Cosmic antigravity
  Possibility of gravitational repulsion in General Relativity is discussed and
astronomical data in favor of cosmological acceleration are described. The
problem of vacuum energy is emphasized and possible ways of its solution are
indicated. The main attention is payed to adjustment mechanism which in
principle could compensate originally huge vacuum energy down to cosmologically
acceptable value and to solve the coincidence problem of a close magnitudes of
the non-compensated remnants of vacuum energy and the energy density of the
universe at the present time. Finally possible modifications of gravity at
large scales which could induce accelerated cosmological expansion are
considered.
