  One of the main objectives of modern cosmology is to explain the origin and
evolution of cosmic structures at different scales. The principal force
responsible for the formation of such structures is gravity. In a general
relativistic framework, we have shown that matter density contrasts do not grow
over time at scales exceeding the cosmic screening length, which corresponds to
a cosmological scale of the order of two to three gigaparsecs at the present
time, at which gravitational interactions exhibit an exponential cut-off. This
is a purely relativistic effect. To demonstrate the suppression of density
growth, we have performed N-body simulations in a box with a comoving size of
$5.632\,{\rm Gpc}/h$ and obtained the power spectrum of the mass density
contrast. We have shown that it becomes independent of time for scales beyond
the cosmic screening length as a clear manifestation of the cosmic screening
effect.
