File:Cosmic Topology fig4b.jpg

The Cosmic Crystallography Method in the Poincaré Dodecahedral Space. In this histogram for pairwise separations calculated in a PDS with $\Omega_0 = 1.1$, the presence of spikes signals a multi-connected topology, their positions reflect the size of the fundamental domain (a dodecahedron), and their relative heights characterizes the group of transformations that glue together the opposite faces of the dodecahedron. Although the main spike is situated at a spectral shift too large to be detectable, the first one is at $z \approx 1.5$, accessible to the deep observational surveys expected in this decade.