2018/11/30 by Xi Dong · 24 citations
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Brane cosmology #Canonical ensemble #Classical mechanics #Cosmology and Gravitation Theories #Entropy (arrow of time) #Grand canonical ensemble #Gravitation #Mathematical physics #Mathematics #Microcanonical ensemble #Noncommutative and Quantum Gravity Theories #Physics #Quantum mechanics #Statistical physics #Statistics #Theoretical physics #cond-mat.stat-mech #gr-qc #hep-th #quant-ph
paper · pdf · doi:10.1103/physrevlett.122.041602
published in Physical Review Letters 122(4), 041602 (American Physical Society) · 6 pages, 2 figures; v2: title slightly changed, new references and minor clarifications added, version to be published in PRL
arxiv created 2019/01/09 · openalex publication_date 2019/02/01 · arxiv updated 2019/02/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We show that Rényi entropies of subregions can be used to distinguish when the entire system is in a microcanonical ensemble from when it is in a canonical ensemble, at least in theories holographically dual to gravity. Simple expressions are provided for these Rényi entropies in a particular thermodynamic limit with high energy density and fixed fractional size of the subregion. Holographically, the Rényi entropies are determined by the areas of cosmic branes inserted into the bulk spacetime. They differ between a microcanonical and a canonical ensemble because the two ensembles provide different boundary conditions for the gravitational theory under which cosmic branes lead to different backreacted geometries. This is in contrast to the von Neumann entropy which is more coarse-grained and does not differentiate microcanonical ensembles from canonical ensembles.