Flow Geometry Microstates: Towards a Microscopic Description of de Sitter Entropy

Abstract: The origin of de Sitter entropy is more enigmatic than that of black holes, presenting a fundamental challenge to quantum gravity. While the Gibbons-Hawking formula suggests a statistical interpretation, a concrete construction of the accessible microstates for a static patch observer is still lacking. In this talk, I present a systematic approach to this problem by constructing microstates in “centaur” geometries —solutions that flow from an asymptotic AdS₂ boundary to a dS₂ static patch in the interior. Employing techniques from wormhole statistics and the gravitational path integral, we recover the expected area law for the entropy. Furthermore, we extend this microstate-counting method to the case of a finite-length Einstein–Rosen bridge. This reveals that the Hilbert space of the flow geometry horizon can be spanned by states with a purely dS bridge, with no AdS portion. Our work thus provides a controlled holographic framework for realizing de Sitter microstates. Time permitting, I will also describe ongoing research into the information content of Hawking pairs in cosmology using the algebraic framework.