CDT: Universes on a computer

by Dr Dániel Németh (Jagiellonian University Kraków)

Thursday 3 Feb 2022, 14:30 → 16:30 Europe/Rome

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Causal Dynamical Triangulations (CDT) is a nonperturbative
approach to quantum gravity. The triangulation in the name refers to
Regge's method to discuss gravity, and Feynman's path integral method
allows one to study the quantum behavior of this model. With the help of
numerical simulations, we create Universes, where the dynamics are
governed by the discretized Einstein-Hilbert action, and each different
triangulation counts as a different path in the path integral. Even
though nothing is placed in by hand, the model has a very rich phase
diagram, where each phase represents a significantly different structure
of spacetime. One of these phases is the so-called deSItter phase, where
the (EMERGENT) Universe has semiclassical properties and the effective
action agrees with the Hartle-Hawking minisupersapce model. In the past
years, the properties of the empty CDT universes were thoroughly
analyzed, and recently we managed to add classical and quantum scalar
fields to the model. In my presentation, I will introduce the audience
to the field of CDT and talk about the state of the art.