  A tennis ball is not expected to penetrate through a brick wall since a
motion under a barrier is impossible in classical mechanics. With quantum
effects a motion of a particle through a barrier is allowed due to quantum
tunneling. According to usual theories of tunneling, the particle density
decays inside a classical barrier resulting in an extremely slow pentration
process. However, there are no general laws forbidding fast motion through
classical barriers. The problem addressed is investigation of unusual features
o quantum tunneling through a classic static barrier which is at least
two-dimensional. Here we show that penetration through such barrier can be not
slow. When the barrier satisfies the certain conditions, a regime of quantum
lens is possible with formation of caustics. De Broglie waves are reflected
from the caustics, interfere, and result in a not small flux from under the
barrier. This strongly contrasts to the usual scenario with a decaying
under-barrier density. We construct a particular example of fast motion through
a classical barrier. One can unexectedly conclude that, in principle, nature
allows fast penetration through classical barriers which against common sense.
The phenomenon may be responsible for a variety of processes in labs and
nature. For example, tunneling in solids may occur with a different scenario,
in biophysics and chemistry one can specify conditions for unusual reactions,
and evanescent optical waves may strongly change their properties. In condensed
matter and cosmic physics there are phenomena with misterious reasons of an
energy emission, for instance, gamma-ray bursts. One can try to treat them in
the context of fast escape from under some barriers.
