Adventures in de Sitter space

TL;DR

This paper reviews the semi-classical properties of de Sitter space, discusses recent quantum insights, and explores the complexities and entropy bounds relevant to developing a full quantum theory of this spacetime.

Contribution

It provides an overview of quantum aspects of de Sitter space, including black hole instabilities and entropy bounds, advancing understanding beyond earlier semi-classical results.

Findings

Large de Sitter black holes show instabilities.

Entropy bounds specific to de Sitter space are discussed.

Challenges in formulating a complete quantum theory are outlined.

Abstract

This is my contribution to the Festschrift honoring Stephen Hawking on his 60th birthday. Twenty-five years ago, Gibbons and Hawking laid out the semi-classical properties of de Sitter space. After a summary of their main results, I discuss some further quantum aspects that have since been understood. The largest de Sitter black hole displays an intriguing pattern of instabilities, which can render the boundary structure arbitrarily complicated. I review entropy bounds specific to de Sitter space and outline a few of the strategies and problems in the search for a full quantum theory of the spacetime.