Gravitational thermodynamics of causal diamonds


Jacobson, T. (2019). Gravitational thermodynamics of causal diamonds. Perimeter Institute. https://pirsa.org/19050036


Jacobson, Ted. Gravitational thermodynamics of causal diamonds. Perimeter Institute, May. 21, 2019, https://pirsa.org/19050036


          @misc{ pirsa_19050036,
            doi = {},
            url = {https://pirsa.org/19050036},
            author = {Jacobson, Ted},
            keywords = {Quantum Fields and Strings},
            language = {en},
            title = {Gravitational thermodynamics of causal diamonds},
            publisher = {Perimeter Institute},
            year = {2019},
            month = {may},
            note = {PIRSA:19050036 see, \url{https://pirsa.org}}


Black hole (more generally, horizon) thermodynamics is a window into quantum gravity. Can horizon thermodynamics---and ultimately quantum gravity---be quasi-localized? A special case is the static patch of de Sitter spacetime, known since the work of Gibbons and Hawking to admit a thermodynamic equilibrium interpretation. It turns out this interpretation requires that a negative temperature is assigned to the state. I'll discuss this example, and its generalization to all causal diamonds in maximally symmetric spacetimes. This story includes a Smarr formula and first law of causal diamonds, analogous to those of black hole mechanics. I’ll connect this first law to the statement that generalized entropy in a small diamond is maximized in the vacuum at fixed volume.