# Information entropy and dark energy evolution

## TL;DR

This paper explores the role of information entropy in early and late universe evolution, proposing an entangled state framework that links thermodynamics, quantum entropy, and cosmological structure formation, with results consistent with observations.

## Contribution

It introduces an entangled state ansatz for cosmological thermodynamics, connecting information entropy with dark energy and inflation, providing a novel perspective on universe evolution.

## Key findings

- Dark energy reduces to a cosmological constant with zero entanglement.
- Inflation is effectively described by an associated potential.
- Numerical limits align with current observational data.

## Abstract

The information entropy is here investigated in the context of early and late cosmology under the hypothesis that distinct phases of universe evolution are entangled between them. The approach is based on the \emph{entangled state ansatz}, representing a coarse-grained definition of primordial \emph{dark temperature} associated to an \emph{effective entangled energy density}. The dark temperature definition comes from assuming either Von Neumann or linear entropy as sources of cosmological thermodynamics. We interpret the involved information entropies by means of probabilities of forming structures during cosmic evolution. Following this recipe, we propose that quantum entropy is simply associated to the thermodynamical entropy and we investigate the consequences of our approach using the adiabatic sound speed. As byproducts, we analyze two phases of universe evolution: the late and early stages. To do so, we first recover that dark energy reduces to a pure cosmological constant, as zero-order entanglement contribution, and second that inflation is well-described by means of an effective potential. In both cases, we infer numerical limits which are compatible with current observations.