Soft Hair on Black Holes.
By S. Hawking, M. Perry, Andrew Strominger. Physical Review Letters, 2016
760 citations recorded by the source corpus.
It has recently been shown that Bondi-van der Burg-Metzner-Sachs supertranslation symmetries imply an infinite number of conservation laws for all gravitational theories in asymptotically Minkowskian spacetimes. These laws require black holes to carry a large amount of soft (i.e., zero-energy) supertranslation hair. The presence of a Maxwell field similarly implies soft electric hair. This Letter gives an explicit description of soft hair in terms of soft gravitons or photons on the black hole horizon, and shows that complete information about their quantum state is stored on a holographic plate at the future boundary of the horizon. Charge conservation is used to give an infinite number of exact relations between the evaporation products of black holes which have different soft hair but are otherwise identical. It is further argued that soft hair which is spatially localized to much less than a Planck length cannot be excited in a physically realizable process, giving an effective number of soft degrees of freedom proportional to the horizon area in Planck units.
Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/680078951d9669e2c6ab284d2b5b48c00d56d5ac
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Citations in the corpus
- 4D scattering amplitudes and asymptotic symmetries from 2D CFT (2016, background): “This in some sense offers a sharper form of “hair” [67] compared to the usual asymptotic electric field of a black hole, which remembers the charge that has fallen into the horizon but without regard to the angle of entry.”
- The Holographic Nature of Null Infinity (2020, background): “It would be interesting to understand how much of the information is present in the soft-part of the wavefunction—an issue that was also discussed in [51].”
- Extended symmetries at the black hole horizon (2016, background): “This is mainly motivated by the proposal in [1, 2].”
- Transcending the ensemble: baby universes, spacetime wormholes, and the order and disorder of black hole information (2020, background): “The plethora of proposals for new physics that might be associated with obtaining this Page curve (including [3, 7–39]) were thus all properly viewed as speculative and contained at least some optimistic extrapolation or ad hoc ingredient.”
- Conserved charges of the extended Bondi-Metzner-Sachs algebra (2015, background): “Super center-of-mass (also called soft hair in the context of black holes [46]) Electric parity piece of superrotations (extended BMS algebra) Electric parity piece of angular momentum aspect NA(θ ) Center-of-mass conservation at every angle [Sec.”
- The Ryu–Takayanagi Formula from Quantum Error Correction (2016, background): “In this context these modes (and their gravitational counterparts) have recently been called “soft hair”, by analogy with the asymptotic charges defined at spatial (or null) infinity [44].”
- Scattering of spinning black holes from exponentiated soft factors (2018, background): “An obvious question which arises from this construction is whether it is possible to establish a link between BMS symmetries studied at null/spatial infinity [14, 15, 17–20] (or at the black hole horizon [63, 64]) and classical observables arising from massive amplitudes.”
- Flat holography: aspects of the dual field theory (2016, background): “The authors of [15] argue however that since supertranslations are diffeomorphisms that change the physical state, they map the stationary black hole to a physically inequivalent one and hence all black holes carry an infinity of supertranslation charges.”
- Lectures on the Infrared Structure of Gravity and Gauge Theory (2017, background): “This story is, however, significantly modified [41, 48, 160] by the infinite number of conserved charges discussed in these lectures.”
- Edge modes of gravity. Part I. Corner potentials and charges (2020, background): “Throughout the years, a very substantial amount of work has been dedicated to the study of these corner charges, their algebra, and their possible physical applications [19–30].”
- Superrotation charge and supertranslation hair on black holes (2016, background): “J H E P 0 5 ( 2 0 1 7 ) 1 6 1 infinite number of charges or, equivalently, have an infinite head of ‘soft hair’ [22].”