The emergence of a single, coherent classical world requires more than a macroscopic arrow of time. While irreversible record formation establishes temporal ordering, it does not by itself ensure that macroscopic histories remain mutually consistent rather than fragmenting into incompatible configurations. We study a minimal network-based model in which local records accumulate irreversibly, generating time but not necessarily global coherence. We show that, in the absence of a consistency-restoring mechanism, macroscopic states fragment even under causal dynamics. Introducing constraint restoration stabilizes coherence; critically, this restoration need not be diffusive, acausal, or globally optimized. A single, strictly local, finite-speed constraint update per timestep suffices to suppress inconsistency, even on adversarial frustrated graphs and as system size increases. These results identify local constraint restoration as a minimal structural requirement for macroscopic coherence under irreversibility, and provide a concrete instantiation of the Coherence–Selection Interface Theory framework for selection under constraint [10]. Keywords: arrow of time, irreversibility, macroscopic coherence, decoherence, consistent histories, graph Laplacian, local constraint restoration
The emergence of a single, coherent classical world requires more than a macroscopic arrow of time. While irreversible record formation establishes temporal ordering, it does not by itself ensure that macroscopic histories remain mutually consistent rather than fragmenting into incompatible configurations. We study a minimal network-based model in which local records accumulate irreversibly, generating time but not necessarily global coherence. We show that, in the absence of a consistency-restoring mechanism, macroscopic states fragment even under causal dynamics. Introducing constraint restoration stabilizes coherence; critically, this restoration need not be diffusive, acausal, or globally optimized. A single, strictly local, finite-speed constraint update per timestep suffices to suppress inconsistency, even on adversarial frustrated graphs and as system size increases. These results identify local constraint restoration as a minimal structural requirement for macroscopic coherence under irreversibility, and provide a concrete instantiation of the Coherence–Selection Interface Theory framework for selection under constraint [10]. Keywords: arrow of time, irreversibility, macroscopic coherence, decoherence, consistent histories, graph Laplacian, local constraint restoration
Decoherence and thermodynamic irreversibility are widely regarded as sufficient to explain the emergence of classical behavior from quantum mechanics. Decoherence suppresses interference between branches of the wavefunction, while entropy production provides a direction to macroscopic time. However, neither mechanism alone explains why macroscopic physics exhibits a single, persistent, globally consistent classical history rather than fragmentation into mutually incompatible record sets. In this work, we identify and formalize this unresolved issue as the classicality gap. We show that in finite systems subject to nonzero noise and irreversible record formation, decoherence and entropy production are generically insufficient to stabilize a single coherent macroscopic history. Instead, absent a history-level selection mechanism, redundant records diverge and macroscopic identity becomes ill-defined. We present a general instability result demonstrating this fragmentation tendency and introduce history-level constraint restoration as the minimal structural mechanism capable of preventing it. This mechanism operates without new microdynamics, collapse postulates, or observer dependence. We derive qualitative phase boundaries separating stable and unstable regimes and propose concrete experimental protocols on NISQ-era quantum platforms that can falsify the necessity of history selection. Our results establish that persistent classicality is not guaranteed by decoherence alone, but requires selection acting on histories under irreversible constraints. Keywords: classicality emergence, decoherence limits, record inconsistency, history instability, quantum-to-classical transition, irreversibility, entropy production, information persistence, open quantum systems, foundations of physics
The macroscopic arrow of time is commonly attributed to irreversibility, yet many theoretical treatments implicitly assume time as a primitive parameter even when discussing emergent temporal behavior. In this work, we study a minimal framework in which time is not presupposed but arises operationally from irreversible record formation. We show that the existence of persistent, non-erasing records is sufficient to induce a monotone, reparameterization-invariant ordering of events, independent of microscopic dynamics or background time parametrization. Using a minimal concrete realization, we explicitly demonstrate monotonicity, reparameterization invariance, and the breakdown of temporal ordering when irreversibility is relaxed. We do not address relativistic or quantum time directly; rather, we isolate the minimal structural requirements for temporal ordering to exist at all. Taken together with companion work on coherence stabilization, these results support a modular view of emergent classicality in which time and coherence arise from distinct physical mechanisms. Keywords: emergent time, irreversibility, records, relational time, arrow of time, foundations of physics
