Theory of Brownian motion due to fluctuations of the stress tensor of a fluid

Microscopic model is proposed which describes, the tionconservative interaction force between the surface of a spherical brownian particle and the molecules of the fluid corresponding to diffuse reflection of the molecules from the surface. The Fokker–Planck equation with the friction coefficient which is expressed in terms of this nonconservative force, is derived for the distribution function of the brownian particles. Evaluation of the expression obtained in the case of brownian motion in the viscous incompressible fluid leads to the classical Stokes formula.