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SUMMARY:Timescape versus ΛCDM — precision tests of emerging spatial cur
 vature
DTSTART;VALUE=DATE-TIME:20260917T100500Z
DTEND;VALUE=DATE-TIME:20260917T103000Z
DTSTAMP;VALUE=DATE-TIME:20261027T175531Z
UID:indico-contribution-31306@indico.ific.uv.es
DESCRIPTION:Speakers: David Wiltshire ()\nThe timescape cosmology returns 
 to first principles\, to explain apparent cosmic acceleration in the stati
 stical regime of general relativity. As inhomogeneities in density and exp
 ansion grow\, they back react on the average cosmic expansion\, which diff
 ers from conventional FLRW models. Crucially\, dynamical spatial curvature
  arises as time-varying gradients of the kinetic energy of expansion\, dep
 ending directly on the volume fraction of cosmic voids.\n\nThe timescape e
 xpansion history is close to ΛCDM\, but with differences at a precision w
 hich we are now finally probing. Whereas ΛCDM is increasingly challenged\
 , independent observational tests now favour timescape. In particular\, th
 e recent DESI evidence for "evolving dark energy" gives a dark energy "equ
 ation of state" w(z) consistent with timescape's non-FLRW evolution\, as p
 redicted in 2009. Projections made in 2014 for the Euclid mission showed t
 hat Euclid will distinguish FLRW expansion histories from those with emerg
 ing spatial curvature\, including timescape\, by the definitive Clarkson-B
 assett-Lu (CBL) test. The CBL test consists of two parts: the first part r
 equiring over 1000 precise type Ia supernova luminosity distance measureme
 nts was completed in our recent analysis of the Pantheon+ data\, finding v
 ery strong Bayesian evidence (ln B > 5) in favour of timescape over ΛCDM.
  Furthermore\, even restricting the sample to redshifts beyond any convent
 ional scale of statistical homogeneity\, z > 0.075\, timescape is preferre
 d over ΛCDM with ln B > 1. This was confirmed independently by the DES su
 rvey.\n\nThe second part of the CBL test involving Euclid BAOs over a reds
 hift range\, 0.7 \n\nhttps://indico.ific.uv.es/event/8160/contributions/31
 306/
LOCATION:
URL:https://indico.ific.uv.es/event/8160/contributions/31306/
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