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Quantum origin of time's arrow

Davide Romano

The problem of time’s arrow is (roughly) to understand why macroscopic physical processes typically evolve in a specific direction (the one we call “the future”) even though the underlying laws of physics describing the individual microscopic systems are time-reversal invariant. The standard answer to this problem is given by Boltzmann’s explanation of the II law of thermodynamics: a classical system starting in a non-equilibrium state spontaneously (i.e. with a high level of probability) tends towards equilibrium, thus implementing an irreversible process. However, this explanation has two drawbacks: 1. it needs a further assumption on the entropy of the initial state of the universe (past hypothesis); 2. microscopic systems (e.g. molecules in a box) should be represented as quantum states and not classical states. In this talk, I want to propose a different hypothesis to explain the origin of time’s arrow, based on quantum mechanics, specifically on decoherence theory. Differently from isolated systems, open quantum systems described by decoherence theory showirreversible behavior, as they evolve towards decoherence and von Neumann entropy increase. Is this behavior a sign of genuine irreversibility? And, if so, can this be linked to thermodynamic irreversibility?

Jun 21, 20240 citations

Geometric Origin of the Quantum–Classical Boundary and the Arrow of Time

涛翟

The quantum measurement problem and the arrow of time problem are two of the most fundamental unsolved problems in physics. This paper proves that they share the same geometric origin: the transition of the total information dissipation coefficient Υ from 0 to >0. Quantum collapse is a saddle-point bifurcation of Υ on a single quantum system — when the information dissipation channel opens, only a single classical saddle-point path survives among the quantum superposition states. Collapse and decoherence are not two independent processes but different stages of the same saddle-point bifurcation: decoherence is the early stage, and collapse is the late stage. The arrow of time is the macroscopic manifestation of Υ in statistical ensembles — irreversibility has two independent channels: Υ_E (energy dissipation, thermodynamic arrow) and Υ_φ (phase dissipation, information arrow). The two can be asynchronous: a pure dephasing system has Υ_φ>0 while Υ_E=0; collapse precedes thermalization. This independence yields testable predictions on cosmological scales: if the information arrow is activated before or after the thermodynamic arrow in the very early Universe, the primordial density fluctuations will retain distinct types of non-Gaussian features, whose shapes can be used to determine the activation order of the two channels. Foundational concepts of quantum mechanics — wave function, complex numbers, entanglement, decoherence, quantum–classical boundary — obtain a unified geometric definition within the order-parameter geometric framework. If experiments confirm that Υ_E and Υ_φ always change synchronously, or that log C(t) is linear rather than upward-curving, this theory is falsified.

Jul 26, 20260 citations

THE TIME. Arrow of Time Local Commitment, Cosmic Asymmetry, and the Principle of Super-Balance in Informational Monism

Ari Ariel Marom

The microscopic laws of closed quantum evolution do not distinguish past from future, yet experience does. The standard response traces this asymmetry to a low-entropy origin, derives from it a thermodynamic gradient, and treats the fixity of records as a corollary. That package supplies a direction — the side of time toward which entropy increases — but does not independently explain what it is for a part of history to be fixed while the remainder remains open. This monograph places temporal asymmetry within Informational Monism as a structured family of related operations rather than a single master fact. At the local level, measurement is an irreversible commitment: a record anchored by dissipation Σdiss≥kBln⁡2⋅Nrec\Sigma_{\mathrm{diss}}\ge k_B\ln2\cdot N_{\mathrm{rec}}Σdiss≥kBln2⋅Nrec is undone only with probability at most 2−Nrec2^{-N_{\mathrm{rec}}}2−Nrec. At the level of accessibility, fine-grained structure may remain conserved while becoming unreadable to resource-bounded observers. At the cosmic level, the Principle of Super-Balance is retained as an explicit anti-saturation postulate. The work does not derive the thermodynamic arrow, replace statistical mechanics, or offer new empirical predictions. It separates direction from status, quantifies the fixity of records, and states the costs and limits of the architecture with the same care as its claims. Keywords: arrow of time; irreversible records; Past Hypothesis; Landauer principle; fluctuation theorems; quantum complexity; Super-Balance; Informational Monism; thermodynamics of computation; foundations of physics

Oct 10, 20260 citations

Coherence, Entropy, and the Arrow of Time: Why Time Has a Direction in a Phase Ontology

