Multiverse Cosmology  

Multiple Universes in General > s.a. Baby Universes; cosmology.
* Level 1: Regions beyond our cosmic horizon (same laws and constants).
* Level 2: Other post-inflation bubbles (same laws, different constants) and disconnected regions; Includes "black hole babies", with natural selection related to the anthropic principle, as in Smolin's ideas (values of constants of nature are adjusted to maximize black hole production), baby universes as in quantum cosmology, and the various possibly interacting branes in the brane scenario; > s.a. Bubbles.
* Level 3: The many world (parallel universes) of quantum physics; > s.a. many-worlds interpretation.
* Level 4: Other mathematical structures and laws of physics.
@ Books, I: Krauss 06 [alternate realities]; Vilenkin 06; Manly 11.
@ Introductions, reviews: Tegmark SA(03)may, in(03)ap [levels]; Ellis et al MNRAS(04)ap/03; Davies MPLA(04)ap; McCabe gq/06 [various notions]; Barrau CERN(07)-a0711 [intro rev]; Vaas a1001/JCosm; Ellis SA(11)aug; Sheldon CP(12); news SA(13)jun; Wilczek CQG(13)-a1307; news wired(14)nov; Linde a1512 [inflationary multiverse, different low-energy laws of physics]; Gangui AAFA(20)-a2009.
@ General references: Deutsch PRS(02)qp/01 [information in multiverse]; Bjorken ap/04/PRD; Bettini Kairos-phy/05 [history]; Weinberg ht/05-conf; Davies ap/06-conf [the problem of what exists]; Carr ed-07; González-Díaz et al G&C(10)-a0705 [as resolution of some problems]; Hall & Nomura PRD(08)-a0712 [argument in favor from unnaturalness]; Mersini-Houghton a0804, a0809-ch [and initial conditions]; news sn(09)jun [Origins symposium]; Smolin pw(09)jun [criticism]; Gribbin 10; Soler & Alfonseca JGPS(13)-a1105 [experiments with cellular automata]; Greene 11; Nomura AstRev-a1205; news nbc(12)dec; Siegfried 19 [history].
@ Level 1: Scott & Zibin IJMPD(06)ap [how many are there?]; Page a0801-talk [and Christian theology]; interview npr(11)jan.
@ Philosophical, conceptual: Stoeger et al ap/04; Hall a1306; Sangalli a1607 [critical view]; Friederich PRD(17)-a1707 [observer typicality]; Carroll a1801-in [conventionally scientific]; Alonso-Serrano & Jannes Univ(19)-a1910; Friedrich 21.
@ Level 2: Markov PLA(90); Garriga & Vilenkin PRD(01)gq [different regions from inflation]; McCabe FPL(05) [topology of branching universes]; Aganagic et al NPB(07)ht/06 [entanglement of baby universes]; Aguirre et al PRD(07)-a0704 [bubble collisions and observations]; Ferrando et al PRD(07)-a0706 [creatable universes, with vanishing conserved quantities]; Ansoldi & Guendelman PTP(08)-a0706 [with arbitrarily small energy cost]; Placek & Müller SHPMP(07) [branching spacetimes]; Vilenkin & Vanchurin PRD(10)-a0910 [inflation, number of distinguishable locally-Friedmann universes]; Dahlen PRD(10) [observability]; Robles-Pérez & González-Díaz a1111 [quantum entanglement]; Vilenkin & Zhang JCAP(14)-a1403 [past incompleteness]; news sa(14)mar [renewed debate after BICEP2 results]; Donoghue ARNPS(16)-a1601 [rev]; > s.a. brane-world scenarios; cosmological perturbations; inflationary scenarios; wormholes [baby universes].
@ Level 3: Tegmark in(10)-a0905 [objections to Everett's theory and parallel universes]; Dugić & Jeknić-Dugić a1004, a1007; Robles-Pérez & González-Díaz PRD(10) [third-quantization formalism]; Robles-Pérez a1211-ch, AIP(13)-a1212 [entangled pairs of universes]; Aharonov et al in(14)-a1305 [time evolution as correlations between universes]; Kanno PLB(15)-a1506 [entanglement between causally disconnected universes]; McKenzie a1602 [mathematical structure]; > s.a. entangled systems; Third Quantization.
@ Anthropic reasoning: Aguirre & Tegmark JCAP(05)ht/04 [and coincidences]; Weinstein CQG(06)ht/05; Page PLB(13)-a1101 [evidence against simple form of wave function collapse]; Kawai & Okada PTP(12)-a1110 [solving the naturalness problem by baby universes without the anthropic argument].
@ And life: Rubin CSF(02)ap; Jenkins & Perez SA(10)jan; Gleiser IJMPD(10) [primitive vs complex life]; Adams et al JCAP(15)-a1505 [parameter values that allow for habitable planets]; Adams JCAP(16)-a1511 [stars and habitable planets with different fundamental constants]; Galántai a1607; Livio a1801-in.
@ Cosmic natural selection, fine tuning: Smolin CQG(92), gq/94, 97; Vaas gq/02-proc; Smolin PhyA(04); Susskind ht/04 [comments]; Vilenkin ht/06 [objection to argument]; McCabe gq/06 [extension]; Smolin ht/06 [status and comments]; Palonen a0802 [Bayesian considerations].

