Quantum Gravity

The ADM and Bondi energies are key examples of observables in general relativity. They have played a crucial role to clarify the meaning of gravitational energy, and by Noether's theorem, to understand (boundary) symmetries. In spite of their conceptual importance, they are not directly measurable…

The good books on GR agree on certain aspects of the theory that we could consider to be its “core” features. Beyond the core, however, we do not know exactly what GR should allow or not allow physically. For example, should we consider spacetimes with closed causal loops as part of physical GR or…

The first part of the talk will briefly discuss the tasks that need to be accomplished in order to formulate such open quantum models in the context of quantum gravity, as well as the challenges involved. As a first step in this direction, a QFT model in the context of linearised gravity is…

Models for gravitationally induced decoherence can be formulated within the framework of open quantum systems, in which gravity is chosen as the environment and quantised together with the system under consideration. The effective dynamics of the system under the influence of the environment are…

Recent advancements in tabletop experiments may offer the first empirical proof that gravity is not classical. In the first part of my talk, I will present two effects that overcome the current limitations of Newton potential phenomenology, involving generic quantum sources of gravity. These effects…

The original spinfoam amplitude, Ponzano-Regge, has two properties in seeming contradiction: (1.) It can be written as an integral of a product of Dirac delta functions imposing that holonomies be exactly flat, and (2.) In its original sum-over-spins form, its leading order large spin asymptotics…

My presentation will introduce a new methodology to characterize properties of quantum spacetime in a strongly quantum-fluctuating regime, using tools from topological data analysis. Starting from a microscopic quantum geometry, generated nonperturbatively in terms of dynamical triangulations (DT)…

The quantization of gravity is widely believed to result in gravitons -- particles of discrete energy that form gravitational waves. But their detection has so far been considered impossible. In this talk, I will show that laboratory experiments can reveal signatures of single graviton exchange. I…

Numerical methods are powerful tools for advancing our understanding of quantum gravity. In this talk, I will introduce two complementary numerical approaches. The first focuses on solving nonlinear partial differential equations that arise in Loop Quantum Gravity (LQG)-inspired effective models…

Einstein's theory admits interesting limits with different causal structures obtained by letting the speed of light go to infinity (Galilean or "non-relativistic" limit) or to zero (Carrollian, sometimes called "ultrarelativistic", limit). The Carroll limit turns out to be relevant near spacelike…

Discrepancies between Lorentzian and Euclidean calculations of quantum corrections to de Sitter horizon thermodynamics revealed the existence of ‘edge’ degrees of freedom on the horizon. In this talk, I will review these calculations and present updates on understanding the physics of such edge…

It has been conjectured that the gravitational interaction may arise as an entropic force rather than as a result of virtual quanta exchange of a fundamental field. In this talk I will present a set of microscopic quantum models which realize this idea in detail. I will describe a simple mechanism…