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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:3
UID:UW-Physics-Event-7050
DTSTART:20221104T203000Z
DTEND:20221104T213000Z
DTSTAMP:20260414T152654Z
LAST-MODIFIED:20221028T140803Z
LOCATION:2241 Chamberlin Hall
SUMMARY:How do we know what we know? The importance of absolute anchor
 s in cosmology\, Physics Department Colloquium\, Francis-Yan Cyr-Racin
 e\, University of New Mexico
DESCRIPTION:Since they naturally live in angular and redshift space\, 
 astronomical observations have a built-in invariance under rescaling a
 ll length scales in the problem. Breaking this invariance requires the
  use of anchors\, such as known distances or energy scales\, that can 
 set the absolute scale of the problem. These anchors are fundamental t
 o our knowledge of cosmological distances throughout the Universe\, an
 d provide the backbone on which much of our knowledge of cosmology res
 ts. These pillars have recently come under renewed scrutiny due to app
 arently discrepant measurements of the Hubble constant\, a very import
 ant cosmological quantity which sets the size and age of the observabl
 e Universe.  Here\, we carefully examine the key anchors underpinning 
 observations of the cosmic microwave background and baryon acoustic os
 cillations\, finding ways to detach these measurements from their trad
 itional anchors and fully restore their intrinsic scaling invariance. 
 Not only can this help to understand the possible cause of the Hubble 
 constant discrepancy\, but it also sheds new light on the origins of c
 osmological constraints on new physics beyond the Standard Model. This
  in turn provides us with a general toolbox to design novel cosmologic
 al models that are automatically compatible with observations. The les
 sons we draw here about fundamental measurement anchors have broad app
 lications outside of cosmology and astrophysics.   
URL:https://www.physics.wisc.edu/events/?id=7050
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