Cosmic Homogeneity and Inhomogeneity

Sketch illustrating the dual nature of the Universe -- smooth on large scales but rough on small scales below a certain threshold scale of ~150Mpc. This resembles water -- homogeneous on large scales, but rough on molecular scales below about 100 nm. What sets the cosmic transition scale?


A more technical depiction of the above sketch: the power spectrum has a peak at the maximum structure scale.