Black Holes |

**In General**
> s.a. history of general relativity; {#einstein}.

* __Early idea__: Calculation by
clergyman John Michell in 1784 for a situation in which the escape speed equals
*c* (however, because of addition of velocities, in Newtonian theory light
emitted by a moving source could escape).

* __History__: The Schwarzschild
solution was found early on, but before the work of Oppenheimer & Snyder
black holes were not thought of as real astrophysical objects; The term *black
hole* was introduced by Wheeler, in a 29 dec 1967 ΣΞ-ΦBK lecture;
2019, First radio image of the core of M87 released.

$ __Definition__: A strongly
asymptotically predictable spacetime *M* contains a black hole if \(M\)
is not in \(J^-({\cal I})\), and \(M \setminus J^-({\cal I})\) is the black hole
region; In non-asymptotically flat spacetimes the notion seems to be physically
less relevant, and many theorems would not hold.

* __Remark__: Classically a black hole
can be thought of as a general relativity soliton, but not quantum mechanically,
due to their radiation and instability.

@ __I / II__: Penrose SA(72)may;
Taylor 73;
Peters AS(74);
Asimov 77;
Calder 77;
in Gribbin 77;
Hawking SA(77)jan;
Greenstein 83;
Luminet 92;
Thorne 94;
Ferguson 96;
Musser SA(03)jul;
Melia 09;
Al-Khalili 11;
news ns(14)feb [debate on information, firewals, and all that];
Begelman & Rees 20;
Samuel CS-a2011.

@ __II__:
Ruffini & Wheeler PT(71)jan;
Droz et al PW(96)jan;
Luminet LNP(03)ap/98;
Blandford & Gehrels PT(99)jun;
Raine & Thomas 14;
Brehm a1901-essay.

@ __Books, reviews__: DeWitt^{2}
ed-73 [especially Hawking, Carter intro];
in Misner et al 73;
Wheeler in(73);
Chandrasekhar CP(74),
reprint CP(09);
Bekenstein GRG(82) [and everyday physics];
Chandrasekhar 83;
Novikov & Frolov 89;
Strominger ht/95-ln;
Townsend gq/97-ln;
Wadia gq/97;
Bekenstein in(00)gq/98-ln;
Frolov & Novikov 98;
Horowitz & Teukolsky RMP(99)gq/98;
Wald ed-98;
Fré et al 00;
Hayward gq/00-MG9;
Chruściel LNP(02)gq;
Booth CJP(05)gq [definitions, boundaries];
Papantonopoulos ed-09;
Visser PoS-a0901;
Joshi a1104-BASI [open issues and challenges];
Frolov & Zelnikov 11;
Bronnikov & Rubin 12;
Hayward 13;
Bolotin et al a1305 [137 problems];
Barack et al CQG(19)-a1806 [and fundamental physics];
Lust & Vleeshouwers a1809-ln [information and thermo];
Chruściel 20 [mathematical].

@ __Astrophysical aspects__: Bekenstein ap/04-ln [primer];
Zhang a1003-ch;
Bambi 17;
> s.a. astrophysics.

@ __Refs__: *Black Holes 70–74* London: Inspec 74;
Stephani gq/03 [Laplace and Schiller];
Gallo & Marolf AJP(09)-a0806;
Curiel nAst(19)-a1808 [definition].

> __Related topics__:
see bose-einstein condensates; Irreducible
Mass; Mass Inflation; Smarr Formula;
Superradiance.

__Geometrical properties__:
see black-hole geometry and topology [including inequalities, interior, membrane paradigm];
censorship; horizons; singularities.

__Other properties__:
see black-hole phenomenology; matter near black holes;
particle statistics; black-hole radiation and
thermodynamics [including phase transitions].

**Types of Black Holes and Alternatives**

* __Kerr black hole hypothesis__: The assumption
that the astrophysical black-hole candidates are the Kerr black holes predicted by general
relativity; > s.a. phenomenology.

* __Alternatives__: Horizonless objects that can
mimick many black hole properties are gravastars, boson stars, wormholes and superspinars (objects
spinning faster that the general-relativistic limit); Fermion balls have been ruled out.

