%0 Generic
%A Düll, Maximilian
%C Heidelberg
%D 2020
%F heidok:28630
%R 10.11588/heidok.00028630
%T Gravitational closure of matter field equations  General theory & symmetrization
%U https://archiv.ub.uni-heidelberg.de/volltextserver/28630/
%X Already Einstein used insights from Maxwell theory in order to develop the theory of relativity. This connection between matter and gravity theories is a lot deeper than it first seems. This thesis shows a constructive method to derive the gravitational dynamics from prescribed matter dynamics. It can be applied to any matter theory on any tensorial background if the matter dynamics satisfy three basic physical conditions. The heart of this mechanism are the gravitational closure equations, a countable set of partial differential equations, whose solution determines the gravitational action functional. Practically, it can be very difficult to find general solutions to the closure equations. A significant simplification can be achieved by exploiting spacetime symmetries during the solution of the closure equations. This allows a direct derivation of the symmetry-reduced field equations. This thesis demonstrates explicitly how the standard model of particle physics and cosmological symmetries give rise to the Friedmann equations without knowledge of the Einstein equations. Additionally, the cosmological dynamics of general lin- ear electrodynamics are constructed. The result demonstrates how a refined theory of electromagnetism generalises the Friedmann equations. While this thesis considers cosmological symmetries, the methods presented here can be applied to any other spacetime symmetry.