This paper presents my finding that quantum decoherence during the universe's expansion selected certain states over others. I apply Zurek's well-known einselection concept to cosmology and show that modes near the horizon scale survived, while others decohered into entropy. The main result is that 20-50% of primordial quantum states persisted as classical matter. I derive this from the interaction Hamiltonian without any free parameters. The prediction is testable by Euclid and Planck data within 10 years.
This paper presents my finding that quantum decoherence during the universe's expansion selected certain states over others. I apply Zurek's well-known einselection concept to cosmology and show that modes near the horizon scale survived, while others decohered into entropy. The main result is that 20-50% of primordial quantum states persisted as classical matter. I derive this from the interaction Hamiltonian without any free parameters. The prediction is testable by Euclid and Planck data within 10 years.
We propose that environment-induced decoherence during cosmic expansion was selective rather than uniform. Applying Zurek's einselection framework to cosmology, we argue that expansion-compatible quantum states (pointer states) survived to become classical matter and structure, while expansion-incompatible states (non-pointer states) rapidly diluted into background entropy. Using quantum field theory in FLRW spacetime, we derive the selectivity parameter β ≈ 2-5 and Gaussian horizon-compatibility function f(x_k) = exp[-(ln x_k)²/(2σ²)] from first principles via pointer state condition (minimization of interaction Hamiltonian) combined with adiabaticity analysis in expanding spacetime. The horizon scale x_k = k/(aH) = 1 emerges naturally from variational principle, not as an assumption. Numerical integration yields survival fraction f_survival ≈ 20-50%, explaining why this fraction of primordial quantum states persists as classical degrees of freedom. The framework contains no free parameters beyond standard FLRW cosmology. Predictions: (1) decoherence timescale τ_d ≈ β × τ_H (fundamentally derived); (2) scale-dependent modifications to matter power spectrum P(k) ∝ f(k/aH); (3) observable signatures in CMB power spectrum anomalies and large-scale structure formation patterns testable by Planck, Euclid, and DESI within 5-10 years.
Description : This work introduces a novel, model-independent diagnostic framework for quantifying quantum decoherence in primordial inflationary perturbations. The study addresses the fundamental problem of the quantum-to-classical transition in cosmology by defining a normalized persistence functional that captures the suppression of quantum coherence over time. Within an open quantum system approach, each perturbation mode is treated as an effective quantum degree of freedom interacting with an environment, leading to Gaussian suppression of off-diagonal density matrix elements. The proposed functional provides a direct and scalable measure of decoherence efficiency without relying on detailed microscopic modeling. A key feature of the framework is the introduction of a residual coherence parameter, which accounts for possible late-time deviations from complete classicalization. The work further establishes a monotonicity property for the decoherence functional and connects the persistence measure to entropy growth, offering an information-theoretic interpretation of the decoherence process. Importantly, the framework suggests a phenomenological link between residual coherence and observable non-Gaussianity in the cosmic microwave background, opening a pathway for potential observational constraints. The proposed diagnostic functional is broadly applicable across inflationary models and provides a unified tool for comparing decoherence efficiency under different environmental interactions. This work lays the foundation for future studies on quantum signatures in cosmological observables and the persistence of quantum features in the early universe. Keywords : Quantum Decoherence Inflationary Cosmology Primordial Perturbations Open Quantum Systems Quantum-to-Classical Transition Non-Gaussianity Cosmological Perturbation Theory Density Matrix Quantum Cosmology Early Universe Physics Decoherence Functional Entropy and Information Theory
Inflation stretches quantum vacuum fluctuations into the density ripples we later see imprinted on the cosmic microwave background, yet the initial state is a pure, highly squeezed quantum state. The usual explanation for why those ripples look classical appeals to decoherence and the fading of a "decaying mode." This paper argues that the sharper statement is objectivity: the ripples become a fact for all observers, in the precise sense of quantum Darwinism, exactly when the growing perturbation is redundantly recorded across a vast environment of short-wavelength and gravitational-wave modes. The paper models a single super-horizon mode and its environment exactly. It proves that, once the mode crosses the horizon, its amplitude is recorded so redundantly that even a tiny fragment of the environment already fixes it, while the number of independent records grows without bound as the universe expands. Horizon crossing is therefore a Darwinism–encoding transition: an information measure rises from zero to one bit as the mode freezes. And the environment singles out one objective observable — the curvature amplitude — while its conjugate is only globally encoded, readable by no bounded fragment. The results are closed-form, and their exact algebraic cores are verified by proof-checking software. The record strength is not a free parameter: it is fixed by the mode's decoherence, computed from gravitational theory, and the leftover quantum coherence falls off exponentially with the redundancy. In short: the sky is classical not merely because it decohered, but because horizon crossing broadcast it — copying each primordial fluctuation until it became a fact for everyone.
