Interpretations of Quantum Theory  

In General > s.a. Epistemology; foundations and history of quantum mechanics; Interpretation of a Theory; types of interpretations.
* Idea: Provide an answer to the question, How can the world be for quantum theory to be true? Not so many valid interpretations of quantum mechanics are known, but each one provides insight into a different aspect of the theory, and often also practical benefits.
* Distinction: One of the main distinctions is between epistemic and ontic interpretations; > s.a. ψ-Epistemic Theories; ψ-Ontic Theories.
@ Reviews: DeWitt & Graham AJP(71)jul [RL]; Pearle & Valentini in(06)qp/05 [realist]; Berche et al phy/06 [history]; Marchildon in(07)qp/06; Blood a1001 [primer]; Ruetsche 11 [r Healey PhSc(13)]; Grib PU(13)-a1404; Boyer-Kassem a1509; Nikolić a1703 [concise and simple]; Chen a1810 [realist].
@ General references: Whitaker & Singh JPA(82) [and the EPR paradox]; McCarthy & Weigold AJP(83)feb; Dieks Syn(91); Mermin Pra(98)qp/96; Svozil qp/02 [need]; Neumaier qp/05 [challenge]; Vermaas BJPS(05) [conditions]; Kitajima IJTP(05) [in terms of beable algebras]; Rau PE(06)qp; Lazarou a0712; Grinbaum PhSc(07)dec [vs reconstruction]; Marchildon a0902-proc; Ghirardi a0904; Fields a1004 [and decompositional equivalence]; Herbut a1108 [collapse vs no-collapse interpretations]; Lokajíček et al a1305; Forte Eur-a1309 [high-energy interpretation]; Ellerman a1401 [objective indefiniteness]; Tammaro a1408; Dorato Synth(15)-a1503; Frank NYAS-a1604 [inability to experimentally distinguish between interpretations]; in Poirier PRX(16); Dick SHPMP-a1703 [superpositions and the need for quantum field theory]; Baumann & Wolf a1710; Cabello et al a1901 [thermodynamical cost of some interpretations]; Suarez a1905 [Principle Q]; Helland a1905 [based on statistical inference]; Fröhlich a1905-in [ETH Approach]; Marchildon a1906 [and reality]; 't Hooft a2104 [unorthodox view].
@ Classification, comparison: Margenau PT(54)oct [comparison]; Görnitz & von Weizsäcker IJTP(87) [comparison]; Hartle in(05)qp/03 [connections]; Putnam BJPS(05) [and exclusion of Copenhagen and many-worlds]; Cabello in(17)-a1509 [types, and need to make progress]; Krizek a1707 [classification scheme]; Oldofredi & Lopez a2006 [ψ-ontic vs ψ-epistemic]; Drezet a2105 [nomic and anomic].
@ Meaning of interpretation: Beneduci & Schroeck AJP(14)jan-a1211; Muller a1406-fs; Healey BJPS(15)-a1110 [explaning phenomena]; Drieschner a2007.
@ Points of view: Ballentine AJP(72)dec, Deltete & Guy AJP(90)jul [Einstein's]; Pippard EJP(86) [wave function reduction just bookkeeping procedure]; Fuchs & Peres PT(00)mar, Skála & Kapsa qp/04, refutation Oldofredi a1904 [no interpretation needed]; Dennis & Norsen qp/04 [unavoidability]; Blood a0910; Friederich SHPMP(11)-a1101 [proposal regarding the main challenge for epistemic interpretations], SHPMP(13)-a1204 [defense of non-ontic interpretations]; Beneduci & Schroeck AJP(14)jan [unavoidability]; blog sn(14)feb; Zeh a1402-in [John Bell's]; Wüthrich a1406-in [re need for interpretation]; Leuchs a1501-conf; Vassallo & Esfeld FP(15)-a1504 [importance]; Bezlepkin a1602 [reason for the diversity]; Bricmont & Goldstein JSP(19)-a1804; Boughn a1912 [why are we obsessed with "understanding"?]; de Ronde a2008 [no need].
blue bullet Related topics: see Equivalence Relation; interference; mixed states; non-linear quantum mechanics; Ontology; QBism; quantum computing.

Standard (Copenhagen) # Bohr; Summary-motto "Quantum mechanics is correct; Nature is not crazy; So quantum mechanics is not crazy".
* Idea: A pure state provides a complete and exhaustive description of an individual system, that is expressed in a probabilistic form; When we make a measurement, the wave function collapses on an eigenstate of the measured quantity with eigenvalue equal to the value obtained.
@ General references: in Messiah 62; de Broglie 64; Hall AJP(65)aug; Stapp AJP(72)aug, comment Ballentine AJP(74)jan, reply Stapp AJP(74)jan; in Peierls 79; Lahti & Mittelstaedt ed-87; Santos FP(91) [realism, hidden variables, and Bell inequalities]; Cushing 94 [history]; Kober a0905 [philosophical]; Henderson SHPMP(10) [versions]; Hollowood CP(16)-a1511 [early ideas and later insights]; Fuchs a1809-AJP.
@ Points of view: Wheeler in(86) [weak realism]; Beller PhSc(96)jun [against anti-realism]; Shi AdP(00)qp/98 [against]; Lokajíček qp/06 [criticism of supporting arguments]; de Muynck AIP(07)-a0710 [limitations, and 'neo-Copenhagen']; Schmelzer a0909 [problem with the symmetry group of a quantum theory]; Hollowood JPA(13)-a1302, JPA(14)-a1312 [as an emergent phenomenon]; Hollowood a1411.
@ Relationships: Peres SHPMP(02)qp/99 [vs Popper]; Gomatam PhSc(07)dec [vs Bohr's]; Lokajíček AIP(08)-a0711 [vs hidden varables]; Susskind a1604-talk [duality with Everett's interpretation, and the ER = EPR conjecture].
@ And decoherence: Kiefer qp/02-fs; Fujii a1304.
@ Related topics: Gillespie AJP(89)dec; Stuart FP(91), Diósi qp/99-in [modified]; in Sorkin IJTP(97)gq; de Muynck FP(04)qp/03 [neo-Copenhagen]; Howard PhSc(04)dec [historical development]; Ghirardi et al PRA(07)qp [re experiment to test it]; > s.a. quantum cosmology.

