  We propose a simple scenario which explains why our Universe appears
spatially flat, homogeneous and isotropic. We use the
Einstein-Cartan-Kibble-Sciama (ECKS) theory of gravity which naturally extends
general relativity to include the spin of matter. The torsion of spacetime
generates gravitational repulsion in the early Universe filled with quarks and
leptons, preventing the cosmological singularity: the Universe expands from a
state of minimum but finite radius. We show that the dynamics of the closed
Universe immediately after this state naturally solves the flatness and horizon
problems in cosmology because of an extremely small and negative torsion
density parameter, $\Omega_S \approx -10^{-69}$. Thus the ECKS gravity provides
a compelling alternative to speculative mechanisms of standard cosmic
inflation. This scenario also suggests that the contraction of our Universe
preceding the bounce at the minimum radius may correspond to the dynamics of
matter inside a collapsing black hole existing in another universe, which could
explain the origin of the Big Bang.
