  The evolution of the closed Friedmann Universe with a packet of short scalar
waves is considered with the help of the Wheeler--DeWitt equation. The packet
ensures conservation of homogeneity and isotropy of the metric on average. It
is shown that during tunneling the amplitudes of short waves of a scalar field
can increase catastrophically promptly if their influence to the metric do not
take into account. This effect is similar to the Rubakov-effect of catastrophic
particle creation calculated already in 1984.
  In our approach to the problem it is possible to consider self-consistent
dynamics of the expansion of the Universe and amplification of short waves.
  It results in a decrease of the barrier and interruption of amplification of
waves, and we get an exit of the wave function from the quantum to the
classically available region.
