The variance of the CMB temperature gradient: a dependence on the spatial orientation and anisotropy of a multiply connected Universe
The study developed a model-independent method using rho-statistics and mask-sweeping to find patterns in CMB temperature maps, specifically looking for evidence of a cubic 3-torus topology. The method confirmed a linear relationship between the size of the torus (L) and the gradient variance ($ ho$), suggesting our Universe has a finite size around 3 Hubble lengths.