BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:A novel approach to cosmological observables: the observer 3-cylin
 der formalism - Ermis Mitsou (University of Zurich)
DTSTART:20171030T130000Z
DTEND:20171030T140000Z
UID:TALK81441@talks.cam.ac.uk
CONTACT:Tobias Baldauf
DESCRIPTION:I will discuss ongoing work on a new formalism for the rigorou
 s computation of cosmological observables\, which is important in the era 
 of precision cosmology. The conceptual key is that what we measure are the
  components of the photon momentum vector and polarization tensor with res
 pect to an orthonormal basis privileged by the observer\, i.e. a tetrad. W
 orking exclusively in such a basis all over space-time (the tetrad formali
 sm of GR) leads to explicitly coordinate-independent expressions where the
  involved quantities are the ones that are actually being measured. Most i
 mportantly\, it also allows one to parametrize these quantities on the pas
 t light-cone by using the fundamental observables that are the redshift an
 d observed angles\, thus leading to the relations that are actually constr
 ained by observations. After discussing the required geometrical framework
  ("observer 3-cylinder")\, which is constructed at the fully non-linear ba
 ckground-independent level\, I will illustrate its features by focusing on
  the case of weak lensing observables.
LOCATION:CMS\, Pav. B\, CTC Common Room (B1.19) [Potter Room]
END:VEVENT
END:VCALENDAR