Statut  Confirmé 
Série  RENCTHEO 
Domaines  hepth 
Date  Jeudi 10 Janvier 2019 
Heure  10:00 
Institut  IHP 
Salle  201 
Nom de l'orateur  Benincasa 
Prenom de l'orateur  Paolo 
Addresse email de l'orateur  
Institution de l'orateur  Niels Bohr Institute 
Titre  Cosmology from the boundary 
Résumé  Our understanding of physical phenomena is intimately linked to the way we understand the relevant observables describing them. While a big deal of progress has been made for processes occurring in flat spacetime, much less is known in cosmological settings. In this context, we have processes which happened in the past and which we can detect the remnants of at present time. Thus, the relevant observable is the latetime wavefunction of the universe. Questions such as "what properties they ought to satisfy in order to come from a consistent time evolution in cosmological spacetimes?", are still unanswered, and are compelling given that in these quantities time is effectively integrated out. In this talk I will report on some recent progress in this direction, aiming towards the idea of a formulation of cosmology "without time". Amazingly enough, a new mathematical structure, we called "cosmological polytope", which has its own first principle definition, encodes the singularity structure we ascribe to the perturbative wavefunction of the universe, and makes explicit its (surprising) relation to the flatspace Smatrix. I will stress how the cosmological polytopes allow us to: compute the wavefunction of the universe at arbitrary points and arbitrary loops (with novel representations for it); interpret the residues of its poles in terms of flatspace processes; provide a general geometrical proof for the flatspace cutting rules; reconstruct the perturbative wavefunction from the knowledge of the flatspace Smatrix and a subset of symmetries enjoyed by the wavefunction. 
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