Cosmological time evolution without time

June 4, 2018
3:00pm to 4:00pm

IFT Seminar Room/Red Room

Theoretical Physics, general interest
Paolo Benincasa
Niels Bohr Institute

IFT Seminar Room/Red Room


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
space-time, 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 late-time wavefunction of the universe, from which the (more
traditionally studied) late-time correlators can be read off. Questions
such as "what properties these quantities need to satisfy in order to
come from a consistent time evolution in cosmological space-times?", 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". I will discuss a very first step in this
direction, describing new representations for the (way too mystified)
wavefunction of the universe in terms of just "boundary data" as well as
their physical content, its striking relation to the flat-space S-matrix
and to the late-time correlators. Amazingly enough, all this information
is encoded in new mathematical structures, which I will provide a gentle
introduction to.