Causality Violations  

In General > s.a. information; wave phenomena.
* Ways to violate causality: Superluminal local travel from classical physics (tachyons, ...), due to quantum effects (quantum tunneling, quantum field theory effects), "global" effects due to non-trivial spacetime topology (wormholes, Misner space, ...); Superluminal travel requires violations of the averaged null energy condition.
@ General references: issue disc(89)jun; Nahin 98; Gott 01; Davies 01; Toomey 07 [r pw(08)jan].
@ Philosophical: Smith BJPS(97) [slipping on banana peels]; Dowe PhSc(03) [coincidences]; Raju FP(06)-a0804 [time travel and spontaneity].

Classical, Local Superluminal Signaling and Travel > s.a. causal; tachyons; wave phenomena.
@ Books: Fayngold 02; Tiwaru 03.
@ General references: Svozil PLA(95) [paradoxes]; Recami et al IJMPA(00) [and special relativity]; Recami FP(01)phy [review]; Zhou PLA(00) [vg > c, numerical]; Fayngold 02; Liberati et al AP(02)gq/01 [Scharnhorst effect]; Van Flandern & Vigier FP(02) [support]; Lobo & Crawford LNP(03)gq/02 [definitions]; Krasnikov PRD(03)gq/02 [quantum inequalities and shortcuts]; Buenker SJCP(04)phy [??]; Nimtz FP(04); Bonvin et al a0706 [superluminal motion and causality].
@ Specific theories: Hashimoto & Itzhaki PRD(01) [solitons in non-commutative gauge theory]; Borghardt et al PLA(03)qp [vg > c in Klein-Gordon]; González-Mestres ap/04-in [non-tachyonic "superbradyons"]; > s.a. Pauli-Fierz Theory.

Non-Causal Spacetimes > s.a. gödel; Misner Space; types of spacetimes [3D flat]; wormholes.
@ General references: Tipler PRD(74), PRL(76); Penrose in(79); Thorne in(91); Deser & Steif gq/92 [3D results]; Blau AJP(98) [and topology change]; Romero & Torres MPLA(01)gq [consistency]; Garay & González-Díaz GRG(01) [and quantum gravity]; Bonnor IJMPD(03)gq/02 [conceptual]; Lobo & Crawford gq/02-in [rev]; Shore IJMPA(03)gq/02 [rev]; Susskind gq/05 [unlikely], rebuttal gq/05; Monroe gq/06 [and topology].
@ Examples: Chamblin et al PRD(94), Yurtsever GRG(05)gq/94 [Politzer spacetime]; Caldarelli et al JHEP(01) [in AdS5]; Bonnor CQG(02) [asymptotically flat example], Rebouças & Teixeira IJMPA(98)gq [Kaluza-Klein theory]; Olum & Everett FPL(05) [re circulating light beam]; Bonnor & Steadman GRG(05) [Einstein-Maxwell]; Rosa & Letelier a0706 [cylindrical with spinning sources, stability of closed timelike curves].
@ Initial value problem: Friedman & Morris PRL(91), in(91); Fewster et al PRD(96)gq; Friedman gq/04-in [rev].
@ Chronology protection: Hawking PRD(92); Visser PRD(93), NPB(94)ht/93; Cassidy & Hawking PRD(98)ht/97 [models]; Huang PRD(99)ht/02 [in Gödel spacetime]; Hiscock gq/00; Visser gq/02-in [re]; Friedman & Higuchi AdP(06), a0801 [rev]; Monroe gq/06 [censorship]; Segre gq/06 [comment]; > s.a. wormholes.
@ And singularities: Maeda & Ishibashi PRD(97) [spatially compact].
@ And energy conditions: Ori PRL(91), PRL(93); Olum PRL(98)gq; Visser et al NPPS(00)gq/98; Baird gq/99.
@ Paradoxes: Krasnikov PRD(97)gq/96, PRD(02)gq/01; Dowe PhSc(07); > see in quantum mechanics below.
@ Related topics: Cooperstock & Tieu gq/04, FP(05) [misconceived article?]; Hadley gq/06-in [and quantum theory]; Durham a0803 [and quantum information]; > s.a. klein-gordon fields.

