|  Wormholes | 
In General > s.a. causality
  violations ["time machines"]; spacetime
  topology; wormhole solutions.
  * Idea:
    Einstein-Rosen "bridges" or "handles," connecting either (i) different
    universes or regions of one universe (relativists' view), or (ii) two
    timelike related regions of a universe, representing the transient
    phenomenon of emission and reabsorption of a baby universe (hep
    theorists); Usually studied in the Euclidean regime.
  * Motivation:
    Important because they represent non-perturbative features of quantum
    gravity; Interesting for two reasons,
  - Macroscopic: Time travel (need exotic
    matter –enormous negative pressures– but could be made stable);
  - Microscopic: They fix the constants
    of nature (Hawking – Consequences are unpredictable changes in the
    constants, loss of information down the holes; Coleman – Consequence
    is the big fix of the constants, in particular the cosmological constant;
    Unruh – All wrong, one must include more paths in the calculations).
  * Remark: Wormholes appeared
    in an episode of "Star Trek: the Next Generation", 03.1990.
  @ I: issue disc(89)jun; Halpern 92;
    in Thorne 94; Al-Khalili 11;
    news guard(13)jun [Kip Thorne and upcoming film];
    news pbs(13)dec [microscopic channels between particles?].
  @ II:
    Redmount NS(90)apr28;
    Clarke Nat(90);
    Simon PW(94)dec;
    Visser 95;
    James et al AJP(15)jun [visualizing].
  @ III: Bronnikov & Rubin 12.
Phenomenology > s.a. gravitational lensing;
  neutron stars; particle models.
  * Possible observation:
    Bursts associated with their instability, or microlensing with unusual signature.
  @ General references: Frolov & Novikov PRD(93) [as probes of black-hole interiors];
    Kardashev et al IJMPD(07)ap/06;
    Damour & Solodukhin PRD(07)-a0704 [mimicking black holes]; Dzhunushaliev et al 
    JCAP(11)-a1102 [inside a star];
    news sn(11)mar [Folomeev's proposal of phantom-matter-supported stellar wormholes];
    James et al AJP(15)-a1502 [visualization];
    Dai & Stojkovic PRD(19)-a1910 [how to observe];
    Simonetti et al a2007 [search, test of triple system].
  @ Formation: Hyun et al a0705-wd [from gravitational collapse];
    Savelova & Kirillov a1405 [artificial wormhole];
    Horowitz et al CQG(19)-a1904 [nucleating a traversable wormhole];
    Dai et al a2010 [simple formation model].
  @ And galaxies: Bambi PRD(13)-a1304 [and galactic centers];
    Rahaman et al EPJC(14)-a1307 [in the galactic halo?].
  @ Quasinormal modes:
    Konoplya & Zhidenko PRD(10)-a1004 [and scattering properties];
    Konoplya & Zhidenko JCAP(16)-a1606 [ringing, vs black holes];
    Konoplya PLB(18)-a1805 [and shape of the wormhole].
  @ Particle and field propagation:
    González-Díaz PRD(97)gq [on electromagnetic waves];
    Strokov & Repin a0709/G&C [perihelion precession and light deflection];
    Shatskiy PU(09)-a0809 [characteristic features of images];
    Pozanenko & Shatskiy G&C(10),
    a1007
      [search for observational evidence in GRBs, soft-gamma repeaters];
    Sarbach & Zannias AIP(12)-a1204;
    Tsukamoto et al PRD(12)-a1207 [lensing and Einstein-ring systems, vs black holes];
    Li & Bambi PRD(14)-a1405,
    Narzilloev et al a2105 [distinguishing black holes and wormholes];
    > s.a. black-hole formation;
      types of dark matter.
Classical and Semiclassical Aspects > s.a. casimir effect;
  gravitational self-force; holography;
  quantum field theory effects [negative energies].
  * Traversibility:
    It is accompanied by unavoidable violations of the weak energy condition ("exotic matter").
  @ Framework:
    Friedman et al PRD(90) [Cauchy problem];
    Hayward IJMPD(99)gq/98,
    gq/03-conf [dynamical laws].
  @ And time machines:
    Frolov & Novikov PRD(90);
    Echeverría et al PRD(91);
    Antonsen & Bormann qp/96-proc;
    Aref'eva & Volovich IJGMP(08)-a0710 [production at the LCH].
  @ Thermodynamics:
    Hong & Kim MPLA(06) [T < 0];
    Martín-Moruno & González-Díaz CQG(09) [laws, thermal emission];
    Bandyopadhyay et al IJTP(15)-a1211.
  @ Other theoretical effects: Hochberg & Visser PRL(98)gq [null energy condition violation];
    Cox et al a1109 [statistical mechanics of a gas of wormholes];
    Olmo et al a1601-MG14 [as a cure for black-hole singularities];
    Bejarano et al EPJC(17)-a1607 [and energy conditions].
  @ Quantum field theory on wormhole background:
    Khatsymovsky PLB(94);
    Bezerra et al PRD(10) [massive scalar, vacuum stress-energy].
  @ Semiclassical: Hawking NPB(91) [effective action];
    Hochberg et al PRL(97)gq;
    Khusnutdinov & Sushkov PRD(02)ht [massive scalar];
    Khusnutdinov PRD(03);
    Garattini CQG(05)gq [self-consistent to graviton 1-loop];
    Buniy & Hsu PLB(06)ht/05 [instability];
    Garattini & Lobo CQG(07)gq [phantom].
  @ And chronology protection: Visser PRD(97)gq.
Quantum Aspects > s.a. entanglement in quantum
  field theory; kaluza-klein models [higher-dimensional dyons].
  * Motivation: Used to explain the
    smallness of the cosmological constant, and as a mechanism for loss of coherence.
  @ General references: Visser PRD(91),
    MPLA(91) [Planck-size throat];
    González-Díaz MPLA(93);
    Hochberg PRD(95)gq [Lorentzian].
  @ And constants of nature:
    Hawking NPB(90);
    > s.a. quantum gravity and cosmology [including cosmological constant].
  @ And quantum gravity:
    Hawking MPLA(90),
    MPLA(90) [baby universes];
    Kunstatter et al PRD(10),
    PRD(11)-a1010 [Einstein-Rosen throat];
    Kuhfittig IJPAM(13)-a1301 [in non-commutative geometry];
    > s.a. FLRW quantum cosmology; minisuperspace;
      quantum regge calculus; spacetime foam.
  @ Black hole pair creation: Garattini NCB(98)gq/96;
    González-Díaz IJMPD(97)gq/96.
  @ Related topics:
    Coleman & Lee NPB(90);
    Hawking & Page PRD(90) [spectrum];
    González-Díaz PRD(90) [coherence];
    Ellis et al PLB(90),
    Moss Nat(90)feb [in SQUIDs];
    Garfinkle & Strominger PLB(91) [instanton for pair of Reissner-Nordström black holes];
    Coleman & Hughes PLB(93) [global charge];
    Cavaglià MPLA(94) [Kantowski-Sachs];
    Lee & Kim PLB(04) [2D dilaton + ghost Klein-Gordon];
    Santini qp/07-MGXI,
    EPL(07)qp [as origin of EPR correlations];
    Garattini CQG(07) [traversable, and equation of state];
    Engelhardt et al PRD(15)-a1504 [electric fields threading quantum wormholes];
    Mateos & Sabín PRD(18)-a1706 [quantum simulation in a BEC].
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