  The relativistic effect of energy increase in a particle freely moving in
vacuum is discussed on the basis of quantum field theory and probability theory
using some ideas of super-symmetrical theories. The particle is assumed to
consist of a "seed" whose energy is equal to the particle rest energy and whose
pulse is equal to the product of the particle mass by its velocity and of a
"fur coat" - the system of virtual quanta of the material field - vacuum. Each
of these quanta possesses the same energy and pulse as the "seed" but have no
mass. The system of the quanta is in a state being the superposition of quantum
states with energies and pulses multiple of the "seed" energy and pulse. The
virtual quanta is created (or destroyed) in of such states. The probability of
creating a quanta in any state is the inverse of the relativistic factor, and
the average number of the quanta making up the "fur coat" with a "seed" is
equal to this particular factor. The kinetic energy and the relativistic
addition to the particle pulse are interpreted as the average magnitude of the
energy and the pulse in the system of the virtual quanta that constitute the
particle "fur coat".
