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Through the Bounce: The Frame-Deficit Dictionary Across Loop Quantum Cosmology and the Bounce-Time Cat

Mustafa Boudjerada

Published Aug 25, 2026• 0 citations
Publisher

Abstract

This note extends the frame-deficit dictionary into an exactly solvable loop quantum cosmology structure, studying how information deficits, records, and entropic bounds behave through a quantum cosmological bounce. The model realizes the solvable loop quantum cosmology dynamics of a massless scalar universe on a lattice, where contraction, a positive-volume bounce, and expansion form a single unitary relational evolution. The paper establishes four results. First, the bounce is exactly characterized: every wavepacket universe contracts, reaches a minimum positive volume, and re-expands, with the expected symmetric bounce behavior of the solvable loop quantum cosmology model. Second, information is preserved across the bounce: relational evolution remains unitary, the pre-bounce state is recoverable, and the frame deficit remains invariant before, during, and after the bounce. Third, a quantum superposition of universes with different bounce times is studied. Matter records decohere the question of when the bounce occurred, and the interference between different bounce histories decreases exactly according to the record overlap. Fourth, the deficit–classicality entropic bound remains valid throughout the entire bounce evolution. The result extends the frame-deficit framework from Wheeler–DeWitt quantum cosmology to a nonsingular bouncing universe, showing that the information structure survives the transition replacing the classical singularity. The paper also distinguishes established loop quantum cosmology results from the new contribution: the bounce dynamics and cosmic recall belong to the existing solvable LQC framework, while the new results concern the information dictionary, the invariant deficit structure, and the exact bounce-time decoherence law. The scope is limited to the exactly solvable isotropic lattice realization of loop quantum cosmology. No claim is made for full Einstein dynamics, anisotropic models, or a complete theory of quantum gravity. All results are based on pre-registered predictions, computational verification, and reproducibility materials.

