2.3 Comparison with theory
Structures in the universe are used to deduce the structure and the history of the universe. Some methods employed are statistical applied to ensembles of particles, assumed to be indistinguishable. Studies of time-dependent particle properties are required in order to either ascertain the validity of this assumption or to correct the measured properties appropriately.
World models needed for the comparison with observational results will be described in Sect. 3. The simplest models require that the clustering properties of matter disappear on sufficiently large scales. The observational study of large-scale structures serves to determine the types, scales and degrees of clustering, the possible causes of clustering and the scale size above which uniform distribution becomes apparent (or not).