The quantum measurement problem is commonly framed as a tension between unitary microscopic dynamics and the appearance of definite macroscopic outcomes. Decoherence theory explains the suppression of interference but does not explain why a single, persistent outcome is realized rather than a superposition of mutually incompatible macroscopic records. Interpretive responses—including collapse models, many-worlds branching, and observer-centric accounts—add ontological or epistemic structure beyond standard quantum mechanics. In this work, we show that such supplementation is unnecessary. We demonstrate that decoherence alone is generically insufficient to stabilize consistent macroscopic measurement histories under irreversible record formation. We introduce history-level coherence selection as a minimal structural requirement for persistent outcomes. This mechanism operates without modifying unitary dynamics, introducing collapse postulates, or invoking observers. We show that measurement outcomes correspond to stable, selection-supported histories rather than instantaneous state reductions. This reframing resolves the measurement problem by identifying the missing macroscopic mechanism—history selection under irreversible constraint—rather than by altering quantum theory. Keywords: quantum measurement problem, history selection, decoherence insufficiency, classical records, interpretation of quantum mechanics, consistent histories, irreversibility, information flow, foundational physics, measurement theory
Quantum Darwinism explains the emergence of objective classical reality through redundant proliferation of information into the environment. While successful in symmetric, weakly noisy settings, the framework implicitly assumes that redundancy alone guarantees macroscopic stability. In this work, we demonstrate that redundancy and decoherence are insufficient to stabilize classical outcomes in the presence of irreversible record formation, asymmetric noise, or heterogeneous constraints. We introduce coherence selection as a distinct macroscopic mechanism operating at the level of histories rather than instantaneous states. Coherence selection acts as a structural filter on admissible histories, favoring those that maintain mutual consistency among redundant records under irreversible constraint. We show that Quantum Darwinism emerges as a special symmetric limit of this broader framework. Outside that limit, coherence selection is required to prevent fragmentation of macroscopic records. We identify regimes where coherence, rather than energy or entropy, dominates macroscopic outcomes, derive qualitative stability criteria, and propose falsifiable experimental tests. These results elevate coherence selection from a descriptive framework to a necessary macroscopic mechanism underlying persistent classicality.
The emergence of a stable, classical world from the underlying quantum reality is a central puzzle of modern physics. While decoherence explains the suppression of quantum interference, it does not, by itself, explain the selection of specific, robust classical histories. Here, we present a complete, end-to-end theory for the emergence of classicality, grounded in the thermodynamics of irreversible record-formation and testable on current-generation quantum computers. We first derive a consistent, directed temporal order from thermodynamic principles, resolving known issues with relational time concepts. We then argue that the coherence of histories within this emergent time is unstable to noise unless actively stabilized by a local, error-correcting-like mechanism. We formalize this mechanism as a projection onto a constrained subspace of the history Hilbert space and argue for its stability for a general class of noise models. Finally, we map this mechanism onto the dynamics of a 2D lattice of superconducting qubits, where the constraints are identified with the stabilizers of the surface code. We derive an analytic expression for the phase boundary between stable and unstable regimes, validate it with illustrative calculations based on the analytic theory, and propose a specific experiment on a trapped-ion quantum computer to test a unique, falsifiable power-spectrum signature. This work bridges the gap between foundational theory and experimental reality, providing a concrete, testable mechanism for the emergence of classicality.
We present a unified operational framework for the arrow of time grounded in irreversible information loss. While microscopic physical laws are time-reversal invariant, macroscopic irreversibility arises when systems overwrite metastable records. We show that recent reversible quantum-control experiments do not reverse time, but instead operate in regimes where no logically irreversible record is created. To formalize this, we introduce the **forgetting rate** (Ξcr), a coarse-grained rate defined on physically selected metastable record states (e.g., pointer states, memory registers, or macroscopic configurations). Unlike standard entropy production, which is expressed in terms of microscopic transition asymmetry, (Ξcr) captures the **rate of irreversible record overwriting**. In this formulation, entropy production obeys the lower boundS˙irr≥kBΞcr,consistent with Landauer's principle but expressed at the level of record dynamics. Within this framework, thermodynamic, quantum-measurement, psychological, and cosmological arrows emerge as substrate-dependent manifestations of Ξcr>0. Temporal asymmetry is therefore not a single global property, but a distributed feature of physical information-processing systems. The approach naturally explains the decoupling of arrows in composite systems and identifies experimentally accessible regimes where irreversibility can be locally suppressed. This work does not introduce a new microscopic law but provides a unifying, operational reformulation that connects information thermodynamics, decoherence theory, and memory dynamics through a single coarse-grained rate.