Causality Violations  

In General > s.a. Action at a Distance; information; Superluminal Communication / Travel; 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]; Lobo ch-a1008 [rev]; Polonyi PRD(11)-a1109 [dynamical breakdown]; Wüthrich a1907-in [in the emergent spacetime of quantum gravity].
@ Detection: Haque & Joglekar JPA(09)-a0808 [non-local scalar model].
@ Philosophical: Smith BJPS(97) [slipping on banana peels]; Dowe PhSc(03)jul [coincidences]; Raju FP(06)-a0804 [time travel and spontaneity].

blue bullet Related topics: see causality violations in quantum theory [including time travel, indefinite causal structures]; non-causal spacetimes.

Spacetimes with Closed Timelike Curves / Time Machines > s.a. wormholes [including Krasnikov tube].
* Warp drive: A spacetime in which a flat warp bubble moves, preceded by a region of contracting spacetime and followed by one of expanding spacetime; A spaceship inside the bubble, although locally moving slower than light, could reach its destination faster than a light beam travelling outside the warp bubble; However, warp drives are quantum-mechanically unstable because they produce unboundedly blueshifted Hawking-like radiation at their front wall.
@ 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-conf [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]; Al-Khalili 11; González-Díaz PRD(12), Devin a1302 [thermal properties]; Everett & Roman 13; Arefeva et al PRD(16)-a1508 [holographic dual]; Neves a1709 [philosophical argument against]; Tobar & Costa CQG(20)-a2001 [complex dynamics without inconsistencies]; Luminet Univ(21)-a2101 [historical survey].
@ 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-proc [linearization, energy]; Ellis gq/04 [and antigravity]; González-Díaz PLB(07) [superluminal]; Obousy & Cleaver JBIS-a0712 [and extra dimensions]; Finazzi et al PRD(09)-a0907, Barceló et al a1001-FQXi [semiclassical instability]; Müller & Weiskopf GRG(12)-a1107 [null and timelike geodesics]; Coutant et al PRD(12)-a1111 [instability with Lorentz-invariance violation]; McMonigal et al PRD(12)-a1202 + news cosmos(12)mar [interaction with massive particles]; Varieschi & Burstein ISRN(13)-a1208 [in conformal gravity]; blog(12)nov, blog(14)jun [is it possible?]; Liberati a1601-GR14 [pre-emptive superluminal warp drive destabilization]; Alcubierre & Lobo FTP(17)-a2103; Bobrick & Martire CQG-a2102 [physical]; > s.a. quantum field theory effects [negative energy]; David Waite's page; Wikipedia page.
@ Production in experiments: Mironov et al in(06)-a0710, Aref'eva & Volovich IJGMP(08)-a0710 [LHC].
@ Other spacetimes with closed timelike curves: González-Díaz PRD(98)gq/97 [quantum]; DeDeo & Gott PRD(02) [2+1 Anti-de Sitter]; Charette et al JGP(03)m.DG/02 [closed timelike curves in flat 3D]; Ori PRL(05)gq [compact vacuum core], PRD(07)gq [development from regular initial surface]; Manchak SHPMP(11); Elze EPJW(13)-a1310 [and discrete mechanics]; Mulder & Dieks a1704 [determinism and indeterminism]; Ghosh et al QIP(19)-a1708 [integer factorization], QIP-a1708 [cryptographic protocols]; Hazarika a2004 [axially symmetric]; Paganini a2005 [nothing happens].
@ Related topics: news sn(14)jan [search fails to find evidence for time travelers].

Note to time travelers: You are all welcome to the party that Stephen Hawking hosted in 2009.

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