Accelerated expansion of the Universe driven by dynamic self-interaction
  We establish a new model, which takes into account a dynamic (inertial)
self-interaction of gravitating systems. The model is formulated by
introduction of a new function depending on the square of the covariant
derivative of the velocity four-vector of the system as a whole into the
Lagrangian. This term is meant for description of both self-action of the
system irregularly moving in the gravitational field, and back-reaction of the
motion irregularities on the gravity field. We discuss one example of exact
solution to the extended master equations in the framework of cosmological
model of the FLRW type with vanishing cosmological constant. It is shown that
accelerated expansion of the Universe can be driven by traditional matter with
positive pressure (e.g., dust, ultrarelativistic fluid) due to the
back-reaction of the gravity field induced by irregular motion of the system as
a whole; this back-reaction is shown to be characterized by the negative
effective pressure.
