It is a random walk. The diffusion constant is proportional to the coefficient of friction of the particle in the fluid. This reflects the profound idea, first proposed by Einstein, of a fluctuation-dissipation relation. Friction and diffusion and two sides of the same coin...

This looks like a random walk. If the friction is a random process how is it that the particle slows down in the direction of travel overall?

ReplyDeleteIt is a random walk. The diffusion constant is proportional to the coefficient of friction of the particle in the fluid.

ReplyDeleteThis reflects the profound idea, first proposed by Einstein, of a fluctuation-dissipation relation. Friction and diffusion and two sides of the same coin...