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SUMMARY:Can we test cosmic homogeneity and isotropy? - Jenny Wagner (Baham
 as Advanced Study Institute &amp\; Conferences)
DTSTART:20230505T120000Z
DTEND:20230505T130000Z
UID:TALK200527@talks.cam.ac.uk
CONTACT:Isobel Romero-Shaw
DESCRIPTION:The Cosmological Principle (CP) was a major achievement of mod
 ern \ncosmology to turn qualitative statements into quantitative ones. It 
 \nmakes the strong assumption that space is globally homogeneous and \niso
 tropic. By doing so\, it reduces Einstein’s Field Equations to provide \
 nhighly symmetric cosmological models. The latter then enable us to \ninte
 rpret a very sparse amount of data and put them into a common \ncosmologic
 al context. Consequently\, cosmologists could probe large-scale \nproperti
 es of the known universe starting in the 1920s. Observational \ntechniques
  greatly advanced over the last century and provided myriads \nof data wit
 h increasing quality. So\, what started as “all places in the \nuniverse
  are alike” – a vague but well-working formulation back then – \nnow
  faces a semantic debate how to define “isotropy” and “homogeneity
 ” \nin the era of statistical\, data-driven inferences. Given the increa
 sed \namount of observations\, we may ask whether the model-driven approac
 h of \nusing the CP as an a priori assumption is still adequate or can be 
 \nabandoned in favour of a data-based approach.\n\nWithin this setting\, I
  will give a review on the current status of the \nusage and the validity 
 of the CP in recent cosmic data evaluations based \non our community white
  paper Aluri et al. Class.Quant.Grav. 40 (2023) 9\, \n094001\, which joint
 ly discusses several tensions that challenge not only \nour cosmological c
 oncordance model but the entire class of homogeneous \nand isotropic cosmo
 logies.\n\nOur paper (Aluri et al. 2023):\nhttps://doi.org/10.1088/1361-63
 82/acbefc\n\nOur communities:\nhttps://cosmoprinciple.wordpress.com and ht
 tps://cosmoversetensions.eu
LOCATION:Potter room/Zoom
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