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SUMMARY:Cosmology from the boundary - Paolo Benincasa (Niels Bohr) 
DTSTART:20190506T120000Z
DTEND:20190506T130000Z
UID:TALK121360@talks.cam.ac.uk
CONTACT:Sadra Jazayeri
DESCRIPTION:Our understanding of physical phenomena is intimately linked t
 o the way we understand the relevant observables describing them. While a 
 big deal of progress has been made for processes occurring in flat space-t
 ime\, much less is known in cosmological settings\, where it is still uncl
 ear how to isolate fundamental physics from the relevant observables: we d
 o not know how to answer the question "what are the conditions they ought 
 to satisfy in order to come from a consistent evolution in cosmological sp
 ace-times?". In this talk I will illustrate the path my collaborators and 
 I have recently undertaken in order to address such a question\, aiming to
 wards the idea of a formulation of cosmology "without time". \n\nThe focus
  of the discussion will be the late-time wavefunction of the universe for 
 a large class of scalar toy models and its properties in perturbation theo
 ry. I will discuss its singularity structure and how it satisfies a recurs
 ion relation\, which allows to compute it directly in terms of "boundary" 
 data. Amazingly enough\, a new mathematical structure\, we called "cosmolo
 gical polytopes"\, which has its own first principle definition\, encodes 
 the singularity structure we ascribe to the perturbative wavefunction of t
 he universe\, and makes explicit its relation to the flat-space S-matrix. 
 After a gentle introduction to the cosmological polytopes\, I will stress 
 how they allow us to: compute the wavefunction of the universe at arbitrar
 y points and arbitrary loops (with novel representations for it)\; interpr
 et the residues of its poles in terms of flat-space processes\; provide a 
  general geometrical proof for the flat-space cutting rules\; reconstruct 
 the perturbative wavefunction from the knowledge of the flat-space S-matri
 x and a subset of symmetries enjoyed by the wavefunction.
LOCATION:CMS\, Pav. B\, CTC Common Room (B1.19) [Potter Room]
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