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SUMMARY:Prof. Istvan Szapudi on "A Concordance Cosmology without Dark Ener
gy"
DTSTART;VALUE=DATE-TIME:20170428T013000Z
DTEND;VALUE=DATE-TIME:20170428T023000Z
DTSTAMP;VALUE=DATE-TIME:20170625T033524Z
UID:indico-event-1137@cern.ch
DESCRIPTION:According to the separate universe conjecture\, spherically sy
mmetric sub-regions in an isotropic universe behave like mini-universes wi
th their own cosmological parameters. This is an excellent approximation i
n both Newtonian and general relativistic theories. We estimate local expa
nsion rates for a large number of such regions\, and use the volume-averag
ed increment of the scale parameter at each time step in an otherwise stan
dard cosmological N-body simulation. The particle mass\, corresponding to
a coarse graining scale\, is an adjustable parameter. This mean field appr
oximation neglects tidal forces and boundary effects\, but it is the first
step towards a non-perturbative statistical estimation of the effect of n
on-linear evolution on the expansion rate\, often associated with backreac
tion. Using our algorithm\, a volume- averaged simulation with the Ωm = 1
Einstein–de Sitter setting in each region closely tracks the expansion
and structure growth history of a ΛCDM cosmology\, and we confirm the num
erical results with analytic calculations as well. The approximately share
d expansion history guarantees consistency with the concordance model and\
, due to small but characteristic differences\, our model can be distingui
shed from the standard ΛCDM model by future precision observations. Furth
ermore\, our model naturally resolves the emerging tension between the loc
al Hubble constant and the Planck best-fitting cosmology.\n\nhttp://indico
.phys.hawaii.edu/conferenceDisplay.py?confId=1137
LOCATION:Watanabe Hall 112
URL:http://indico.phys.hawaii.edu/conferenceDisplay.py?confId=1137
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