Relativistic length in high energy physics

The role of relativistic length of high physics is discussed. Some approaches applied to description of experimental data on particle interaction at high energies is considered. Among them here are parton, reggeon, string models of elementary particles and hydrodynamical theory of multiple processes. It is noted that these approaches are closely connected with a concept of relativistic length and proceeding from this ''elongation formula''. In particular, on the base of this concept the solution of the known difficulty of hydrodynamical theory which contradicts the uncertainty principle is given. On the basis of elementary particle finiteness the conncetion of formation length with the relativistic length is established. It is noted that the linear increase of longitudinal distances with growing Lorentz-factor corresponds to the results of experiments on the study of the effect of motion on space dimensions of identical pion generation region. The obtained in these experiments indication to the increase in corresponding longitudinal dimensions as a result coul be considered as the most direct evidence in favor of relativistic ''elongation formula''