Regensburg 2022 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
DY: Fachverband Dynamik und Statistische Physik
DY 3: Statistical Physics far from Thermal Equilibrium
DY 3.3: Vortrag
Montag, 5. September 2022, 10:30–10:45, H18
Mori-Zwanzig formalism for general relativity: a new approach to the averaging problem* — •Michael te Vrugt1, Sabine Hossenfelder2, and Raphael Wittkowski1 — 1Institut für Theoretische Physik, Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany — 2Frankfurt Institute for Advanced Studies, D-60438 Frankfurt am Main, Germany
Cosmology provides a coarse-grained description of the universe that is valid on very large length scales. However, the Einstein field equations are not valid for coarse-grained quantities since, due to their nonlinearity, they do not commute with an averaging procedure. Thus, it is unclear in which way small-scale inhomogeneities affect large-scale cosmology (backreaction). In this work [1], we address this problem by extending the Mori-Zwanzig projection operator formalism, a highly successful coarse-graining method from statistical mechanics, towards general relativity. This allows to derive a dynamic equation for the Hubble parameter in which backreaction is taken into account through memory and noise terms. Our results are linked to cosmological observations.
[1] M. te Vrugt, S. Hossenfelder, R. Wittkowski, Physical Review Letters 127, 231101 (2021)
*Funded by the Deutsche Forschungsgemeinschaft (DFG) – WI 4170/3-1