SPS Journal Club: “The Gravitational Path Integral and Initial Conditions of the Universe” by Luis Zapata

Strings, Pheno and the Swampland (SPS) Journal Club. Every Thursday at 12:00 in the Red Room.

Venue&Time: Red Room / 12:00

Speaker: Luis Zapata

Title: “The Gravitational Path Integral and Initial Conditions of the Universe”

Abstract: Tracing the cosmic evolution of the universe backward leads to a regime where any classical and effective description of spacetime and matter is expected to break down. Understanding those initial conditions raises the question whether a UV complete theory of Quantum Gravity can provide a consistent framework describing its initial stages. Despite the significant progress in UV-complete approaches such as String Theory, a fully satisfactory answer accounting for these cosmological initial conditions remains open.

In this talk, we will explore a bottom-up approach to this question through the Hartle-Hawking no-boundary proposal introduced in the 1980s. This proposal attempts to define the initial quantum state of the universe through a gravitational path integral over geometries satisfying suitable boundary conditions. We will review the basic ideas, placing particular emphasis on implications for inflationary initial conditions of our universe.