The cosmological principle is not in the sky

Understand

The homogeneity of matter distribution at large scales, known as the cosmological principle, is a central assumption in the standard cosmological model.

• The case is testable though, thus no longer needs to be a principle.
• Here we perform a test for spatial homogeneity using the Sloan Digital Sky Survey Luminous Red Galaxies (LRG) sample by counting galaxies within a specified volume with the radius scale varying up to 300 Mpc/h.
• We directly confront the large-scale structure data with the definition of spatial homogeneity by comparing the averages and dispersions of galaxy number counts with allowed ranges of the random distribution with homogeneity.