Effect of collisionless particles on the growth of gravitational disturbances in an isotropic world

It is shown that the kinetics of processes of interaction between gravitational perturbations and collisionless particles (neutrinos) results, during the ultrarelativistic stage of expansion of the Universe, to a behaviour of long-wave gravitational perturbations which differs qualitatively from that obtained previously providing the energy density of the collisionless particles comprises more than 5/32 of the total energy density. An important feature of the new long-wave asymptotes in their oscillatory character. Asymptotes are also obtained for high-frequency perturbations in an isotropic world by taking into account the effect on the perturbation of a gas consisting of collisionless particles