Description: This work presents a quantitative framework for describing the quantum–classical transition as a continuous dynamical process governed by open quantum system interactions. A normalized Quantum Persistence Function is introduced to measure residual quantum coherence, allowing classical emergence to be characterized through a scale-dependent suppression criterion. The model is constructed using a microscopic spin–boson open-system foundation and extends decoherence analysis to inflationary cosmology. The framework connects dynamical decoherence bounds with observational constraints derived from primordial statistics measured by the Planck Collaboration. The formulation builds conceptually on decoherence theory associated with Wojciech H. Zurek and provides a diagnostic criterion for residual coherence survival across cosmological scales. The results aim to provide a practical quantitative tool for evaluating classicalization efficiency in inflationary models and for relating open-system quantum dynamics to empirical cosmological observations. KEYWORDS: Quantum–classical transition; decoherence theory; open quantum systems; inflationary cosmology; residual quantum coherence; spin–boson model; classicalization dynamics; primordial perturbations; cosmological quantum mechanics
Our observed Universe has a very strong arrow of time rooted in its low entropy starting point. This low entropy start can be related to various ``tuning puzzles'' about the early state of the Universe. Here we explore the relationship between the arrow of time and the emergence of classical from quantum in the hopes of ultimately gaining insights into cosmological initial conditions. Our focus is on einselection, the process whereby interactions with an environment select preferred states for a quantum system. This process plays an essential role in the emergence of classical from quantum. Studies of einselection have so far been limited to cases that exhibit an arrow of time. Here we study the ability of equilibrium systems to exhibit einselection---and investigate whether detailed balance prevents this---motivated by the question of whether classicality requires an arrow of time. We present calculations in the adapted Caldeira-Leggett model which demonstrate that einselection can indeed take place in equilibrium systems, and show how this phenomenon is tied to histories which express an arrow of time, despite the global equilibrium. We discuss some interesting implications of our results for cosmology and cosmological initial conditions. We are intrigued and a bit surprised by the role the consistent histories formalism has ended up playing in our analysis.
Substrate framework's energy-eigenstate decoherence formula γeff = (ΔE/MPc2)2 × νP [1] depends on the energy gap between superposed states, not on cosmological distance directly. But typical ΔE values for thermal modes, particle physics processes, and inflaton field fluctuations are functions of cosmic energy density, which evolves dramatically over cosmic history. This paper develops the cosmological evolution of substrate intrinsic decoherence across the principal epochs: • Planck era (t ~ 10−44 s): Substrate framework breaks down; γ formula not applicable. • Inflation era (ΔE ~ 1016 GeV): γ ~ 1037 Hz. Catastrophically fast decoherence drives primordial perturbation classicalization — providing the microscopic mechanism for the well-known but mechanistically unexplained quantum-to-classical transition of cosmological perturbations. • EW epoch (ΔE ~ 100 GeV): γ ~ 109 Hz. Coherence time τ ~ ns; particle physics processes decohere rapidly. • QCD epoch (ΔE ~ 100 MeV): γ ~ 103 Hz. τ ~ ms. • Nucleosynthesis (ΔE ~ MeV): γ ~ 0.1 Hz. τ ~ 10 s. • Recombination (ΔE ~ 0.3 eV): γ ~ 10−15 Hz. τ ~ 30 Myr, longer than the age of the universe at that time — the threshold at which the universe becomes capable of sustaining cosmologically long quantum coherence. • Present era (ΔE ~ kBTCMB ~ 0.2 meV): γ ~ 10−21 Hz. τ ~ 30 Gyr, longer than the current age of the universe. Coherent quantum systems can persist for cosmological timescales. • de Sitter future: Floor of γ set by dark energy; in the limit, decoherence approaches a constant minimum tied to the cosmological constant. Three principal results: (i) The decoherence rate has dropped by ~58 orders of magnitude over cosmic history, from γ ~ 1037 Hz at inflation to γ ~ 10−21 Hz today. The universe has become exponentially more capable of sustaining coherent quantum behavior as it has cooled. (ii) Coherent quantum behavior is a late-universe phenomenon. Modern quantum-mechanical experiments (atom interferometry, molecular interferometry, atomic clocks, B-meson oscillations) require a low-energy-density universe to operate. They could not have been performed in the radiation-dominated era because thermal energies were too high. (iii) Substrate framework provides a microscopic mechanism for primordial perturbation classicalization. Inflaton field quantum fluctuations decohered at γ ~ 1037 Hz during inflation, becoming classical perturbations that seeded the large-scale structure observed today. This resolves a long-standing puzzle in cosmology, where the quantum-to-classical transition is traditionally treated as a black box. Additionally, the cosmological floor on momentum uncertainty Δpmin ≥ ℏH(t)/c evolved from Δpmin ~ MPc at Planck era to Δpmin ~ 10−61 kg·m/s today — a quantum bound that has weakened by ~60 orders of magnitude. In the early universe, quantum uncertainty operated at vastly different scales than today. These results imply that the substrate framework's intrinsic decoherence sector is fundamentally a cosmological history sector: the framework's quantum-mechanical behavior changes character with cosmic epoch. Quantum coherence is not a universal property but rather a feature of low-energy-density universes. The framework's testable predictions in the modern era (thermal molecular interferometry, atomic clocks) are made possible by the universe having sufficiently cooled. Section II clarifies what does and doesn't depend on cosmic time. Section III develops the cosmological floor evolution. Section IV develops the decoherence rate across cosmic history with a master table. Section V addresses the early universe's rapid classicalization. Section VI addresses the inflation era specifically and primordial perturbations. Section VII addresses the present era. Section VIII addresses the de Sitter future. Section IX synthesizes the cross-epoch comparison of quantum properties. Section X concludes. Keywords: substrate theory; cosmological decoherence; primordial perturbations; inflation; quantum-to-classical transition; cosmological floor; energy-eigenstate formula; cosmic evolution of quantum capacity.