Black Holes and Information  

In General > s.a. black holes [as computers]; black-hole thermodynamics; gravitational collapse; CPT theorem; quantum black holes.
* Information loss paradox: There is an apparent paradox in the fact that, after a black hole has formed, evaporated (with creation of a mixed state), and disappeared, most the information about what went in it has disappeared with it, since the thermal radiation is in a mixed state and can't carry the information.
* History: Various authors, including Hawking in 2004 with a well-publicized announcement, have suggested that the resolution lies in quantum correlations; 2016, An article by Hawking, Perry and Strominger suggests that the answer might be in the soft hair a black hole can have, and in the related fact that the vacuum state for quantum gravity in a black-hole background is not unique.
* And observation: If one takes into account what is actually seen in the processes of black-hole formation and objects falling into already formed black holes, one reaches the conclusion that (i) Unless there were black holes from the beginning no fully formed ones can be seen, what one sees instead are "frozen stars", and (ii) No matter can be "lost" beyond the horizon.
* And CPT: The evaporation process indicates that there is a preferred arrow of time, along which there is a loss of information in the total process of black-hole formation and evaporation.

Related Topics and Phenomena > s.a. black-hole radiation and properties; time in quantum gravity.
@ And locality: Giddings & Lippert PRD(04)ht; Giddings MPLA(07)-a0705-GRF; Giddings CQG(11)-a0911 [non-locality vs complementarity]; Giddings PRD(12)-a1201.
@ Radiation and unitarity: Page PRL(93)ht, IJMPD(94); Kiefer et al MPLA(94); Yurtsever & Hockney qp/03; Adami & Ver Steeg CQG-gq/04 [with stimulated emission]; Horowitz & Maldacena JHEP(04) [final state boundary conditions]; Casher & Raz a0705 [models of remnants]; Hsu a1302 [and macroscopic superpositions]; Lloyd & Preskill JHEP(14)-a1308 [in final-state projection models]; Jacobson IJMPD(13); Nikolić JCAP(15)-a1502 [and energy-momentum conservation]; > s.a. Unitarity.
@ And measurements / accessible information: Itzhaki CQG(95)ht, PRD(96)ht/95; Vachaspati et al PRD(07)gq/06 + sr(07)jun [quantum formation, no loss of information seen by observers]; Mathur a1104; Zhang et al PRD(13)-a1302 [towards experimental tests]; Ramakrishna & Narayan a1707 [delayed-choice double slit experiment].
@ And correlations: Wald FP(86); Cerf & Adami CSF(99)qp; Peres FdP(04)qp-proc, FP(05); Sen De & Sen PRA(05)qp/04; Arzano MPLA(06)ht/05 [leak through horizon]; Braunstein & Pati PRL(07) [entanglement makes it worse]; Braunstein et al PRL(13)-a0907 + news ns(13)mar [and entanglement entropy]; Zhang et al IJMPD(13); Grudka et al a1506 [and violation of entanglement monogamy]; Strominger a1706 [between hard and soft radiation].
@ And AdS-cft: Lowe & Thorlacius PRD(99); Lunin & Mathur NPB(02); Maia IJMPD(05)gq-GRF; Pando IJMPD(14)-a1405-GRF [and quantum chaos].
@ And decoherence: Kiefer gq/03-proc; Gambini et al IJMPD(04)ht/04 [relational time], PRL(04)ht [realistic clocks]; Hsu & Reeb PRD(09)-a0903 [vs collapse]; Hsu a1003-proc; > s.a. black-hole analogs.
@ Endpoint of evaporation: Rodrigues et al PRL(89); Giddings PRD(92)ht; Russo et al PRD(92); Hawking & Stewart NPB(93) [thunderbolt singularity]; Kim & Lee PLB(99)gq [2D, wormhole]; Fabbri et al NPB(01)ht/00 [near extremal]; Das et al IJMPD(01)gq [asymptotically AdS, naked singularity]; Bambi CMP(09)-a0803 [in de Sitter]; Kiefer et al AdP(09)-a0812 [two-oscillator model]; Maziashvili a0901 [no remnants in RG-modified gravity]; Xiang et al IJMPD(13)-a1305 [argument for remnant]; Rovelli & Vidotto IJMPD(14)-a1401 [Planck stars]; Mathur IJMPD(14)-a1406-GRF [three types]; Calmet CQG(15)-a1412 [and low-energy physics]; Chen et al PRP(15)-a1412 [types of remnants, and the information loss paradox].

