Horizons 2020

Abstract

Horizons of black holes or cosmologies are peculiar loci of spacetime where interesting physical effects takes place, some of which are probed by recent (EHT and LIGO) and future experiments (ET and LISA). We discuss that there are boundary degrees of freedom residing at the horizon. We describe their symmetries and their interactions with gravitational waves. This fits into a larger picture of boundary plus bulk degrees of freedom and their interactions in gauge theories. Existence and dynamics of the near horizon degrees of freedom could be crucial to address fundamental questions and apparent paradoxes in black holes physics.

arXiv comment6 pages, Essay awarded an honorable mention in the Gravity Research Foundation 2020 Awards for Essays on Gravitation

References in corpus (15)

• Black Holes: Complementarity or Firewalls?
• Black holes as mirrors: quantum information in random subsystems
• Information in Black Hole Radiation
• The Stretched Horizon and Black Hole Complementarity
• The fuzzball proposal for black holes: an elementary review
• Soft Hair on Black Holes
• Supertranslations and Superrotations at the Black Hole Horizon
• Generic Isolated Horizons and their Applications
• Extended Symmetries at the Black Hole Horizon
• Spacetime structure near generic horizons and soft hair
• Most general AdS_3 boundary conditions
• T-Witts from the horizon
• Horizon fluff, semi-classical black hole microstates - Log-corrections to BTZ entropy and black hole/particle correspondence
• Residual Diffeomorphisms and Symplectic Softs Hairs: The Need to Refine Strict Statement of Equivalence Principle
• Black hole entropy from non-proper gauge degrees of freedom: II. The charged vacuum capacitor

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• Null boundary phase space: slicings, news and memory
• Symmetries at Null Boundaries: Two and Three Dimensional Gravity Cases
• Anomalies in gravitational charge algebras of null boundaries and black hole entropy
• Conservation and Integrability in Lower-Dimensional Gravity
• Holographic Lorentz and Carroll Frames
• Null Surface Thermodynamics
• Symmetries at Causal Boundaries in 2D and 3D Gravity
• 3d gravity in Bondi-Weyl gauge: charges, corners, and integrability
• Chiral Massive News: Null Boundary Symmetries in Topologically Massive Gravity
• The partial Bondi gauge: Gauge fixings and asymptotic charges
• Celestial $w_{1+\infty }$ charges and the subleading structure of asymptotically-flat spacetimes
• On Symplectic Form for Null Boundary Phase Space
• Can we detect a supertranslated black hole?
• The symmetries of magnetized horizons
• Deformation of Asymptotic Symmetry Algebras and Their Physical Realizations
• Null Surface Thermodynamics in Topologically Massive Gravity
• Linearized gravity and soft graviton theorem in de Sitter spacetime
• Null infinity as a Killing horizon
• Using thermodynamics to learn gravitational wave physics
• Lectures on the Bondi--Metzner--Sachs group and related topics in infrared physics