Statistical (Ensemble) > s.a. foundations [single system].
* Idea: An epistemic interpretation, in which a state describes an ensemble of equally prepared systems, not an individual one; > s.a. ψ-Epistemic Theories.
* Advantages: The most "sober" one; It does not require a wave-function collapse, and admits that quantum mechanics may be "completed".
@ General references: Kemble PR(35); Einstein in(49); Margenau PhSc(63)apr; Pearle AJP(67)aug; Ballentine RMP(70); Krips AJP(75)may; Newton AJP(80)dec; Pais Sci(82)dec; Kunstatter & Trainor AJP(84)jul, Gillespie AJP(86)oct [simple ensemble interpretation untenable]; Tschudi HPA(87); Ballentine IJTP(88); Bohm & Hiley PRP(89); Home & Whitaker PLA(91) [and København], PRP(92); Gottfried qp/98; Mielnik FP(94) ["problem"]; Shirai FP(99); Whitaker FP(08) [re Bell and Gottfried]; Smolin FP(12)-a1104 [new version]; Lewis et al PRL(12)-a1201 [test with models]; Pomeau & Le Berre a1810 [rev and example]; Shaiia a2003 [enhanced version].
@ PBR theorem: Pusey et al nPhys(12)may-a1111 + news nat(12)may [inconsistency of the interpretation, and proposed tests], comment Hofmann a1112, Drezet a1203; Drezet PiP-a1209, a1209; Emerson et al a1312 [refutation of the proof].
@ Related topics: Merli et al AJP(76)mar [electron interference]; Home & Whitaker PLA(86) [and context-dependence]; Sanctuary qp/04 [entangled states].

Modal Interpretation > s.a. many-worlds interpretation; quantum measurement.
* Idea: (Kochen, Dieks, ...) A realistic interpretation without the world view of classical mechanics; Quantum mechanics does not provide an account of what 'actually is the case', but rather deals with what 'might be the case', i.e., with possibilities; It abandons the eigenstate-eigenvalue rule of standard quantum mechanics to avoid the measurement problem without introducing hidden variables; Collapse corresponds to a change from discussing the theoretical state of a system (which specifies probability distributions) to discussing the physical state (which assigns values to observables).
@ Books, reviews: van Fraassen 91; Dieks & Vermaas ed-98; Vermaas 00.
@ General references: Dieks FP(89), PLA(95); Clifton BJPS(95) [motivation], BJPS(96) [properties]; Dickson BJPS(95) [and projection postulate]; Vermaas & Dieks FP(95); Vermaas PRL(97); Zimba & Clifton in(98)qp; Bacciagaluppi & Dickson FP(99) [dynamics]; Bacciagaluppi FP(00); Spekkens & Sipe qp/00; Dieks SHPMP(07)qp [probabilities]; Domenech et al a0705/SHPMP [contextual character]; Ardenghi et al FP(09), Lombardi et al SHPMP(10) [and Galilean transformations]; Terekhovich a1909.
@ Modal-Hamiltonian interpretation: Lombardi & Castagnino SHPMP(08)-qp/06; Lombardi et al PhSc(11) [and environment-induced decoherence]; Lombardi et al Ent(15)-a1603 [informational perspective].
@ Other variations: Hollowood a1312 [new, improved modal interpretation]; Barandes & Kagan a1405, a1405, a1807 [minimal modal interpretation].
@ Classical, macroscopic behavior: Bene qp/01; Bene & Dieks FP(02)qp/01.
@ Difficulties: Leeds & Healey PhSc(96)mar; Myrvold FP(02)qp, Berkovitz & Hemmo FP(05), PhSc(05)dec, Earman & Ruetsche PhSc(05)oct [Lorentz invariance].
@ In quantum field theory: Dieks PLA(00)qp/99 [and consistent histories]; Clifton PLA(00)qp; Bene qp/01; Kitajima PLA(04) [algebraic]; Myrvold BJPS(09) [difficulties]; Ardenghi et al IJTP(11).
@ Other extensions: Nakayama IJTP(08)-a0711 [topos-theoretic]; Ardenghi et al IJTP(10)-a1012 [relativistic quantum mechanics].

"Shut up and calculate" – attributed to R Feynman [but see Mermin PT(04)may]

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