Quantum fluctuations in the effective relational GFT cosmology

TL;DR

This paper investigates quantum fluctuations of geometric observables in GFT cosmology, analyzing their evolution during different universe phases, including near the quantum bounce, to understand the quantum nature of early universe dynamics.

Contribution

It provides a detailed analysis of quantum fluctuations in GFT cosmology, especially near the quantum bounce, and tests the relational evolution framework using matter clock observables.

Findings

Quantum fluctuations remain controlled during late-time evolution.

Significant quantum effects are observed near the quantum bounce.

Relational evolution remains valid in the analyzed regimes.

Abstract

We analyze the size and evolution of quantum fluctuations of cosmologically relevant geometric observables, in the context of the effective relational cosmological dynamics of GFT models of quantum gravity. We consider the fluctuations of the matter clock observables, to test the validity of the relational evolution picture itself. Next, we compute quantum fluctuations of the universe volume and of other operators characterizing its evolution (number operator for the fundamental GFT quanta, effective Hamiltonian and scalar field momentum). In particular, we focus on the late (clock) time regime, where the dynamics is compatible with a flat FRW universe, and on the very early phase near the quantum bounce produced by the fundamental quantum gravity dynamics.