Abstract

The goal of the population dynamics theory is to describe the particle systems whose evolution includes a random motion (migration) and the birth-death processes. The theory must explain the visible effects of high irregularity (intermittency), clusterization etc. of the real populations. Mathematically, the problem can be reduced to analysis of the non-linear equations of the KPP (Kolmogorov – Petrovskii – Piskunov) type and the system of corresponding moment equations. Due to Ya.B. Zeldovich, the magnetic field of the Sun (or hot stars) can be presented phenomenologically as an ensemble of the quasi – particles (closed magnetic loops). Their evolution is similar to the population dynamics and leads to the understanding of the black spots as a manifestation of the intermittency of the magnetic fields. Almost all magnetic energy is concentrated in the spots. These spots cover a very small part of the surface of the Sun.