Inflationary Universe |
In General > s.a. inflationary phenomenology
and scenarios; inflation and planck-scale physics.
* Idea: A universe with an accelerating expansion rate,
d2a/dt2 > 0
for FLRW spacetime in proper time; The expansion may be exponential, a ∝ exp{Ht}.
* Origin in homogeneous cosmology:
It arises in models where (e.g., because of a phase transition) the energy density
remains constant during the expansion, like a cosmological constant; This changes
drastically the expansion rate with respect to the standard big-bang model, and
makes it exponential in time (inflation), and we get a de Sitter-like behavior.
* Motivation: A sufficiently long
inflation could solve the horizon, flatness and monopole problems of big bang
models, and possibly explain structure formation; It makes predictions, and
provides a link between high-energy physics and cosmology.
* Generalized view: The universe
has no beginning and no end, inflating bubbles in it keep producing new ones.
* 1980s: Inflation predicts
Ω = 1, but observationally we see Ω < 0.3 (without dark matter).
* 1991: What is the inflaton?
How does it become ordinary matter (reheating problem)?
* 1998: Chaotic inflation seems
to be the most widely accepted; Requires the least amount of fine tuning.
* 2008: Predictions from inflation
have so far been confirmed, but what drove it and how long did it last?
* 2013: The single field slow-roll
inflationary scenarios (with minimal kinetic term) are favored, based on Planck
satellite data.
* 2014: BICEP2 Collaboration results
on the ratio of power in tensor to scalar density perturbations are seen as
confirming inflation.
Specific Issues > s.a. de sitter-cft;
Effective Field Theory; holography
in field theory; civilizations; singularities [theorems];
arrow of time.
* Issues: Open questions are understanding
whether the universe needed to be in a very smooth initial state for inflation; the quantum
theory of cosmological perturbations; how these might have led to inflation; and what
imprint they left on the resulting classical spacetime.
@ General references:
Albrecht et al PRD(87);
Goncharov & Linde JETP(87);
Jensen & Stein-Schabes PRD(87);
Ellis CQG(88) [with current Ω ≠ 1];
Accetta & Steinhardt GRG(91);
Frolov & Kofman JCAP(03)ht/02 [de Sitter thermodynamics];
Kinney & Riotto JCAP(06)ap/05 [uncertainties].
@ Preheating and reheating: Dolgov & Linde, Abbott et al [elementary theory];
Boyanovsky et al ap/96-proc [review];
Kofman et al PRD(97)hp;
Bassett & Tamburini PRL(98) [in GUTs];
Brandenberger hp/01-proc;
Allahverdi et al ARNPS(10)-a1001.
@ And phase transitions:
Mazenko et al PRD(85);
Freivogel et al JCAP(09)-a0901 [probability distribution for bubble collisions];
Johnson et al PRD(12)-a1112 [outcome of bubble collisions];
McEwen et al a1206-proc [bubble-collision signatures in the cmb];
Pashitskii & Pentegov JETP(16)-a1510 [driven by changing scalar curvature];
Pekker & Shneider a2102 [physical processes in the transition region];
> s.a. multiverse [bubbles as universes].
@ Inhomogeneities, causality / genericity:
Goldwirth & Piran PRD(89),
PRP(92);
Calzetta & Sakellariadou PRD(92),
PRD(93);
Iguchi & Ishihara PRD(97),
et al PRD(97)gq/96 [curvature];
Kaloper et al PRD(99)ht/98;
Vachaspati & Trodden PRD(00)gq/98;
Toporensky G&C(99)gq;
Sakai CQG(04)gq/03 [topological inflation];
Imponente & Montani gq/04;
Carroll & Tam a1008 [and invariant measure on solutions];
Corichi & Karami PRD(11)-a1011 [the measure problem and lqc];
Greene et al PLB(11) [smooth early universe from weak gravity];
Perez & Pinto-Neto G&C(11)-a1205;
Corichi & Sloan CQG(14)-a1310
[Hamiltonian dynamics, attractor solutions and the measure problem];
Easther et al JCAP(14)-a1406 [multifield];
East et al JCAP(16)-a1511;
Clough et al a1608 [robustness];
Azhar a1911 [effective field theory approach];
> s.a. inflationary phenomenology [perturbations].
