BROWNIAN MOTION IS CHAOTIC. In case one needed any more persuasion that chaos is all around us, a Brussels-Maryland-Utah collaboration has for the first time demonstrated evidence for chaotic behavior in fluids at the microscopic level. The data consists of repeated viewings of a 2.5-micron particle suspended in water. A plot of the particle's position as a function of time is translated into a form which provides information about how the particle's position at one time correlates with the position at a later time. This analysis proved to bear all the hallmarks of chaotic behavior. The chief symptom of chaos is the tendency for particles that initially follow nearby trajectories to diverge quickly from one another. (P. Gaspard et al., Nature, 27 August 1998.)