  An open (having no physical boundaries) baryon symmetric system is considered
in a flat space-time. We assume that a space is uniformly filled with
electromagnetic radiation and material objects, and the system is isotropic in
any inertial reference frame. It means that a coordinate-momentum distribution
of radiation and material objects does not depend on a reference frame, and the
system should be in a state of chaotic relativistic motion. The dominant
interaction processes are like-matter merge, unlike-matter annihilation and
pair production. In this approximation we came to the conclusion that matter
and antimatter exist in a form of mix of material objects characterized by a
stationary baryon symmetric mass distribution in a broad mass range. In other
words, a matter-antimatter space separation takes place.
