Brownian Motion

Abstract

Brownian motion is the irregular and perpetual agitation of small particles suspended in a liquid or gas. In 1828 the Scottish botanist Robert Brown (1773--1858) published the first extensive study of the phenomenon. Brown showed notably that this motion equally affects organic and inorganic particles, suggesting a physical rather than a biological explanation [1]. Developments in thermodynamics and the kinetic theory in the second half of the nineteenth century led several scientists to consider Brownian motion as a visible consequence of thermal molecular agitation; but it was not until the early twentieth century that a convincing quantitative description and theoretical explanation of the motion was worked out.