Nowhere to hide: closing in on cosmological homogeneity
  Homogeneity is a crucial, but poorly tested, assumption in cosmology. We
introduce a new approach which allows us to place limits on the presence of
localized structures within essentially our entire observable volume, using
cosmic microwave background secondary anisotropies. We find that structures
cannot exceed roughly 20 times their expected amplitude over most of our
observable volume. Similarly, we place tight constraints on statistical
inhomogeneity within our volume, performing the first power spectrum
reconstruction using secondary anisotropies alone. We find that the standard
model passes this important new consistency test. Our approach probes
homogeneity over vastly larger volumes and scales than previous studies based
on surveys.
