Deconstructing de Sitter

TL;DR

<3-5 sentence high-level summary> Balasubramanian, Hořava, and Minic address the challenge of interpreting de Sitter entropy within string theory. They propose a framework where Euclidean de Sitter space appears as the S^D factor in EdS×AdS compactifications with D-form flux, and where EdS physics is encoded by AdS-localized modes. Using AdS/CFT, they demonstrate that the de Sitter entropy matches the number of degrees of freedom in a dual quantum mechanical description across several compactifications, with explicit scaling I.e. S ∼ N^2, N^{3/2}, N^3, and N corresponding to EdS5×AdS5, EdS7×AdS4, EdS4×AdS7, and EdS3×AdS3, respectively. This provides a holographic, regulator-based perspective on de Sitter space in string theory and links horizon entropy to finite-dimensional Hilbert spaces in the dual QM.

Abstract

Semiclassical gravity predicts that de Sitter space has a finite entropy. We suggest a picture for Euclidean de Sitter space in string theory, and use the AdS/CFT correspondence to argue that de Sitter entropy can be understood as the number of degrees of freedom in a quantum mechanical dual.