Rob ten Napel

Coherence, Entropy, and the Arrow of Time: Why Time Has a Direction in a Phase Ontology (Phase Ontology — Part V) proposes a phase-centered explanation for one of physics’ strangest asymmetries: microscopic laws are largely time-symmetric, yet macroscopic reality is not. Cups shatter but do not reassemble; heat flows from hot to cold; correlations decay; memories accumulate. This paper argues that the arrow of time becomes conceptually clear once phase coherence is treated as ontologically primary. In this framework, time is not fundamental. It emerges operationally from countable phase evolution in physical clocks (all clocks are oscillators) and from synchronization between systems. A shared “global time” is therefore a relational structure sustained by coherence, not a background substance that governs dynamics. The paper then reframes entropy growth as the loss of accessible phase information in open systems. As systems interact with environments that contain many degrees of freedom, phase correlations disperse outward and become physically inaccessible, even if not destroyed in principle. Decoherence is elevated from a technical detail to the central engine of macroscopic irreversibility: reversing decoherence would require re-phasing an astronomically large environment, which is practically impossible. Building on Part III, the paper also interprets measurement as phase locking: once a macroscopic coupling stabilizes one local configuration, alternative phase possibilities are effectively dispersed into the environment. Classical definiteness and temporal irreversibility are thus treated as two faces of the same process—coherence flow. This manuscript is Part V of a seven-part series (Parts I–VII). It connects Parts I–IV to time asymmetry and points forward to Part VI (mass, inertia, gravitation) and Part VII (experimental implications and falsifiability).

Feb 15, 20260 citations

Reversible Quantum Control Is Not Time Reversal: Unitary Undoing vs. Irreversible Erasure and a Unified Taxonomy of Temporal Arrows

Luiz PUODZIUS

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** \((\Xi_{\mathrm{cr}})\), 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, \((\Xi_{\mathrm{cr}})\) captures the **rate of irreversible record overwriting**. In this formulation, entropy production obeys the lower bound\[\dot{S}_{\mathrm{irr}} \ge k_B \,\Xi_{\mathrm{cr}},\]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 \(\Xi_{\mathrm{cr}} > 0\). 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.

Apr 20, 20160 citations

Absolute Zero as Global Information Ground State: An Information-Theoretic Reconstruction of the Third Law of Thermodynamics

琼金黄

Abstract The third law of thermodynamics has two classical formulations: Nernst’s heat theorem (entropy change ΔS→0 as T→0) and the unattainability principle (absolute zero cannot be reached in a finite number of steps). Quantum statistical mechanics challenges Nernst’s theorem through residual entropy in systems such as quantum spin liquids and spin ice, which retain nonzero entropy even as T→0. Landauer’s principle connects information erasure with heat dissipation, implying that reaching absolute zero is equivalent to deleting all information from a system. This paper proposes that physical reality comprises two information-carrying sectors—the material phase (Ξ) and the information phase (Ω)—governed by strict conservation of total information. Within this framework, absolute zero is reinterpreted as the global information ground state of two-phase information settlement: it is both the absolute zero point of material-phase information capacity and the material embodiment of the minimal information potential of the information phase. Residual entropy is not an exception to the third law, but an inevitable manifestation of information conservation at the absolute zero boundary. Starting from the principle of least action incorporating two-phase coupling, we derive a quantitative condition for the unattainability of absolute zero and demonstrate that the decoherence rate of a quantum system near absolute zero is systematically modulated by the information-phase coupling parameter. The framework yields three testable predictions: a scaling relation between decoherence rate and information-phase coupling strength at ultra-low temperatures, entropy accumulation near quantum critical points corresponding to enhanced information-phase potential density, and a temperature scaling law for the coherence time of time crystals. This work unifies the third law of thermodynamics with quantum measurement, black hole information processing, dark energy cosmology, quantum entanglement, and the Higgs mechanism under a single cross-scale information settlement paradigm. Keywords: absolute zero, third law of thermodynamics, residual entropy, information conservation, Landauer’s principle, decoherence, quantum spin liquid, time crystal

Apr 16, 20260 citations

The Settlement Origin of the Arrow of Time: Two-Phase Information Conservation and the Emergence of Irreversibility

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The Settlement Origin of the Arrow of Time: Two-Phase Information Conservation and the Emergence of Irreversibility

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