Modified Averaging Processes in Cosmology and the Structured FRW model

Understand

We study the volume averaging of inhomogeneous metrics within GR and discuss its shortcomings such as gauge dependence, singular behavior as a result of caustics, and causality violations.

• To remedy these shortcomings, we suggest some modifications to this method.
• As a case study we focus on the inhomogeneous structured FRW model based on a flat LTB metric.
• The effect of averaging is then studied in terms of an effective backreaction fluid.