Statistical Cosmology > s.a. civilizations.
* Idea: Gell-Mann coined the term "multiverse"; The "principle of mediocrity", a version of the anthropic one, states that we are a typical civilization in the multiverse.
* Setup: The probability that the constants of nature have values c = {cj} is Pc = wc Nc, with wc the probability for a random universe to have values c, and Nc the number of civilizations with values c (assume a finite inflation) = Vc Kc, with Vc the volume at the end of inflation, and Kc the "number of civilizations per unit volume".
@ Probabilities and predictions: Vilenkin ht/06; Garriga & Vilenkin PRD(08)-a0711; Freivogel CQG(11)-a1105 [rev]; Garriga & Vilenkin JCAP(13); > s.a. probability in physics [propensity]; Azhar CQG(14)-a1506, PRD(15)-a1506 [and typicality]; Urbanowski a1509; Azhar a1609-proc [and typicality].

Other Issues > s.a. anthropic principle; arrow of time; quantum non-locality; variation of constants.
* The measure problem: How to obtain normalized probabilities of observations from the (quantum) state of the universe.
@ Physical constants: Gouts G&C(03)gq/02; Vilenkin PRL(95)gq/94, PRD(95)gq, gq/95-conf [and quantum cosmology, inflation].
@ Phenomenology, predictions: Aguirre ap/05-ch; ap/06 [retroductive tests]; Page in(07)ht/06; Aguirre & Johnson PRD(08)-a0712 [bubble universes]; Larsen et al PRD(11)-a1107 [value of the cosmological constant]; Adams & Grohs APP(17)-a1608 [stellar He burning in other universes]; Barnes a1704 [Bayesian approach to testing the multiverse]; Dabrowski Univ(19)-a1910.
@ Measure on the multiverse: Gibbons & Turok PRD(08)ht/06; Vilenkin JPA(07)gq/06, JHEP(07); Schwartz-Perlov & Vilenkin JCAP(10)-a1005 [probability measure for a transdimensional universe]; Vilenkin AIP(13)-a1301; Vilenkin JCAP(14)-a1312 [quantum watcher measure]; Page JCAP(14)-a1406 [Spacetime Average Density measures]; > s.a. Boltzmann Brains; canonical quantum gravity; loop quantum gravity; path-integral quantum gravity; quantum cosmology.
@ Level II, bubble universes: Kleban et al PRD(13) [collisions, observational evidence]; Wainwright et al JCAP(14)-a1407; Takamizu & Maeda PRD(15)-a1504 [with different gravitational constants]; Garriga et al JCAP(16)-a1512 [and black holes].
@ Quantum multiverses: Nomura PRD(12)-a1205 [the quantum multiverse state must be static]; Hartle a1801.
@ Other observation, experiments: Palesheva MSM(02)qp, G&C(03) [particle interference]; Donoghue in(07)-a0710 [and particle masses]; Smolyaninov JO(11)-a1005 [toy model with metamaterials]; Gerig a1406 [how to determine that other worlds exist]; Bouhmadi-López et al JCAP(19)-a1809 [and the cmb].
@ And interpretation of quantum theory: Aguirre & Tegmark PRD(11)-a1008; Nomura JHEP(11)-a1104 [eternally inflating multiverse = many worlds]; Bousso & Susskind PRD(12); Chester a1507 [and Born's Rule]; > s.a. cosmological-constant problem.
@ Interacting universes: Bertolami GRG(08); Alonso-Serrano et al PLB(13) [and the cosmological constant]; Robles-Pérez Univ(17)-a1705 [phenomenology]; Bouhmadi-López et al JCAP(19)-a1809 [and the cosmic microwave background].
@ Related topics: Gouts G&C(03)gq/02-conf [topos theoretic]; Bousso & Freivogel JHEP(07)ht/06 [paradox]; Gehrels a0707; Garriga & Vilenkin JCAP(09) [holographic description, and conformal invariance]; Rugh & Zinkernagel a1305-proc [critical note on time]; Garriga et al JCAP(13)-a1309 [non-singular bounce transitions]; Mersini-Houghton a1406-MG13 [and birth of the universe]; Marosek et al MNRAS(16)-a1509 [cyclic multiverses]; Aharonov et al FrPh(18)-a1608 [quilted multiverse]; > s.a. dark matter; Fourth Quantization; No-Cloning Theorem.

Online Resources > see Max Tegmark's page and YouTube video; Wikipedia page.

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