@ Initial conditions: Calzetta PRD(91);
Kaloper et al JHEP(02)ht;
Collins & Holman ht/05 [effective theory renormalization];
Handley et al PRD(14)-a1401;
Carrasco et al PRD(15)-a1506 [and cosmological attractors];
Brandenberger IJMPD(17)-a1601 [rev];
Dimopoulos & Artymowski APP(17)-a1610;
Linde a1710-conf [rev];
Mishra et al PRD(18)-a1801 [in a FLRW universe];
Finn & Karamitsos PRD(19)-a1812 [finite measure];
Sloan & Ellis PRD(19)-a1810 [Higgs as dilaton].
@ Likelihood of inflation: Albrecht & Sorbo PRD(04)ht [framework];
Miao & Woodard JCAP(15)-a1506 [fine tuning].
References
> s.a. entropy bounds; gravitational instantons;
history; cosmological models [alternatives to inflation].
@ I: Guth & Steinhardt SA(84)may;
Lindley Nat(90)may;
Steinhardt Nat(90)may;
Linde SA(94)nov;
Lidsey 00;
Steinhardt SA(11)apr [issues].
@ II: Huggins TPT(13) [and vacuum energy].
@ Books: Abbott & Pi 86;
in Kolb & Turner 94;
Linde 90-ht/05;
Guth 97;
Liddle & Lyth 00;
Lemoine et al 08;
Lyth & Liddle 09;
Gorbunov & Rubakov 10 [and perturbations].
@ Reviews: Linde RPP(84),
PT(87)sep,
gq/96-conf,
gq/96-conf;
Turner APPB(87),
in(88);
Olive PRP(90);
Brandenberger ap/96,
ap/97,
hp/99-ln;
Starobinsky ap/98-conf;
Peebles ap/99-proc;
Guth PRP(00)ap,
ap/00-proc,
ap/01-proc;
Lyth hp/00;
Brandenberger hp/01-proc,
ap/02;
Linde IJMPA(02)ht/01-proc [vs ekpyrotic];
García-Bellido NPPS(03)hp/02;
Turok CQG(02);
Turner AHP(03)ap/02-proc;
King Pra(04)hp/03-conf;
Guth ap/03-in,
ap/04-in;
Linde PS(05)ht/04-conf;
Guth & Kaiser Sci(05)ap;
Bassett et al RMP(06)ap/05 [especially reheating];
Guth JPA(07)ht-conf [especially eternal];
Linde LNP(08)-a0705-conf;
Kinney IJMPA(07);
Baumann & Peiris ASL(09)-a0810;
Sriramkumar a0904-CS [and perturbations];
Baumann a0907-ln [TASI lectures];
Linde a1402-ln [after Planck 2013];
Clesse a1501-proc,
Martin a1502-ln [after Planck 2015];
Rangarajan a1506-conf [after Planck and BICEP2];
Martin a1807-proc,
a1902-in [status].
@ Intros: Liddle ap/99-proc;
Faraoni AJP(01)mar-phy/00;
Albrecht ap/00-ln;
Watson ap/00;
Tsujikawa hp/03-ln;
Lazarides JPCS(06)hp;
Langlois a0811-conf;
Kinney a0902-ln;
Enqvist a1201-ln;
Senatore a1609-ln;
Vázquez et al a1810-ln.
@ Conceptual: Earman & Mosterin PhSc(99)mar;
Knobe et al BJPS(06)phy/03 [implications, and doomsday];
García-Bellido a1003-wd [epistemological foundations];
Ijjas et al PLB(14)-a1402 [alternative inflationary paradigm after Planck2013];
Horgan blog(14)dec [Paul Steinhardt's position];
Singal a1603-conf [questioning the motivation].
@ Issues: Hawking et al PRD(01)ht/00 [and trace anomaly];
Ijjas et al PLB(13)
and response Guth et al PLB(14),
SA(17)
and rebuttal SA(17) [need or new ideas];
> s.a. Boltzmann Brains; chaos
in general relativity; energy conditions; tachyons.
Scientific ideas should be simple, explanatory, predictive. The inflationary multiverse as
currently understood appears to have none of those properties. – Paul Steinhardt, 2014.
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send feedback and suggestions to bombelli at olemiss.edu – modified 5 feb 2021