Speaker
Description
I report on recent progress in the computation of gauge-invariant relational observables around highly symmetric backgrounds, to arbitrary orders in perturbative quantum gravity and without introducing extra fields which change the dynamics. I then explain how one can compute quantum gravitational corrections to the Hubble rate (the local expansion rate of the universe) and the Newtonian gravitational potential of a point particle using these observables. For the Hubble rate, the one-loop result confirms the physical picture of the mutual attraction of low-energy gravitons which are created during inflation. The result for the Newtonian potential consist of two parts: the first stems from graviton loops and agrees with the correction derived by other methods, while the second one is sourced by the quantum fluctuations of the particle's position and energy-momentum, and may be viewed as an analog of a "Zitterbewegung". Based on arXiv:2303.16218, arXiv:2109.09753, arXiv:1806.11124 and references therein.
