De Sitter Musings

TL;DR

This paper explores the physics of asymptotically de Sitter spacetimes, reviewing classical and quantum aspects, and proposing ideas for holography, while highlighting differences experienced by static patch observers and metaobservers.

Contribution

It provides a comprehensive review of de Sitter spacetime physics and introduces new proposals for holography in these settings.

Findings

Analysis of initial value problems in de Sitter space

Proposals for holographic descriptions of de Sitter spacetimes

Discussion of semiclassical phenomena like black hole nucleation

Abstract

We discuss some of the issues that arise when considering the physics of asymptotically de Sitter spacetimes, and attempts to address them. Our development begins at the classical level, where several initial value problems are discussed, and ends with several proposals for holography in asymptotically de Sitter spacetimes. Throughout the paper we give a review of some basic notions such as the geometry of the Schwarzschild-de Sitter black hole, the Nariai limit, and quantum field theory in a fixed de Sitter background. We also briefly discuss some semiclassical aspects such as the nucleation of giant black holes and the Hartle-Hawking wavefunctional. We end by giving an overview of some open questions. An emphasis is placed on the differences between a static patch observer confined to live in a thermal cavity and the metaobserver who has access to a finite region of the future boundary.