skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Unitarity from a smooth horizon?

Abstract

Under semiclassical evolution, black holes retain a smooth horizon but fail to return information. Yet, the Ryu-Takayanagi (RT) prescription computes the boundary entropy expected from unitary conformal field theory (CFT) evolution. We demonstrate this in a novel setting with an asymptotic bulk detector, eliminating an assumption about the entanglement wedge of auxiliary systems. We consider three interpretations of this result. (i) At face value, information is lost in the bulk but not in the CFT. This conflicts with the AdS/CFT dictionary. (ii) No unique quantum field theory state (pure or mixed) governs all detector responses to the bulk Hawking radiation. This conflicts with the existence of an S matrix. (iii) Nonlocal couplings to the black hole interior cause asymptotic detectors to respond as though the radiation was pure, even though it is naively thermal. This invalidates the standard interpretation of the semiclassical state, including its smoothness at the horizon. We conclude that unitary boundary evolution requires asymptotic bulk detectors to become unambiguously pure at late times. We ask whether the RT prescription can still reproduce the boundary entropy in this bulk scenario. We find that this requires a substantial failure of semiclassical gravity in a low-curvature region, such as amore » firewall that purifies the Hawking radiation. Finally, we allow that the dual to semiclassical gravity may be an ensemble of unitary theories. This appears to relax the tensions we find: the ensemble average of out states would be mixed, but the ensemble average of final entropies would vanish.« less

Authors:
;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP); National Science Foundation (NSF); European Research Council (ERC)
OSTI Identifier:
1714414
Alternate Identifier(s):
OSTI ID: 1763683
Grant/Contract Number:  
SC0019380; AC02-05CH11231; PHY1820912; GravBHs-692951
Resource Type:
Published Article
Journal Name:
Physical Review D
Additional Journal Information:
Journal Name: Physical Review D Journal Volume: 102 Journal Issue: 10; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Quantum aspects of black holes; quantum gravity

Citation Formats

Bousso, Raphael, and Tomašević, Marija. Unitarity from a smooth horizon?. United States: N. p., 2020. Web. https://doi.org/10.1103/PhysRevD.102.106019.
Bousso, Raphael, & Tomašević, Marija. Unitarity from a smooth horizon?. United States. https://doi.org/10.1103/PhysRevD.102.106019
Bousso, Raphael, and Tomašević, Marija. Mon . "Unitarity from a smooth horizon?". United States. https://doi.org/10.1103/PhysRevD.102.106019.
@article{osti_1714414,
title = {Unitarity from a smooth horizon?},
author = {Bousso, Raphael and Tomašević, Marija},
abstractNote = {Under semiclassical evolution, black holes retain a smooth horizon but fail to return information. Yet, the Ryu-Takayanagi (RT) prescription computes the boundary entropy expected from unitary conformal field theory (CFT) evolution. We demonstrate this in a novel setting with an asymptotic bulk detector, eliminating an assumption about the entanglement wedge of auxiliary systems. We consider three interpretations of this result. (i) At face value, information is lost in the bulk but not in the CFT. This conflicts with the AdS/CFT dictionary. (ii) No unique quantum field theory state (pure or mixed) governs all detector responses to the bulk Hawking radiation. This conflicts with the existence of an S matrix. (iii) Nonlocal couplings to the black hole interior cause asymptotic detectors to respond as though the radiation was pure, even though it is naively thermal. This invalidates the standard interpretation of the semiclassical state, including its smoothness at the horizon. We conclude that unitary boundary evolution requires asymptotic bulk detectors to become unambiguously pure at late times. We ask whether the RT prescription can still reproduce the boundary entropy in this bulk scenario. We find that this requires a substantial failure of semiclassical gravity in a low-curvature region, such as a firewall that purifies the Hawking radiation. Finally, we allow that the dual to semiclassical gravity may be an ensemble of unitary theories. This appears to relax the tensions we find: the ensemble average of out states would be mixed, but the ensemble average of final entropies would vanish.},
doi = {10.1103/PhysRevD.102.106019},
journal = {Physical Review D},
number = 10,
volume = 102,
place = {United States},
year = {2020},
month = {11}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
https://doi.org/10.1103/PhysRevD.102.106019

Save / Share:

Works referenced in this record:

The Page curve of Hawking radiation from semiclassical geometry
journal, March 2020

  • Almheiri, Ahmed; Mahajan, Raghu; Maldacena, Juan
  • Journal of High Energy Physics, Vol. 2020, Issue 3
  • DOI: 10.1007/JHEP03(2020)149

