We consider the Universe deep inside the cell of uniformity which is of the order of 190 Mpc. At these scales, the Universe is filled with inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies), which perturb the background Friedmann model. Here, the mechanical approach is the most appropriate to describe the dynamics of the inhomogeneities which is defined, on the one hand, by gravitational potentials of inhomogeneities and, on the other hand, by the cosmological expansion of the Universe. As an example, we consider the collision between the Milky Way and Andromeda in future.

Place: Physics Dept. Meeting Room, 2th floor, IST