Quantum Gravity and Emergent Cosmology: A Group Field Theory Perspective

This seminar is the second part of a two-part mini-seminar series organized by the Quantum Gravity Gatherings study group.

It is intended to have a more lecture-style format, with an extended duration of up to two hours.
This will allow the speaker sufficient time to introduce the framework in a clear and pedagogical manner, while also leaving ample room for questions and discussion with the audience.

Title:
Quantum Gravity and Emergent Cosmology: A Group Field Theory Perspective

Abstract:
I will introduce the Group Field Theory (GFT) approach to quantum gravity, emphasizing its connections with matrix and tensor models, discrete gravity path integrals, and loop quantum gravity. Through these connections, GFTs emerge naturally as quantum field theories of "spacetime atoms".

I will then discuss how semiclassical, macroscopic physics can emerge from GFT, touching upon the challenges of defining locality and coarse-graining in quantum gravity, and on how these can be naturally addressed within relational frameworks. I will present a concrete implementation of this relational strategy in GFT and show how a simple relational coarse-graining scheme can be used to extract cosmological physics.

Within the resulting cosmological models, the initial singularity is resolved into a quantum bounce, while cosmological perturbations emerge from the quantum entanglement of the underlying quantum-gravity degrees of freedom, with effective dynamics modified on trans-Planckian scales. Finally, I will show that quantum-gravitational interactions alone can generate cosmic acceleration, leading both to dynamical dark energy and to a slow-roll inflationary phase. I will conclude by showing recent observational constraints on such emergent dynamical dark energy models, and by providing an outlook on future research directions.