2010/07/31 by T. Padmanabhan, Τ. Padmanabhan · 1 citation
Physics and Astronomy · #Black Holes and Theoretical Physics #Classical mechanics #Cosmology and Gravitation Theories #Entropy (arrow of time) #Gravitation #Horizon #Loop quantum gravity #Mathematical physics #Physics #Quantum #Quantum Electrodynamics and Casimir Effect #Quantum entanglement #Quantum gravity #Quantum mechanics #Regularization (linguistics) #Spacetime #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.82.124025
published as Phys.Rev.D82:124025,2010 · ver 2: minor clarifications added; reformatted with Sections; 11 pages
arxiv created 2010/08/27 · openalex publication_date 2010/12/13 · arxiv updated 2010/12/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The calculation of entanglement entropy S of quantum fields in spacetimes with horizon shows that, quite generically, S is (a) proportional to the area A of the horizon and (b) divergent. I argue that this divergence, which arises even in the case of Rindler horizon in flat spacetime, is yet another indication of a deep connection between horizon thermodynamics and gravitational dynamics. In an emergent perspective of gravity, which accommodates this connection, the fluctuations around the equipartition value in the area elements will lead to a minimal quantum of area O(1)LP2, which will act as a regulator for this divergence. In a particular prescription for incorporating the LP2 as zero-point-area of spacetime, this does happen and the divergence in entanglement entropy is regularized, leading to S\ensuremath∝A/LP2 in Einstein gravity. In more general models of gravity, the surface density of microscopic degrees of freedom is different which leads to a modified regularization procedure and the possibility that the entanglement entropy---when appropriately regularized---matches the Wald entropy.