AUTHOR=Pawlowski Jan M. , Reichert Manuel 

TITLE=Quantum Gravity: A Fluctuating Point of View

JOURNAL=Frontiers in Physics

VOLUME=Volume 8 - 2020

YEAR=2021

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2020.551848

DOI=10.3389/fphy.2020.551848

ISSN=2296-424X

ABSTRACT=In this contribution, we discuss the asymptotic safety scenario for quantum gravity with a functional renormalisation group approach that disentangles dynamical metric fluctuations from the background metric. We review the state of the art in pure gravity and general gravity-matter systems. This includes the discussion of results on the existence and properties of the asymptotically safe ultraviolet fixed point, full ultraviolet-infrared trajectories with classical gravity in the infrared, and the curvature dependence of couplings also in gravity-matter systems. The results in gravity-matter systems concern the ultraviolet stability of the fixed point and the dominance of gravity fluctuations in minimally coupled gravity-matter systems. Furthermore, we discuss important physics properties such as locality of the theory, diffeomorphism invariance, background independence, unitarity, and access to observables, as well as open challenges.