Quantum Gravity 2020

This talk will provide an overview of current approaches to quantum gravity, with their respective merits and open problems (`comparative quantum gravity'). To this aim I will focus on some key issues that must be addressed by all approaches

I will summarise the main achievements of loop quantum gravity and provide my view on the issues that I consider of central importance for present and future efforts.

Gravity is unique among the other forces in that within general relativity we are able to do calculations which, when properly interpreted, give us information about non-perturbative quantum gravity. A classic example is Bekenstein and Hawking's calculation of the entropy of a black hole, and a more…

I will review some developments in horizon thermodynamics from the past few years, highlighting especially the distinct notions of entropy that seem to apply to dynamically evolving black holes, and their extension from classical to semiclassical gravity.

This talk will feature a brief introduction to the gravitational asymptotic safety program before reviewing the current status of the field. Motivated by recent developments, I will introduce the form factor formulation of the quantum effective action and explain how various quantum gravity programs…

It has taken several decades of exploring statistical models of quantum gravity (aka nonperturbative gravitational path integrals) to understand how diffeomorphism-invariance, unitarity and the presence of a causal structure can be simultaneously accounted for in a lattice gravity framework. Causal…

I will begin with a short review of causal set theory (CST) focusing on the features that distinguish it from other approaches to quantum gravity. Most striking is a characteristic non-locality due to the Lorentz non-violating Poisson-discreteness in the continuum approximation. The discrete causal…

Analogue gravity summarises an effort to mimic physical processes that occur in the interplay between general relativity and field theory in a controlled laboratory environment. The aim is to provide insights in phenomena that would otherwise elude observation: when gravitational interactions are…

The study of scattering amplitudes has uncovered extraordinary dualities linking real-world particles such as gravitons, gluons, and pions. We discuss how these developments have been amalgamated with classic tools from effective field theory to derive new results relevant to the search for…

A quantum theory of gravity is expected to be described by a Hilbert space endowed with additional mathematical structure appropriate for describing gravitational physics. I discuss aspects of this structure that can be inferred perturbatively, along with connections to arguments for holography and…