DOI
10.5281/zenodo.22095208

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This note extends the frame-deficit dictionary into an exactly solvable loop quantum cosmology structure, studying how information deficits, records, and entropic bounds behave through a quantum cosmological bounce. The model realizes the solvable loop quantum cosmology dynamics of a massless scalar universe on a lattice, where contraction, a positive-volume bounce, and expansion form a single unitary relational evolution. The paper establishes four results. First, the bounce is exactly characterized: every wavepacket universe contracts, reaches a minimum positive volume, and re-expands, with the expected symmetric bounce behavior of the solvable loop quantum cosmology model. Second, information is preserved across the bounce: relational evolution remains unitary, the pre-bounce state is recoverable, and the frame deficit remains invariant before, during, and after the bounce. Third, a quantum superposition of universes with different bounce times is studied. Matter records decohere the question of when the bounce occurred, and the interference between different bounce histories decreases exactly according to the record overlap. Fourth, the deficit–classicality entropic bound remains valid throughout the entire bounce evolution. The result extends the frame-deficit framework from Wheeler–DeWitt quantum cosmology to a nonsingular bouncing universe, showing that the information structure survives the transition replacing the classical singularity. The paper also distinguishes established loop quantum cosmology results from the new contribution: the bounce dynamics and cosmic recall belong to the existing solvable LQC framework, while the new results concern the information dictionary, the invariant deficit structure, and the exact bounce-time decoherence law. The scope is limited to the exactly solvable isotropic lattice realization of loop quantum cosmology. No claim is made for full Einstein dynamics, anisotropic models, or a complete theory of quantum gravity. All results are based on pre-registered predictions, computational verification, and reproducibility materials.
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A fundamental issue for any quantum cosmological theory is to specify how probabilities can be assigned to various quantum events or sequences of events such as the occurrence of singularities or bounces. In previous work, we have demonstrated how this issue can be successfully addressed within the consistent histories approach to quantum theory for Wheeler-DeWitt-quantized cosmological models. In this work, we generalize that analysis to the exactly solvable loop quantization of a spatially flat, homogeneous and isotropic cosmology sourced with a massless, minimally coupled scalar field known as sLQC. We provide an explicit, rigorous and complete decoherent-histories formulation for this model and compute the probabilities for the occurrence of a quantum bounce versus a singularity. Using the scalar field as an emergent internal time, we show for generic states that the probability for a singularity to occur in this model is zero, and that of a bounce is unity, complementing earlier studies of the expectation values of the volume and matter density in this theory. We also show from the consistent histories point of view that all states in this model, whether quantum or classical, achieve arbitrarily large volume in the limit of infinite 'past' or 'future' scalar 'time', in the sense that the wave function evaluated at any arbitrary fixed value of the volume vanishes in that limit. Finally, we briefly discuss certain misconceptions concerning the utility of the consistent histories approach in these models. © 2013 IOP Publishing Ltd.
This note studies how a universe can generate its own classical records without any external environment or inserted measurement registers. In a solvable anisotropic quantum cosmology model with a Bianchi-I-lite constraint, the two kernel branches correspond to opposite relational arrows of time. The anisotropy degree of freedom evolves differently in the two branches, and this internal motion dynamically writes a record of which relational arrow the universe follows. The paper proves an exact self-decoherence law: the visibility between the two arrow branches is given by the characteristic function of the universe’s own clock-energy distribution. The decoherence rate is determined by the energy variance, and the record–visibility relation satisfies the exact Englert duality. Thus, the same mathematical structure governing information deficits, records, and revival phenomena in the companion framework appears here as a self-generated cosmological decoherence mechanism. The results establish a complete chain: constraint → relational motion → internal records → classicality. Unlike previous exact emergence-of-classicality models in the series, where matter records were introduced as fixed registers, this model generates the records dynamically from the universe’s own degrees of freedom. The universe acts as its own environment. The paper also identifies the boundaries of the result: dispersion returns because of the nonlinear spectrum, and finite-spectrum recurrences appear beyond the declared window. These effects are explicitly analyzed and distinguished from the continuum behavior. The work is limited to a solvable anisotropic minisuperspace model with one anisotropy degree of freedom and a fixed volume-momentum sector. It does not claim a result for full Bianchi cosmology or complete Einstein dynamics. All results are based on pre-registered predictions, computational verification, and reproducibility materials.
A fundamental issue for any quantum cosmological theory is to specify how probabilities can be assigned to various quantum events or sequences of events such as the occurrence of singularities or bounces. In previous work, we have demonstrated how this issue can be successfully addressed within the consistent histories approach to quantum theory for Wheeler–DeWitt-quantized cosmological models. In this work, we generalize that analysis to the exactly solvable loop quantization of a spatially flat, homogeneous and isotropic cosmology sourced with a massless, minimally coupled scalar field known as sLQC. We provide an explicit, rigorous and complete decoherent-histories formulation for this model and compute the probabilities for the occurrence of a quantum bounce versus a singularity. Using the scalar field as an emergent internal time, we show for generic states that the probability for a singularity to occur in this model is zero, and that of a bounce is unity, complementing earlier studies of the expectation values of the volume and matter density in this theory. We also show from the consistent histories point of view that all states in this model, whether quantum or classical, achieve arbitrarily large volume in the limit of infinite 'past' or 'future' scalar 'time', in the sense that the wave function evaluated at any arbitrary fixed value of the volume vanishes in that limit. Finally, we briefly discuss certain misconceptions concerning the utility of the consistent histories approach in these models.
We study the quantum dynamics in Krylov space of a spatially flat, homogeneous, and isotropic universe sourced with a massless scalar field within Wheeler-DeWitt (WDW) quantum cosmology and loop quantum cosmology (LQC) frameworks. The availability of a physical Hilbert space and physical Hamiltonian and the presence of an internal clock enable us to construct the Krylov basis analytically by applying the Lanczos algorithm. We then evaluate both the Krylov state and operator complexity for WDW quantum cosmology and LQC on this basis. In regimes where the wave function of the universe is sharply peaked, our results indicate that the Krylov complexity grows quadratically with the scalar field clock for the state and operator complexities in both the WDW quantum cosmology and LQC. We further show that the operator complexity is exactly twice the state complexity in these regimes. We discuss the interpretation of the global behavior of these systems by calculating the Krylov entropy for both quantum cosmological frameworks. We observe that in LQC, the Krylov complexity and entropy remain finite at the bounce, whereas in the WDW quantum cosmology, they diverge at the big bang/crunch singularity. Our work provides the first example of computing Krylov complexity for a system with a totally constrained Hamiltonian and no external time, a framework to calculate a purely quantum-mechanical entropy in quantum cosmology, and, to our knowledge, the first direct bridge between Krylov complexity and canonical quantum cosmology, as a first step toward understanding how polymerized quantum geometry modifies complexity and entropy.
We review the application of the consistent (or decoherent) histories formulation of quantum theory to canonical loop quantum cosmology. Conventional quantum theory relies crucially on “measurements” to convert unrealized quantum potentialities into physical outcomes that can be assigned probabilities. In the early universe and other physical contexts in which there are no observers or measuring apparatus (or indeed, in any closed quantum system), what criteria determine which alternative outcomes may be realized and what their probabilities are? In the consistent histories formulation it is the vanishing of interference between the branch wave functions describing alternative histories — as determined by the system’s decoherence functional — that determines which alternatives may be assigned probabilities. We describe the consistent histories formulation and how it may be applied to canonical loop quantum cosmology, describing in detail the application to homogeneous and isotropic cosmological models with scalar matter. We show how the theory may be used to make definite physical predictions in the absence of “observers”. As an application, we demonstrate how the theory predicts that loop quantum models “bounce” from large volume to large volume, while conventional “Wheeler–DeWitt”-quantized universes are invariably singular. We also briefly indicate the relation to other work.