Models of the Early Universe  

Early-Universe Variations and Pre-Big-Bang Models > s.a. entropy; kaluza-klein theory; quantum cosmology.
* Possibilities: Examples of qualitatively different predictions for the evolution of the universe are past-eternal ones (inflationary versions, steady state), bouncing or oscillating universes, and cyclic models; These can be described at either the classical or the quantum level.
* Inflation: Based on a cosmological phase transition as pre-standard model scenario.
* Ekpyrotic cosmology: Based on the brane world as pre-big bang scenario; > s.a. brane cosmology.
* Island universe: (The name is a reference to Kant's old idea) The universe is initially in a cosmological constant sea, then local quantum fluctuations violating the null energy condition create islands of matter, some of which might correspond to our observable universe.
@ Origin of the universe: Misner PR(69); Rosen AJP(87)jun; Grünbaum PhSc(89)sep, Nat(90)apr; Lévy-Leblond AJP(90)feb; Gott & Li PRD(98)ap/97, Barber gq/02 [self-creation]; news ut(12)feb [Krauss' "universe from nothing"]; > s.a. cosmology references.
@ Island universe: Dutta & Vachaspati PRD(05)ap; Piao PRD(05) [and observations]; > s.a. cosmology [future].
> Structure formation: see early-universe cosmology; inflationary phenomenology and scenarios; cosmological perturbations.

Models without Singularity > s.a. Bounces; Cyclic Models; history of relativistic cosmology; lqc models; singularities [avoidance].
* Emergent universe: A non-singular universe that starts expanding from an Einstein static universe.
* Bouncing models: Models in which the universe is expanding from a previous contracting phase, without an initial singularity; they can be classical or quantum (as in lqc); 2014, they can be considered as possible alternatives to inflation, although most models proposed so far have some problems.
@ General references: Kak phy/02 [history in India]; Garriga & Vilenkin PRD(98) [inflationary recycling]; Frampton ap/06-conf [dark energy in brane world]; Frampton 09 [I]; Lehners et al IJMPD(09)-a0910-GRF, Zhang a1102-JoC [phoenix universe]; Wetterich PDU(13)-a1303; > s.a. cosmological perturbation models; dark matter.
@ Bounces: Molina-París & Visser PLB(99)gq/98 [Tolman]; Solomons et al CQG(06)gq/01, CQG(06) [Kantowski-Sachs, Bianchi models]; Peter & Pinto-Neto PRD(02) [evidence against]; Cartier et al PRD(03)ht; Stachowiak & Szydłowski PLB(07)gq/06 [modified Friedmann equation]; Novello & Perez Bergliaffa PRP(08)-a0802 [rev]; Falciano et al PRD(08)-a0802; Lehners CQG(11)-a1106; Maier et al PRD(12)-a1111 [with a cosmological constant]; Cai et al JCAP(12)-a1206; Battefeld & Peter PRP(15)-a1406 [review]; Barrau & Linsefors JCAP(14)-a1406 [bounce from radiation, inflation and reheating]; Ferreira & Pavón EPJC(16)-a1509 [thermodynamics]; Nojiri et al PRD(16)-a1601 [in unimodular f(R) gravity]; Cheung et al a1601 [from string theory]; Peter & Vitenti MPLA(16)-a1603 [quantum FLRW, simple model]; Brandenberger & Peter FP(17)-a1603 [rev]; Ijjas & Steinhardt PRL(16)-a1606 [in Galileon theories]; Chamseddine & Mukhanov JCAP(17)-a1612 [modified gravity]; > s.a. brane-world cosmology; energy conditions; friedmann equation; higher-order gravity; hořava gravity; relativistic cosmology; scalar-tensor thories; supergravity.
@ Bounces, phenomenology: Lilley et al JCAP(11)-a1104 [observational signatures]; Xia et al PRL(14) [evidence after BICEP2?]; Li et al PRD(14)-a1403 [dark matter production]; > s.a. black-hole types [primordial]; magnetism [primordial fields]; perturbations; wormholes.
@ Cyclic / oscillating: Barrow & Dabrowski MNRAS(95); Dadhich & Raychaudhuri MPLA(99)gq; Steinhardt & Turok PRD(02)ht/01, PRD(02)ht/01, NPPS(03)ap/02 [with acceleration and recontraction]; Khoury et al PRL(04)ht/03; Brown et al JCAP(08)-ap/04 [phantom, brane-inspired]; Rendall CQG(07) [with massive scalar fields]; Clifton & Barrow PRD(07)gq [unlikely explanations of flatness]; Frampton MPLA(07)-a0705 [infinite past]; Mithani & Vilenkin JCAP(12)-a1110 [quantum-mechanically unstable], JCAP(14) [from lqc, instability]; Sahni & Toporensky PRD(12)-a1203 [and cosmological hysteresis]; Mithani & Vilenkin JCAP(15)-a1407 [stability of oscillating universes]; Cianfrani et al a1507 [from lqg]; Barrow & Ganguly a1703 [Bianchi IX with radiation and ghost field]; Barrow & Ganguly a1705-GRF [general, and mixmaster]; > s.a. cosmic strings; types of inflation.
@ Emergent universe: Ellis et al CQG(04)gq/03 [static for t → –∞]; Ellis & Maartens CQG(04); Guendelman & Labraña IJMPD(13)-a1303; Guendelman a1306-proc; Ali PLB(14)-a1310; Khodadi et al PRD(16)-a1512 [in Hořava-Lifshitz f(R) gravity].
@ Related topics: Senovilla PRL(90), PRD(96); Chinea at al PRD(92); Fakir gq/98; Wagh ap/02 [inhomogeneous]; Fernández-Jambrina GRG(05)gq [non-rotating pfluids]; Dechant et al PRD(09)-a0809, CQG(10)-a1007 [quasi-regular singularity]; Wetterich PRD(14)-a1404.

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