Abstract

The basic assumptions in the physical theory of Brownian motion are analized and the arbitrary character of certain aspects of the current theories is emphasized. The most serious limitations of the theory arise from the fact that in the theory, the elementary processes of the individual collisions are nowhere discussed. However, it is shown that the encounters between stars under their Newtonian inverse square attractions considered in Stellar Dynamics provides, in virtue of the peculiar character of inverse square forces, a case in Brownian motion in which all phases of the problem can be explicitly analyzed. Thus, the separation, of the effects of encounters into a dynamical friction and a random fluctuation is explicitly demonstrated from a direct analysis based on the dynamics of the encounters themselves; similary, the ratio of the frictional to the diffusion coefficients can also be shown to have the value which is required for the restoration and maintenance of a Max‐wellian distribution of velocities from any arbitrary initial distribution. ‐ S. C.