Multiverse Cosmology  

Multiple Universes in General > s.a. cosmology.
* Level 1: Regions beyond our cosmic horizon (same laws and constants).
* Level 2: Other post-inflation bubbles (same laws, different constants); 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.
* Level 3: The many worlds (parallel universes) of quantum physics; > s.a. many-worlds interpretation.
* Level 4: Other mathematical structures and laws of physics.
@ I: Krauss 06 [alternate realities]; Vilenkin 06.
@ General references: Deutsch PRS(02)qp/01 [information in multiverse]; Rubin CSF(02)ap [and life]; Ellis et al MNRAS(04)ap/03; Tegmark SA(03)may, in(03)ap; Davies MPLA(04)ap [rev]; Bjorken ap/04/PRD; Stoeger et al ap/04 [philosophical]; Bettini Kairos-phy/05 [history]; Weinberg ht/05-in; McCabe gq/06 [various notions]; Davies ap/06-in [the problem of what exists]; Carr ed-07 [r pw(07)nov]; González-Díaz et al a0705 [as resolution of some problems]; Barrau CERN(07)-a0711 [intro rev]; Hall & Nomura PRD(08)-a0712 [argument in favor from unnaturalness]; Mersini-Houghton a0804, a0809-in [and initial conditions]; news sn(09)jun [Origins symposium]; Smolin pw(09)jun [criticism].
@ Level 1: Scott & Zibin IJMPD(06)ap [how many are there?]; Page a0801-in [and Christian theology].
@ 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 a0910 [inflation, number of distinguishable locally-Friedmann universes]; > s.a. brane scenarios, inflationary scenarios, wormholes [baby universes].
@ Level 3: Tegmark a0905 [objections to Everett's theory and parallel universes]
@ Anthropic reasoning: Aguirre & Tegmark JCAP(05)ht/04 [and coincidences]; Weinstein CQG(06)ht/05.
@ Cosmic natural selection, fine tuning: Smolin CQG(92), gq/94, 97; Vaas gq/02-in; 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
* 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; > s.a. probability in physics [propensity].

Other Issues > s.a. anthropic principle; variation of constants.
@ Physical constants: Gouts G&C(03)gq/02; Vilenkin PRL(95)gq/94, PRD(95)gq, gq/95-in [and quantum cosmology, inflation].
@ Predictions: Aguirre ap/05-in; Stoeger ap/06 [retroductive tests]; Page in(07)ht/06; Aguirre & Johnson PRD(08)-a0712 [bubble universes].
@ Multiverse as space of all classical universes: Gibbons & Turok PRD(08)ht/06, Vilenkin JPA(07)gq/06, JHEP(07) [measure].
@ Related topics: Gouts G&C(03)gq/02-in [topos theoretic]; Palesheva MSM(02)qp, G&C(03) [particle interference]; Bousso & Freivogel JHEP(07)ht/06 [paradox]; Gehrels a0707; Donoghue in(07)-a0710 [and particle masses]; Bertolami GRG(08) [interaction between universes].

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


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