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SUMMARY:Kostas Tzanavaris (MPI Hannover and Leibniz Universitaet Hannover)
DTSTART:20260623T090000Z
DTEND:20260623T100000Z
DTSTAMP:20260623T012339Z
UID:NKUA-HEP/59
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/NKUA-HEP/59/
 ">The Free Boundary Problem in GR</a>\nby Kostas Tzanavaris (MPI Hannover 
 and Leibniz Universitaet Hannover) as part of NKUA HEP Seminars\n\n\nAbstr
 act\nA significant problem in physics and cosmology is the problem of init
 ial/boundary conditions. This is both technical\, as the boundary in these
  situations is typically a spacelike singularity (the Big Bang) and concep
 tual\, as there is no clear way of choosing a set of initial condition wit
 hout bias.\n\nIn this talk\, I will present a general method for deducing 
 initial conditions at the Big Bang\, by treating the initial singularity a
 s a free variational boundary. The resulting boundary conditions rule out 
 Kasner-like geometries as well as BKL solutions\, while favouring conforma
 lly regular geometries. In the case of linear perturbations around FLRW\, 
 the boundary conditions are equivalent to conformal regularity\, in agreem
 ent with large-scale cosmological observations.\n
LOCATION:https://researchseminars.org/talk/NKUA-HEP/59/
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