Samhällsvetenskapliga fakulteten

Seminarium: Cosmological Polytopes and the Wavefunction of the Universe

  • Datum:
  • Plats: A73121
  • Föreläsare: Paolo Benincasa (NBI)
  • Kontaktperson: Fabrizio Nieri
  • Seminarium

In this talk I will present a novel approach to understanding cosmological observables, such as the wavefunction of the universe and the late-time correlators. The general questions we ask are: Which features should these observables have to come from a consistent unitary evolution in cosmological space-time? If someone hands them to us, how do we check that they are correct? Concretely, I will focus on the wavefunction of the universe for a class toy models of scalars with time-dependent coupling constants, including conformally coupled scalars (with non-conformal interactions) in  FRW  cosmologies as a special case. Each Feynman diagram turns out to be associated with an universal rational integrand, which in turn can be identified as a canonical form of a new polytope, the cosmological polytope. Strikingly, these objects have a first principle definition, which does not refer to physics. Beautifully, the cosmological polytope geometrizes the singularity structure of the wavefunction,which is a universal feature of all the theories. Different representations for the wavefunction of the universe can be obtained as different triangulations of the cosmological polytope: This feature allow to find new representations, some of them with no current physical interpretation. Finally, I will comment on the relation between the wavefunction of the universe, the cosmological polytope and the flat-space S-matrix, and how these two observables are related to one another.