Statut  Confirmé 
Série  STRLPTENSHE 
Domaines  hepth 
Date  Vendredi 4 Décembre 2020 
Heure  14:00 
Institut  LPTENS 
Salle  GoToMeeting 
Nom de l'orateur  Le Floch 
Prenom de l'orateur  Bruno 
Addresse email de l'orateur  
Institution de l'orateur  Institut Philippe Meyer 
Titre  Universal scattering laws for quiescent bouncing cosmology 
Résumé  Modifications to 3+1d general relativity (GR) at high curvatures can eliminate the Big Bang singularity in favor of a bounce. Abstracting away microscopic details of the bounce, the spacetime is simply a GR solution on both sides of a singularity hypersurface, with some theorydependent "singularity scattering map" relating the asymptotic metrics on both sides. The asymptotic metric near a singularity was studied by Belinsky, Khalatnikov and Lifshitz (BKL) and I will explain their finding that the time evolution at different points decouples. Motivated by this ultralocality property, we classify (in the absence of BKL oscillations) all singularity scattering maps that are ultralocal. By matching previous calculations on homogeneous spacetimes in f(R) gravity and in loop quantum cosmology with our classification we obtain a prediction for nonhomogeneous bounces in these theories. Lastly, we construct a class of cyclic spacetimes by solving for the collision of plane gravitational waves (which may create infinitely many successive singularities). 
Numéro de preprint arXiv  2006.08620 
Commentaires  https://global.gotomeeting.com/join/819043301 
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