Metric Renormalization in General Relativity

Understand

The averaging problem in general relativity concerns the difficulty of defining meaningful averages of tensor quantities and we consider various aspects of the problem.

• We first address cosmological backreaction which arises because the averaged Einstein tensor is not the same as the Einstein tensor of the averaged metric.
• It has been suggested that backreaction might account for the dark energy.
• We show numerically in the Buchert formalism that the corrections from (quasi)linear perturbations are only of the order of 10^-5 and act as a dark matter.