<< WebHome

main page: InvisibleUniverse2009

These are just rough notes - feel free to correct them, add links, etc. from the Invisible Universe 28 June - 3 July 2009 meeting. These are not official proceedings. The speakers might even disagree that they said anything even vaguely related to what are in these online notes! Don't say you weren't warned.

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 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
Topic revision: r1 - 03 Jul 2009, BoudRoukema
This site is powered by FoswikiCopyright © CC-BY-SA by the contributing authors. All material on this collaboration platform is copyrighted under CC-BY-SA by the contributing authors unless otherwise noted.
Ideas, requests, problems regarding Foswiki? Send feedback