  Development of the contemporary theory of physical phenomena in the microcosm
is considered to be a result of development of Einstein's ideas on a
possibility of the event space modification and on a possibility of stochastic
(Brownian) motion of free particles. One considers the space-time modification,
based on a new conception of geometry. In the framework of this conception any
geometry is obtained as a result of the proper Euclidean geometry deformation.
In the framework of this conception it is possible such a space-time geometry,
where the free particle motion appears to be stochastic, although the geometry
in itself remains to be deterministic. The stochasticity intensity depends on
the particle mass. It is small for particle of a large mass, and it is
essential for the particle of a small mass. The space-time geometry may be
chosen in such a way, that the statistical description of random world lines of
particles be equivalent to the quantum description (the Schr\"{o}dinger
equation). At such a description the quantum principles are not used. They can
be obtained as a corollaries of the statistical description of nonrelativistic
stochastic particles. The nonrelativistic quantum principles may not be used
for description of relativistic phenomena.
