Gravitational Thermodynamics of Causal Diamonds in (A)dS

Understand

The static patch of de Sitter spacetime and the Rindler wedge of Minkowski spacetime are causal diamonds admitting a true Killing field, and they behave as thermodynamic equilibrium states under gravitational perturbations.

• We explore the extension of this gravitational thermodynamics to all causal diamonds in maximally symmetric spacetimes.
• Although such diamonds generally admit only a conformal Killing vector, that seems in all respects to be sufficient.
• We establish a Smarr formula for such diamonds and a "first law" for variations to nearby solutions.