More About the Spontaneous Breaking of Time Reversal in de Sitter Space

TL;DR

This paper explores how the spontaneous breaking of time-reversal symmetry in de Sitter space relates to the necessity of observers in its quantum theory, clarifying conceptual foundations.

Contribution

It provides a detailed conceptual analysis of how time-reversal symmetry breaking implies the need for observers in de Sitter space.

Findings

Spontaneous symmetry breaking relates to observer necessity

Clarifies conceptual basis of observer role in de Sitter space

Expands on previous implicit arguments

Abstract

It is widely thought that the quantum theory of de Sitter space requires the existence of a physical observer in the static patch. What exactly is meant by an observer is unclear; it could be anything from a few photons with energy just above the Gibbons-Hawking temperature to a gravitationally bound cluster of galaxies. In a recent note I explained that the need for observers can arise from the spontaneous breaking of time-reversal symmetry. This longer paper expands on the subject, filling in conceptual arguments that were implicit but not explicitly stated in the earlier paper.