Beyond the Horizon

TL;DR

This paper investigates how quantum correlations across cosmic horizons in de Sitter space can influence local observations, revealing potential ways to infer properties of regions beyond the horizon.

Contribution

It demonstrates how a particle behind the horizon alters local density matrices, energy, and entropy, suggesting a generic method to infer features beyond horizons.

Findings

A particle behind the horizon changes local energy and entropy.

Quantum correlations can influence local observables across horizons.

The results suggest possible inference of spacetime features beyond horizons.

Abstract

Cosmic horizons arise in general relativity in the context of black holes and in certain cosmologies. Classically, regions beyond a horizon are inaccessible to causal observers. However, quantum mechanical correlations may exist across horizons that may influence local observations. For the case of de Sitter space, we show how a single particle excitation behind the horizon changes the density matrix governing local observables. As compared to the vacuum state, we calculate the change in the average energy and entropy per unit volume. This illustrates what may be a generic property allowing some features of spacetime beyond a horizon to be inferred.