Cite as: doi:10.26081/K64T3H

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It was recently shown that the von Neumann algebras of observables dressed to the mass of a Schwarzschild-AdS black hole or an
observer in de Sitter are Type II, and thus admit well-defined traces. The von Neumann entropies of "semi-classical" states were found to be
generalized entropies. However, these arguments relied on the existence of an equilibrium (KMS) state and thus do not apply to, for example,
black holes in asymptotically flat spacetimes or asymptotically de Sitter spacetime. In this talk, I will show that the algebra of
observables in the “exterior” of any black hole horizon always contains a Type II factor "localized" on the horizon and the entropy of
semi-classical states is the generalized entropy.
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