Question Isotropy
  The "cosmological principle" was set up early without realizing its
implications for the horizon problem, and almost entirely without support from
observational data. Consistent signals of anisotropy have been found in data on
electromagnetic propagation, polarizations of QSOs and $CMB$ temperature maps.
The axis of Virgo is found again and again in signals breaking isotropy, from
independent observables in independent energy regimes. There are no
satisfactory explanations of these effects in conventional astrophysics.
Axion-photon mixing and propagation in axion condensates are capable of
encompassing the data.
