## Abstract

We describe an algebra of observables for a static patch in de Sitter space, with operators gravitationally dressed to the worldline of an observer. The algebra is a von Neumann algebra of Type II_{1}. There is a natural notion of entropy for a state of such an algebra. There is a maximum entropy state, which corresponds to empty de Sitter space, and the entropy of any semiclassical state of the Type II_{1} algebras agrees, up to an additive constant independent of the state, with the expected generalized entropy S_{gen} = (A/4G_{N}) + S_{out}. An arbitrary additive constant is present because of the renormalization that is involved in defining entropy for a Type II_{1} algebra.

Original language | English (US) |
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Article number | 82 |

Journal | Journal of High Energy Physics |

Volume | 2023 |

Issue number | 2 |

DOIs | |

State | Published - Feb 2023 |

## All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics

## Keywords

- Cosmological models
- de Sitter space