserving coherent transport. Entanglement emerges from nonfactorizable relational closure. Gauge symmetry emerges as redundancy of coherent transport representation. Classicality emerges through decoherence and stability selection. Lorentzian geometry emerges statistically from projected accessibility organization. Gravitation emerges thermodynamically as equilibrium relaxation of projected geometry. The framework is presented not as a completed unified theory, but as a reconstruction program aimed at explaining why physical reality organizes itself through Hilbert structure, gauge redundancy, locality, spacetime geometry, and thermodynamic gravitational dynamics.
The foundations of modern theoretical physics rest on the interplay between quantum dynamics, thermodynamics, and spacetime geometry. While quantum mechanics describes microscopic dynamics through unitary time evolution, thermodynamic phenomena introduce irreversibility and entropy production. In this work we propose a unified framework in which quantum evolution is formulated on a complex-time manifold that naturally incorporates both dynamical and thermodynamic structures. We introduce a complex-time coordinate combining physical time and thermal flow and derive a generalized evolution equation from a variational principle defined on a complex-time geometric manifold. The resulting equation contains both Hamiltonian dynamics and geometric diffusion terms governed by the Laplace–Beltrami operator. This formulation provides a geometric interpretation of thermodynamic irreversibility within quantum theory and establishes connections with Euclidean quantum field theory, geometric quantum mechanics, and thermal time hypotheses. Possible implications for quantum statistical mechanics and information flow in gravitational systems are discussed.