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InvUniv2009Ashtekar
(03 Jul 2009,
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<< Cosmo.WebHome %TOC% ---- %INCLUDE{"InvisibleUniverse2009Head"}% ---+ Abhay Ashtekar loop quantum cosmology = LQC vs WDW = Wheeler de Witt * ArXiv:0812.0177 - recommended review paper * WDW quantum cosmology not mathematically rigorous * since 1970's worry about von Neumann uniqueness theorem * LQC is rigorous * LQC solves these problems Main.BoudRoukema - 03 Jul 2009 * LQC - quantum geometry - gives repulsive force during planck epoch, i.e. a bounce * "quantum geometry resolves *all* strong singularities in homogeneous isotropic models with %$p=p(\rho)$% ... (Singh) * k=1 models bounce at 't=0', i.e. avoid singularity (Ashtekar, Pawlowski, ...) * BKL conjecture: approaching Planck era, dynamics well approximated by Bianchi I models, with Bianchi II transitions and spikes * LQC also resolves singularities in Bianchi I, II models * in LQG, there may be a general *singularity resolution theorem* * phenomenology - work in progress * super-inflation - Copeland et al * do inflation calculations using LQC-corrected Einstein eqns * horizon and flatness problems solved by super-inflation * nearly scale invariant spectrum for scalar mode * ... * evolution of perturbations from pre-BB to post-BB branch * Biswas working on this * all this is very much work in progress by LQC community * summary: * QG gives quantum bounce * physics does not end at singularities * classical GR at low curvatures/densities (Green and Unruh) * the singularities analysed here are those of direct cosmological interest (not just abstract singularities!) * phenomeology - initial results obtained, cosmologists and LQC communities working together on this
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Topic revision: r1 - 03 Jul 2009,
BoudRoukema
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