Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

We provide an overview of the hydrodynamic theory of multiple production
processes at high energies.
The short historical excursus to this theory development from the fundamental
conceptions
of Heisenberg, Fermi, Landau to the present-day status is given
and the close connection between its main ideas and
quark-gluon plasma conception is traced.
The problems of quark-gluon plasma diagnostics in nucleus-nucleus interactions
are discussed.
We present the possible interpretations of peculiarities being
observed in ultrarelativistic nuclei collisions experiments at accelerators
SPS and RHIC and discuss the prospects for the observation and investigation
of quark-gluon plasma properties at collider LHC.
The main features of cosmic $\gamma$-flashes-up are explained in the framework
of hydrodynamic theory of collisions of neutron stars and black holes.