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VERSION:2.0
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BEGIN:VEVENT
SUMMARY:The Strong Cosmological Coincidence Problem
DTSTART:20260917T143000Z
DTEND:20260917T160000Z
DTSTAMP:20260915T171054Z
UID:8cfc0a5a-52b8-4bad-a0c4-a8a929d47698
SEQUENCE:2
CREATED:20260914T083653Z
DESCRIPTION:The standard cosmological coincidence problem asks why matter 
 and dark energy become dynamically comparable only close to the present ep
 och. I will discuss a stronger version of this problem\, motivated by the 
 observation that the growing relative importance of dark energy coincides 
 with the nonlinear development of cosmic structure.In several inhomogeneou
 s and coarse-grained descriptions\, quantities characterising structure fo
 rmation evolve in a way that resembles the effective dark energy contribut
 ion inferred within the standard cosmological model.In this context\, I wi
 ll introduce Buchert&#x27\;s scalar-averaging framework and its partitioni
 ng formalism\, which provide a natural way to separate the effects of inte
 rnal regional dynamics from the variance of expansion rates between differ
 ent regions. I will then discuss how the relativistic Zel&#x27\;dovich app
 roximation can be used to close the averaged scalar equations.I will concl
 ude by outlining how the framework of inhomogeneous cosmology may provide 
 a resolution of the strong cosmological coincidence problem.
LAST-MODIFIED:20260914T083702Z
LOCATION:DF Seminar Room (2-8.3)\, 2nd floor of Physics Building
URL:http://df.vps.tecnico.ulisboa.pt/pt/eventos/the-strong-cosmological-co
 incidence-problem/
X-ALT-DESC;FMTTYPE=text/html:<p data-block-key="soakc">The standard cosmol
 ogical coincidence problem asks why matter and dark energy become dynamica
 lly comparable only close to the present epoch. I will discuss a stronger 
 version of this problem\, motivated by the observation that the growing re
 lative importance of dark energy coincides with the nonlinear development 
 of cosmic structure.<br/></p><p data-block-key="370v8">In several inhomoge
 neous and coarse-grained descriptions\, quantities characterising structur
 e formation evolve in a way that resembles the effective dark energy contr
 ibution inferred within the standard cosmological model.<br/></p><p data-b
 lock-key="c70ts">In this context\, I will introduce Buchert&#x27\;s scalar
 -averaging framework and its partitioning formalism\, which provide a natu
 ral way to separate the effects of internal regional dynamics from the var
 iance of expansion rates between different regions. I will then discuss ho
 w the relativistic Zel&#x27\;dovich approximation can be used to close the
  averaged scalar equations.<br/></p><p data-block-key="65kca">I will concl
 ude by outlining how the framework of inhomogeneous cosmology may provide 
 a resolution of the strong cosmological coincidence problem.</p>
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