Quantum extremal surfaces: holographic entanglement entropy beyond the classical regime
journal, January 2015


Violations of the Equivalence Principle by a Nonlocally Reconstructed Vacuum at the Black Hole Horizon
journal, January 2014


Holographic representation of local bulk operators
journal, September 2006


Entanglement wedge reconstruction and the information paradox
journal, September 2020


Gauge-Gravity Duality and the Black Hole Interior
journal, October 2013


Black holes and the second law
journal, August 1972

  • Bekenstein, J. D.
  • Lettere Al Nuovo Cimento Series 2, Vol. 4, Issue 15
  • DOI: 10.1007/BF02757029

The stretched horizon and black hole complementarity
journal, October 1993


Black hole explosions?
journal, March 1974


An apologia for firewalls
journal, September 2013

  • Almheiri, Ahmed; Marolf, Donald; Polchinski, Joseph
  • Journal of High Energy Physics, Vol. 2013, Issue 9
  • DOI: 10.1007/JHEP09(2013)018

Black holes: complementarity or firewalls?
journal, February 2013

  • Almheiri, Ahmed; Marolf, Donald; Polchinski, Joseph
  • Journal of High Energy Physics, Vol. 2013, Issue 2
  • DOI: 10.1007/JHEP02(2013)062

Aspects of the Papadodimas-Raju proposal for the black hole interior
journal, November 2014


Cool horizons for entangled black holes
journal, August 2013


Black holes and thermodynamics
journal, January 1976


State-dependent bulk-boundary maps and black hole complementarity
journal, April 2014


Firewalls from double purity
journal, October 2013


Large breakdowns of entanglement wedge reconstruction
journal, December 2019


Constructing local bulk observables in interacting AdS/CFT
journal, May 2011


An infalling observer in AdS/CFT
journal, October 2013

  • Papadodimas, Kyriakos; Raju, Suvrat
  • Journal of High Energy Physics, Vol. 2013, Issue 10
  • DOI: 10.1007/JHEP10(2013)212

Simple holographic models of black hole evaporation
journal, August 2020

  • Akers, Chris; Engelhardt, Netta; Harlow, Daniel
  • Journal of High Energy Physics, Vol. 2020, Issue 8
  • DOI: 10.1007/JHEP08(2020)032

Holographic Derivation of Entanglement Entropy from the anti–de Sitter Space/Conformal Field Theory Correspondence
journal, May 2006


Violations of the Born rule in cool state-dependent horizons
journal, January 2016

  • Marolf, Donald; Polchinski, Joseph
  • Journal of High Energy Physics, Vol. 2016, Issue 1
  • DOI: 10.1007/JHEP01(2016)008

The large $N$ limit of superconformal field theories and supergravity
journal, January 1998


The entropy of bulk quantum fields and the entanglement wedge of an evaporating black hole
journal, December 2019

  • Almheiri, Ahmed; Engelhardt, Netta; Marolf, Donald
  • Journal of High Energy Physics, Vol. 2019, Issue 12
  • DOI: 10.1007/JHEP12(2019)063

Holographic Dual of a Boundary Conformal Field Theory
journal, August 2011


Local bulk operators in AdS/CFT correspondence: A boundary view of horizons and locality
journal, April 2006


Saturating the holographic entropy bound
journal, October 2010


Information flow in black hole evaporation
journal, March 2020

  • Chen, Hong Zhe; Fisher, Zachary; Hernandez, Juan
  • Journal of High Energy Physics, Vol. 2020, Issue 3
  • DOI: 10.1007/JHEP03(2020)152

Information loss
journal, July 2017


Gedanken experiments involving black holes
journal, January 1994


Information radiation in BCFT models of black holes
journal, May 2020

  • Rozali, Moshe; Sully, James; Van Raamsdonk, Mark
  • Journal of High Energy Physics, Vol. 2020, Issue 5
  • DOI: 10.1007/JHEP05(2020)004

A covariant holographic entanglement entropy proposal
journal, July 2007

  • Hubeny, Veronika E.; Rangamani, Mukund; Takayanagi, Tadashi
  • Journal of High Energy Physics, Vol. 2007, Issue 07
  • DOI: 10.1088/1126-6708/2007/07/062

Complementarity is not enough
journal, June 2013


Jerusalem lectures on black holes and quantum information
journal, February 2016


Quantum corrections to holographic entanglement entropy
journal, November 2013

  • Faulkner, Thomas; Lewkowycz, Aitor; Maldacena, Juan
  • Journal of High Energy Physics, Vol. 2013, Issue 11
  • DOI: 10.1007/JHEP11(2013)074