  We show that the free relativistic wave equation which describes the particle
without or with rest mass has more than one part of energy spectrum. One part
of energy spectrum is beginning with rest energy and it is not limited by
above. This part of spectrum is called by us as normal. Another part of energy
spectrum is beginning with the zero energy . This part of spectrum is called by
us as anomalous since the zero energy corresponds to the infinite group
velocity.The presence of the zero in the energy spectrum permits to consider
the Bose-Einstein condensation. We show that the heat capasity has the finite
discontinuity at the condensation temperature. The last means that we have the
phase transition at the condensation point.
