Wednesday, September 12, 2012

Copernican principle

what ways are there for testing the isotropy and homogeneity of the Universe on large scales? to what extend are those symmetry assumption tested and how would a violation impact on FLRW-models?

1 comment:

  1. Currently, the CMB provides the strongest evidence for isotropy. Homogeneity is notoriously hard to measure, because most observations are restricted to our past null-cone and therefore it is difficult to differ between a spatial evolution and an evolution in time. However, there is one very elegant method based on the kSZ effect, which I'd like to propose as a way to measure homogeneity:

    To answer your second question: There is strong observational evidence for isotropy. Homogeneity is merely an assumption which is consistent with observational data. A violation of either of these properties would change the way we interpret cosmological data (the distance-redshift relation, for instance).