Seminar of Theory of Relativity and Gravitation

We show how a class of exact solutions of Einstein's equations (the Szekeres models) can be worked out to describe an arbitrary number of evolving over-densities and density voids whose spatial location at all times can be prescribed from standard early Universe initial conditions. These configurations provide a fully relativistic and non-perturbative (but coarse grained) description of actually observed and/or inferred structures in the 100 Mpc (or larger) scales, which are normally examined by Newtonian n-body simulations or perturbative methods. These networks of evolving multi-structure configurations have an enormous potential for application to address a wide range of open theoretical and observational issues in Cosmology.