Time in Physical Theories  

In General > s.a. time [different views, general aspects].
* Two-time physics: The theory proposed by Itzhak Bars and collaborators has one extra timelike and one extra spacelike dimension (4+2); Claimed to be free of problems with unitarity and causality, and to explain CP conservation in QCD without the need for the axion, among other things.
@ Parametrized theories: Hartle & Kuchař in(84); Magnon NCB(96), NCB(98) [relational]; Albrecht & Iglesias PRD(08)-a0708 [emergent]; Rañada & Tiemblo FP(08); Gryb & Thébault FP(12)-a1110 [relational]; Höhn JPCS(12)-a1110 [effective approach, semiclassical regime]; Anderson CQG(14)-a1305; Gueorguiev a1903-conf [Lagrangian and extended Hamiltonian formalism]; > s.a. Relationalism; time in gravity.
@ Two-time physics: Bars PRD(00)ht, PRD(00)ht [in field theory], CQG(01)ht/00 [survey]; Bars & Deliduman PRD(01)ht [particle + gauge field]; Bars PRD(06)ht, AIP(07)ht/06 [and standard model]; Chagas ht/06 [with minimum length]; news pn(07)jun; Bars & Kuo PRL(07) [with N = 1 Supersymmetry]; Chagas a0802 [in quantum mechanics]; Craig & Weinstein PRS(09) [initial-value problem]; Foster & Müller a1001 [general properties]; Frederico & Rivelles PRD(10) [transition amplitudes]; Caruso a1405 [on proving the one-dimensionality of time]; > s.a. black holes in modified theories; brane world; higher-dimensional gravity; kaluza-klein theory; time in gravity and quantum gravity.
@ Multi-time physics: (one for each particle) Petrat & Tumulka PRS(14) [classical and quantum]; > s.a. Pair Creation.
@ Complex time: Mejías et al CSF(04); Fujii qp/07-conf [comment on a paper by Rajeev].
@ Different views: Oleinik et al qp/00-conf [dynamical inhomogeneity]; Lynds FPL(03); Sadatian ILCPA-a1404 [inhomogeneous time?].
> Other theories: see time in gravitational theory; time in quantum theory; time in quantum gravity.

In Classical Mechanics
* Idea: In its usual presentation, classical mechanics appears to give time a very special role, but it is well known that it can be formulated so as to treat time on the same footing as the other variables in the extended configuration space.
@ General references: Muñoz-Díaz & Alonso-Blanco a1707 [and quantum mechanics].
@ As a dynamical variable: Grigorescu CJP(00)mp [canonical]; Bhamathi & Sudarshan PLA(03); Rañada & Tiemblo CJP(12)-a1106 [parameter time vs physical time].
@ In thermodynamics: da Costa & Sant'Anna FPL(01)gq, mp/01, FP(02) [thermodynamics without t].
@ Discrete time: Jaroszkiewicz & Norton JPA(97); Jaroszkiewicz 14 [and in quantum mechanics, field theory].
@ Related topics: Wetterich FP(12)-a1002 [probabilistic]; Thébault BJPS(12) [and symplectic reduction].

In Special Relativity > s.a. special relativity.
* Idea: Time loses the uniqueness it had in classical mechanics; It is no longer a specific function, but just a measure of timelike distance along some worldline; The direction of time is now defined up to a Lorentz transformation.
* Clock hypothesis: The assumption that the time read by an accelerated clock is given by the elapsed Minkowski proper time, i.e., the length of the timelike curve.
@ General references: Rodrigues & Rosa FP(89); Kobe AJP(93)nov [parametrizations]; Selleri FP(97); Lindesay & Gill FP(04) [proper τ]; Ya'acov JPA(06) [internal time]; Boyarsky & Gora a0705 [time measurement definition using fundamental scale]; Paiva & Teixeira a1107 [and general relativity; in Esperanto/English]; Chappell et al a1205 [time identified with the three rotational degrees of freedom of space, and Clifford's geometric algebra]; Bacelar a1302, Fletcher FP(13) [time for accelerated observers and the clock hypothesis]; Bacelar a1312 [flow of time]; Brunet a1609 [geometric time and causal time]; Bacelar a1610 [inertial time, light clocks].
@ Effects: Goy & Selleri FPL(97)gq [rotation]; Bahder gq/98 [rotating clock]; Leffert ap/02/MNRAS [running backwards??].

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