Document Type : Regular article

Author

• Leonard Susskind

Stanford Institute for Theoretical Physics and Department of Physics

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 one way the need for observers can arise is 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.

Keywords

• Quantum theory
• de Sitter space
• Holography

Main Subjects

• Physics