Time Machines > s.a. wormholes [including Krasnikov tube].
@ General references: Novikov JETP(89); Krasnikov CQG(94), PRD(96)gq/95 [quantum stability], CQG(98)gq/97 [singularity-free], PRD(98)gq/95, PRD(99)gq/98 [and quantum field theory], CQG(02)gq/01 [no-go in classical general relativity], gq/03-in [rev]; Carlini et al IJMPD(95), Carlini & Novikov IJMPD(96) [self-consistency]; Low CQG(95); Woodward FPL(95); Davies SA(02)sep; Krasnikov gq/06 [intro].
@ Gott time machines: Gott PRL(91) [moving cosmic strings]; Carroll et al PRL(92), Deser et al PRL(92) [obstacles]; Holst GRG(96)gq/95 [in AdS]; Birmingham & Sen PRL(00) [BTZ black holes and scaling].
@ Warp drive: Alcubierre CQG(94)gq/00; Pfenning & Ford CQG(97)gq [unphysical]; Coule CQG(98); Low CQG(99) [need for exotic matter]; Clark et al CQG(99)gq [null geodesics]; González-Díaz PRD(00)gq/99 [stability]; Van Den Broeck CQG(99)gq; Loup et al gq/01, gq/02; Hart et al gq/02 [hazards]; White GRG(03) [mechanism]; Lobo & Visser CQG(04)gq [limitations], gq/04-in [linearization, energy]; Ellis gq/04 [and antigravity]; González-Díaz PLB(07) [superluminal]; Obousy & Cleaver a0712-JBIS [and extra dimensions]; > s.a. quantum field theory effects [negative energy].
@ Production in experiments: Mironov et al in(06)-a0710, Aref'eva & Volovich IJGMP(08)-a0710 [LHC].
@ Other examples: González-Díaz PRD(98)gq/97 [quantum]; DeDeo & Gott PRD(02) [2+1 AdS]; Charette et al JGP(03)m.DG/02 [closed timelike curves in flat 3D]; Ori PRL(05)gq [compact vacuum core], PRD-gq/07 [development from regular initial surface].

In Quantum Mechanics > s.a. hidden variables; locality; quantum effects, experiments [superluminal], and measurement [non-local].
@ Superluminal communication: Michalski qp/99-wd; Kuzmich et al PRL(01) [and quantum noise]; Yang qp/01; Griffiths PRA(02)qp [no problem]; Ferrero et al PRA(04) [and non-linearity]; Malikotsinas qp/04 [and entanglement]; Ferrero et al IJQI(05)qp [and non-linear evolution]; Pankovic et al qp/05 [Griffiths' bug shadow]; Bassi & Ghirardi a0711 [not possible with wave function collapse].
@ Superluminal tunneling: Aharonov et al PRL(98)qp [and unstable states]; Chiao qp/98; Ghose & Samal PRE(01)qp/00 [and special relativity]; Muga et al qp/02 [Hartman effect]; Sokolovski PRS(04)qp/03; > s.a. tunneling.
@ Causality violations: Bennett PRA(87), PRA(87) [evidence in Compton scattering]; Valentini PRL(88); Vaidman FP(91); Gray qp/98-wd [time machine]; Greenberger & Svozil in(02)qp/05 [beam splitter model, paradox resolution], comment Wykes qp/05; Pegg qp/05-in [and self-consistency].
@ And unitarity: Anderson PRD(95)gq/94; Antonsen & Bormann IJTP(98)qp; Everett PRD(04)gq [many-worlds]; Cornalba & Costa PRD(06).
@ Quantum mechanics with closed timelike curves: Hartle PRD(94)gq/93 [and unitarity]; Fewster & Wells PRD(95)ht/94; Politzer PRD(94)gq; Rosenberg PRD(98)ht/97.
@ Computing with closed timelike curves: Deutsch PRD(91); Brun FPL(03)gq/02; Bacon qp/03; > s.a. quantum computation.

In Quantum Fueld Theory > s.a. quantum field theory in curved backgrounds; modified QED; violations of lorentz symmetry.
* Idea: QED vacua, for example, become dispersive media under the influence of external conditions (background fields, curvature, non-trivial boundary conditions, finite temperature), and may produce superluminal effects; 2001, In curved spacetime, whether there can actually be causality violation (vfront > c) remains an open question.
@ Superluminal photon in curved spacetime: Khriplovich PLB(95); Daniels & Shore PLB(96); Dolgov & Novikov PLB(98)gq; Konstantinov gq/98; Shore gq/03-in, CP(03)gq; Hollowood & Shore PLB(07)-a0707, NPB(08)-a0707 [QED].
@ Other topics: Hawking PRD(95)gq [loss of quantum coherence]; Jain & Joglekar IJMPA(04)ht/03 [non-local 4]; Nielsen & Ninomiya a0802 [at the LHC]; Dubovsky & Sibiryakov a0806 [in 2D quantum field theory with broken parity].


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