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UID:108@gravity.physik.fau.de
DTSTART;TZID=Europe/Berlin:20241217T160000
DTEND;TZID=Europe/Berlin:20241217T170000
DTSTAMP:20241208T145519Z
URL:https://www.gravity.physik.fau.de/events/bounce-versus-long-squeeze-on
 -two-different-outcomes-of-quantum-gravitational-collapse-zoom-michal-bobu
 la-university-of-wroclaw/
SUMMARY:Bounce versus long squeeze: on two different outcomes of quantum gr
 avitational collapse (Zoom)\, Michal Bobula (University of Wroclaw)
DESCRIPTION:I will discuss aspects of two models of dust collapse in effect
 ive quantum gravity. The first is the Husain-Kelly-Santacruz-(Wilson-Ewing
 ) dust collapse model in effective loop quantum gravity. The model of cons
 ideration is a special case of the Giesel-Liu-Singh-Weigl framework for po
 lymerized Lemaitre-Tolman-Bondi spacetimes. I will focus on rigorous causa
 l structure analysis\, in particular\, I will present numerically computed
  Penrose-Carter diagrams for both homogeneous Oppenheimer-Snyder collapse 
 scenario and nonhomogeneous one with a Gaussian initial dust profile.  In
  the nonhomogeneous variant\, the results for a considerable portion of sp
 acetime will no longer be reliable due to the presence of so-called shell-
 crossing singularities\, however\, the problem of (non)-existence of the t
 imelike singularity known from the homogeneous scenario will remain open. 
 In the second part of my talk\, I will discuss a modified model of a homog
 eneous Oppenheimer-Snyder collapse scenario where the exterior of the coll
 apsing dust ball is a Hayward black hole spacetime and the interior is a d
 ust Friedmann-Robertson-Walker cosmology. This interior cosmology will be 
 entirely determined by the junction conditions with the exterior black hol
 e. It turns out to be non-singular\, displaying a power-law contraction wh
 ich precedes a de Sitter phase (long squeeze) or\, reversely\, a power-law
  expansion followed by a de Sitter era. We will learn that cosmic inflati
 on\, in the time-reversed setting\, is a (quantum) mechanism that decelera
 tes the collapsing matter and prevents it from singularity formation.\n
CATEGORIES:Group Seminar
LOCATION:SR 02.729 + Zoom\, Staudtstraße 7 / B2\, Erlangen\, 91058\, Germa
 ny
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=Staudtstraße 7 / B2\, Erla
 ngen\, 91058\, Germany;X-APPLE-RADIUS=100;X-TITLE=SR 02.729 + Zoom:geo:0,0
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TZID:Europe/Berlin
X-LIC-LOCATION:Europe/Berlin
BEGIN:STANDARD
DTSTART:20241027T020000
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
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