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arXiv:quant-ph/0104067

Hidden Variables, Statistical Mechanics and the Early Universe

Antony Valentini

Published Apr 13, 2001• 14 citations
arXivHTMLPDF

Abstract

It is argued that our universe happens to be in a state of statistical equilibrium at the hidden-variable level, such that nonlocality is masked by quantum noise. To account for this 'quantum equilibrium', we outline a subquantum statistical mechanics in configuration space, and an H-theorem analogous to the classical coarse-graining H-theorem. Foundational issues in statistical mechanics are addressed, and an alternative explanation based on 'typicality' is criticised. An estimate is given for the relaxation timescale, and an illustrative numerical simulation is provided. Assuming the universe began in quantum non-equilibrium, we sketch a scenario in which relaxation is suppressed at very early times by the rapid expansion of space, raising the possibility that deviations from quantum theory could survive to the present day for relic cosmological particles that decoupled sufficiently early. It is concluded that quantum noise is a remnant of the big bang and, like the microwave background, should be probed experimentally. Possible tests with relic particles are briefly discussed.

DOI
10.48550/arxiv.quant-ph/0104067

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It is argued that our universe happens to be in a state of statistical equilibrium at the hidden-variable level, such that nonlocality is masked by quantum noise. To account for this 'quantum equilibrium', we outline a subquantum statistical mechanics in configuration space, and an H-theorem analogous to the classical coarse-graining H-theorem. Foundational issues in statistical mechanics are addressed, and an alternative explanation based on 'typicality' is criticised. An estimate is given for the relaxation timescale, and an illustrative numerical simulation is provided. Assuming the universe began in quantum non-equilibrium, we sketch a scenario in which relaxation is suppressed at very early times by the rapid expansion of space, raising the possibility that deviations from quantum theory could survive to the present day for relic cosmological particles that decoupled sufficiently early. It is concluded that quantum noise is a remnant of the big bang and, like the microwave background, should be probed experimentally. Possible tests with relic particles are briefly discussed.
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Quantum mechanics is a highly successful fundamental theory which has passed every experimental test to date. Yet standard quantum mechanics fails to provide an adequate description of measurement processes, which has long been rationalized with operationalist and positivist philosophical arguments but is nevertheless a serious shortfall in a fundamental theory. In this dissertation we introduce quantum mechanics with a discussion of the measurement problem. We then review the de Broglie-Bohm pilot-wave formulation, a nonlocal hidden-variables theory where the state of a quantum system is described by a configuration (independent of measurements) in addition to the wave function, and we apply it to fundamental problems concerning black holes and the early universe.\nIn de Broglie-Bohm theory, general initial conditions allow for deviations from the statistical predictions of standard quantum mechanics. We review how the Born rule can be understood as the result of an equilibration process for systems with sufficient mixing before proceeding to study the implications of quantum nonequilibrium in various physical contexts.\nIn this work we show that small perturbations to a system are themselves insufficient to drive relaxation to quantum equilibrium even over very long timescales. This has implications for the potential survival of nonequilibrium in relic particles, and renders it unlikely that field perturbations can be driven to equilibrium by small corrections to the Bunch-Davies vacuum during inflation, allowing for the possible detection of imprints of nonequilibrium in the cosmic microwave background. Using a simple model we also demonstrate how quantum nonequilibrium can propagate nonlocally through entanglement, providing a mechanism for information flow from black holes. This opens up a possible path to the resolution of the black hole information paradox by allowing for information to be released in hidden variable degrees of freedom during black hole evaporation. Finally, we consider whether features in the angular power spectrum of temperature anisotropies in the cosmic microwave background radiation could arise from quantum nonequilibrium initial conditions. Preliminary results indicate that this approach can provide a natural explanation for the power deficit anomaly at large angular scales, as well as oscillatory features in the same regime.
In a fundamental formulation of the quantum mechanics of a closed system such as the universe as a whole, three forms of information are needed to make predictions for the probabilities of alternative time histories of the closed system . These are the action functional of the elementary particles, the quantum istate of the universe, and the description of our specific history. We discuss the origin of the "quasiclassical realm" of familiar experience and Hamiltonian quantum mechanics with its preferred time in such a formulation of quantum cosmology. It is argued that these features of the universe are not general properties of quantum theory, but rather approximate features that are emergent after the Planck time as a consequence of theories of the closed system's quantum state and dynamics.
We discuss several proposals for astrophysical and cosmological tests of quantum theory. The tests are motivated by deterministic hidden-variables theories, and in particular by the view that quantum physics is merely an effective theory of an equilibrium state. The proposed tests involve searching for nonequilibrium violations of quantum theory in: primordial inflaton fluctuations imprinted on the cosmic microwave background, relic cosmological particles, Hawking radiation, photons with entangled partners inside black holes, neutrino oscillations and particles from very distant sources.
Description: This work explores the conditions under which quantum superposition may emerge or persist at cosmological scales, challenging the common assumption that the early universe was the most favorable environment for quantum coherence. While the universe is widely believed to have originated from a quantum regime, the extreme interaction density, thermal noise, and intense field couplings of the early universe are argued to have caused rapid decoherence, effectively suppressing sustained quantum superposition beyond minimal scales. In this sense, the early universe is interpreted as a decoherence-dominated environment rather than a coherent quantum domain. The paper proposes an alternative perspective in which the late universe, characterized by cosmic expansion, reduced interaction density, and lower environmental noise, may offer more favorable conditions for partial isolation and the re-emergence of quantum superposition under specific circumstances. This conceptual framework reframes the quantum–classical transition as an environmentally driven process rather than a purely temporal or scale-dependent one, contributing to ongoing discussions in quantum cosmology, decoherence theory, and the foundations of physics. 🔹 Keywords: Quantum cosmology; Quantum superposition; Decoherence; Early universe; Late universe; Environmental noise; Quantum–classical transition; Interaction density; Foundations of physics; Conceptual physics
We discuss several proposals for astrophysical and cosmological tests of quantum theory. The tests are motivated by deterministic hidden-variables theories, and in particular by the view that quantum physics is merely an effective theory of an equilibrium state. The proposed tests involve searching for nonequilibrium violations of quantum theory in: primordial inflaton fluctuations imprinted on the cosmic microwave background, relic cosmological particles, Hawking radiation, photons with entangled partners inside black holes, neutrino oscillations, and particles from very distant sources.