On quantum gravity, Asymptotic Safety, and paramagnetic dominance

TL;DR

This paper explores the Asymptotic Safety approach to quantum gravity, revealing that a nontrivial ultraviolet fixed point arises due to paramagnetic interactions dominating diamagnetic ones, akin to magnetic systems.

Contribution

It uncovers the physical mechanism behind the fixed point in quantum gravity using an analogy to magnetic systems, highlighting the dominance of paramagnetic interactions.

Findings

Ultraviolet fixed point predicted by functional renormalization group studies.

Spacetimes in Quantum Einstein Gravity exhibit a paramagnetic response.

Similarities between quantum gravity vacuum and Yang-Mills theory vacuum.

Abstract

We discuss the conceptual ideas underlying the Asymptotic Safety approach to the nonperturbative renormalization of gravity. By now numerous functional renormalization group studies predict the existence of a suitable nontrivial ultraviolet fixed point. We use an analogy to elementary magnetic systems to uncover the physical mechanism behind the emergence of this fixed point. It is seen to result from the dominance of certain paramagnetic-type interactions over diamagnetic ones. Furthermore, the spacetimes of Quantum Einstein Gravity behave like a polarizable medium with a "paramagnetic" response to external perturbations. Similarities with the vacuum state of Yang-Mills theory are pointed out.