@ __General references__:
Verozub & Kochetov AN(01)-a0810 [stability of supermassive objects];
Chapline ap/05-TX [dark energy stars];
Zaslavskii PLB(06)gq;
Schild et al AJ(06)ap [MECOs as quasar engines];
Lemos & Zaslavskii PRD(07)-a0707 [quasiblack holes];
Cardoso et al PRD(08)-a0709 [instabilities];
Verozub NCB(08)-a0806 [in modified gravity theory];
Visser et al PoS-a0902;
Barceló et al AIP(09)-a0909 [semiclassical collapse];
Mottola APPB(10)-a1008 [condensate stars];
Corda et al JoC(11)-a1111 [without horizons and singularities];
Lemos UZKU-a1112-proc [quasiblack holes];
Barceló et al Univ(16)-a1510 [modified geometries];
Cardoso & Pani a1904-LRR [rev];
> s.a. astronomical objects [boson stars, quark stars];
Gravastars; gravitational collapse.

@ __Black stars__: Barceló et al SA(09)oct;
Vachaspati IJMPD(16)-a1611-GRF [gravitational waves and GRBs].

@ __Arguments against black holes__: Moffat ap/97 [galactic centers];
Robertson ap/98/PASP,
ap/98;
Loinger ap/98;
Logunov et al PPN(06)gq/04;
Gershtein et al gq/06;
Marshall a0707;
Petrovay AIP(08)-a0707 [counterargument to Vachaspati et al];
Pinyol Ribas & López Aylagas a1007 [never-stationary gravitational collapse];
Hess et al IJMPA(10) [dark energy in pseudo-complex extension];
Kiselev et al TMP(10)
["physical inconsistency" of the Schwarzschild and Kerr solutions];
Marshall a1103
[collapse stops before the Schwarzschild radius];
Logunov & Mestvirishvili TMP(12) [from Hilbert's causality principle and the equations of general relativity];
Mersini-Houghton & Pfeiffer a1409
+ news hp(14)sep [Hawking radiation back-reaction];
> s.a. MegaEssays page;
Relativistic Theory of Gravitation [no gravitational collapse].

__Related topics__:
see black-hole analogs and doubles; black-hole types;
quantum black holes; solutions;
uniqueness and hair.

**Other References**
> s.a. Antigravity; particle effects
and models; wormholes.

* __Computational complexity__: 1970s, Jacob Bekenstein
showed that black holes set a theoretical maximum on entropy or information storage for any physical system
governed by quantum mechanics; 2016, A Brown et al conjecture that black holes produce complexity at the
fastest possible rate allowed by physical laws, by identifying computational complexity with the action
and showing that it saturates the Margolus-Levitin bound.

@ __Initial-value problem__: Bishop et al PRD(98)gq/97 [multi-black hole];
Eardley PRD(98)gq/97;
Dain et al PRD(02)gq [spinning, conformally flat];
Brandt et al CQG(03)gq/02 [distorted].

@ __Use as computers__: Lloyd Nat(00)aug;
Ng PRL(01)gq/00,
ht/00-proc [limits];
Hitchcock gq/01 [and universe information];
Lloyd & Ng SA(04)nov;
Dvali & Panchenko FdP(16)-a1601;
Dvali et al FdP(17)-a1605 [universality];
Brown et al PRL(16)
+ Hartman Phy(16) [black holes saturate the speed limit complexity growth];
Susskind a1802 [and computational complexity];
Susskind a1808-ln,
a1810-ln [complexity].

@ __Related topics__: Wald AP(74),
PRD(74) [in a uniform magnetic field];
Loustó & Sánchez PLB(88),
IJMPA(89) [back-reaction];
Davies & Moss CQG(89) [through a black hole];
Mellor & Moss PLB(89) [charged black holes in de Sitter space, and wormholes];
Mitra ap/04 [???];
Rabinowitz in(05)ap/04 [paradoxes];
Lemos in(06)gq/05 [and fundamental physics];
Goldberger & Rothstein GRG(06)ht [tower of gravity theories];
Preti FP(09) [validity of Michell-Lapace argument];
Helfer a1105-conf [problematic issues];
Romero a1409-ch [conceptual].

**Online Resources**
> see Astronomy Today article;
hubblesite.org site;
scienceface.org site;
Simulating eXtreme Spacetimes site;
Hawking's Reith Lecture.

main page
– abbreviations
– journals – comments
– other sites – acknowledgements

send feedback and suggestions to bombelli at olemiss.edu – modified 15 nov 2020