References > s.a. black-hole geometry; information theory / quantum field theory in curved spacetime [statistical aspects].
@ Reviews: Giddings ht/92-ln, ht/93, ht/95-proc; Susskind SA(97)apr; Belot et al BJPS(99); Bekenstein CP(04)qp/03; Ginsparg NYT(04)phy; Russo ht/05-conf; Einhorn ht/05-proc; Lloyd pw(06)sep; Mathur LNP(09)-a0803; Susskind 08; Mathur CQG(09)-a0909-ln, a1108, comment Cai et al a1210; Mathur IJMPD(13)-a1308-GRF; Harlow a1409-ln; Okon & Sudarsky a1607 [and the measurement problem]; Polchinski a1609-ln; Chakraborty & Lochan a1702; Unruh & Wald a1703-RPP; Marolf a1703-RPP.
@ General: Lee & Shiekh GRG(91); Bekenstein PRL(93)ht; Danielsson & Schiffer PRD(93)gq; Banks NPPS(95)ht/94; Giddings PRD(94), PRD(94)ht/93; Schiffer PRD(93)ht; Albrecht PRD(94); Page in(94)ht/93; Slater PRD(94); Stephens et al CQG(94)gq/93; 't Hooft gq/95-in; Horowitz & Marolf PRD(97)ht/96 [storage]; Mashkevich gq/97; Balasubramanian et al GRG(06)ht; Zhang et al MPLA(06); Casini PRD(09)-a0712 [distribution of information in evaporation process]; Nikolić a0806 [semiclassical vs quantum treatment]; Liberati et al GRG(10)-a0904; Brustein a1209 [reduction to the microscopic theory of gravity at the highest densities]; Giddings PT(13)apr [and the foundations of physics]; Brustein & Medved JHEP(14)-a1310 [phases of information release]; Modak et al GRG(15)-a1406 [information loss but no paradox]; Brustein & Medved PRD(15)-a1407 [rate of information release].
@ Unitarity, no information loss: Englert ht/97-conf; Mathur IJMPA(00) [string-motivated]; Adami & Ver Steeg CQG-gq/04 [stimulated, non-thermal radiation]; Hayward gq/05-conf, gq/05-in; Smolin & Oppenheim PRL(06)ht/05-conf [how to store the information]; Hawking PRD(05)ht [as scattering problem in AdS]; Zeh PLA(05)gq [consequences]; Lowe & Thorlacius PRD(06)ht; Giddings ht/06, PRD(06)ht; Nikolić EPJC(08)-a0708; Ashtekar et al PRL(08)-a0801 [2D model]; Gielen IJQI(09)-a0905; Mathur IJMPD(09)-a0905-GRF; Zhang et al AP(11)-a0906 [Hawking radiation as tunneling]; Dragan a1003/PRL; Nikolić a1102 [fundamental unitarity, effective information loss]; Hawking a1401 + news ns(14)jan [apparent horizon but no event horizon, information is effectively lost, but without loss of unitarity]; Nikolić IJQI-a1405 [if time is a local observable]; Emelyanov a1507; Chatwin-Davies et al PRL(15)-a1507 [retrieval of a qubit]; Lochan et al PRD(16)-a1604 [information retrieval]; Maudlin a1705 [paradox should be dismissed].
@ And quantum gravity / gup: Adler et al GRG(01)gq [endpoint]]; Shalyt-Margolin MPLA(04); Nozari & Mehdipour EPL(08)-a0804; Terno a0909-proc; Bojowald FrP(15)-a1409 [aggravated information-loss problem in lqg]; Pérez CQG(15)-a1410 [role of discreteness, no firewalls]; Eyheralde et al a1705.
@ And strings / branes: Mathur IJMPD(02)ht-GRF, ht/04-in [branes]; Amati LNP(08)-ht/06; Mathur Pra(12)-a1201-proc.
@ Tunneling proposal: Singleton et al JHEP(10)-a1005 [quantum corrections and back-reaction]; Roy & Rahat a1406 [it does not resolve the paradox].
@ And wave function collapse: Okon & Sudarsky FP(15)-a1406; Modak et al PRD(15)-a1408; Modak & Sudarsky a1607-fs [rev].
@ Other proposed solutions: Castro & Granik phy/00 [and New Relativity]; Herrera IJMPD(09)-a0709 [information erasure]; Hossenfelder & Smolin PRD(10)-a0901 [re conservative solutions]; Nikolić PLB(09)-a0905, IJQI-a0912 [spacetime view]; Israel & Yun PRD(10)-a1009 [deviations from exact thermality]; Pappas IJTMP-a1009, MPLA(12)-a1201; Smolin PRD(14)-a1108 [and relative locality]; Chen a1111 [information-theoretic]; Roy et al a1312 [correlations do not resolve the paradox]; Patrascu JMP(16)-a1410 [and the universal coefficient theorem]; Requardt a1503 [with explicit entanglement of matter and quantum gravity degrees of freedom]; Bedingham et al a1604 [and spontaneous wave-function collapse]; Emelyanov a1703 [negative photon mass squared]; > s.a. models of topology change.
@ Information recovery: Balasubramanian & Czech CQG(11)-a1102 [quantitative approaches]; Lochan & Padmanabhan PRL(16)-a1507 [from the radiation]; Hawking a1509-talk [supertranslations; information recoverable in principle, but lost for all practical purposes]; Mersini-Houghton CQG(16)-a1511 [and entropy].
@ Related topics: Page ht/94 [speculative, and consciousness]; Hod PLA(02)gq/00 [and discreteness]; Nieuwenhuizen & Volovich ht/05 [different entropies]; Srikanth & Hebri QIP(08)-a0705 [and Gödel incompleteness]; Müller et al JHEP(12)-a1206, FP(14) [in generalized probabilistic theories]; Kay a1209 [incompleteness of argument, and remedy]; Nomura et al PRD(13); Gyongyosi IJQI-a1311 [statistical communication model]; Brádler & Adami JHEP(14)-a1310 [transmission of quantum information]; Freivogel JCAP(14)-a1401 [and the firewall]; Ong a1602-proc [and the black-hole interior]; Baccetti et al Ent(17)-a1610 [problems, comments]; > s.a. Fuzzballs.
> Online resources: hear & see Hawking's second Reith lecture.

"Not only does God play with dice, but he sometimes throws them where they can't be seen" – S W Hawking


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