Generalized second law for cosmology

2015/10/07 by Raphael Bousso, Netta Engelhardt · 1 citation
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Conjecture #Cosmology #Cosmology and Gravitation Theories #Entropy (arrow of time) #Event (particle physics) #Event horizon #First law #Galaxies: Formation, Evolution, Phenomena #Mathematical analysis #Mathematical physics #Mathematics #Monotonic function #Physics #Pure mathematics #Quantum #Quantum entanglement #Quantum mechanics #Theoretical physics #gr-qc #hep-th

paper · pdf · doi:10.1103/physrevd.93.024025

published as Phys. Rev. D 93, 024025 (2016) · 14 pages, 5 figures

arxiv created 2015/10/07 · openalex publication_date 2016/01/13 · arxiv updated 2016/01/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We conjecture a novel generalized second law that can be applied in cosmology, regardless of whether an event horizon is present: the generalized entropy increases monotonically outside of certain hypersurfaces we call past Q-screens. A past Q-screen is foliated by surfaces whose generalized entropy (sum of area and entanglement entropy) is stationary along one future null direction and increasing along the other. We prove that our generalized second law holds in spacetimes obeying the quantum focusing conjecture. An analogous law applies to future Q-screens, which appear inside evaporating black holes and in collapsing regions.

Citations

• Holography and Cosmology
• Black Hole Entropy and Induced Gravity
• Average entropy of a subsystem
• Universal upper bound on the entropy-to-energy ratio for bounded systems
• Comparison of the Noether charge and Euclidean methods for computing the entropy of stationary black holes
• Gravitational Collapse and Space-Time Singularities
• Entropy and Area
• Particle creation by black holes
• Holographic Derivation of Entanglement Entropy from AdS/CFT
• Generalized second law of thermodynamics in black-hole physics
• The Holographic Bound in Anti-de Sitter Space
• The World as a Hologram
• Black Holes and Entropy
• A covariant entropy conjecture
• The large N limit of superconformal field theories and supergravity

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