Algebraic Observational Cosmology

• URL: http://arxiv.org/abs/2406.01669v2
• Date: Fri, 28 Jun 2024 16:59:36 GMT
• Title: Algebraic Observational Cosmology
• Authors: Jonah Kudler-Flam, Samuel Leutheusser, Gautam Satishchandran,
• Abstract summary: We construct an algebra of gravitationally-dressed observables accessible to a comoving observer in FLRW spacetimes. An essential quantized degree of freedom is the zero-mode of the inflaton. Due to the inaccessibility of measurements beyond our cosmological horizon, we demonstrate that all states are mixed with well-defined von Neumann entropy.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: What can be measured by an observer in our universe? We address this question by constructing an algebra of gravitationally-dressed observables accessible to a comoving observer in FLRW spacetimes that are asymptotically de Sitter in the past, describing an inflationary epoch. An essential quantized degree of freedom is the zero-mode of the inflaton, which leads to fluctuations in the effective cosmological constant during inflation and prevents the existence of a maximum entropy state in the semiclassical limit. Due to the inaccessibility of measurements beyond our cosmological horizon, we demonstrate that all states are mixed with well-defined von Neumann entropy (up to a state-independent constant). For semiclassical states, the von Neumann entropy corresponds to the generalized entropy of the observer's causal diamond, a fine-grained quantity that is sensitive to the initial conditions of the universe.

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