Physical Society Colloquium

CAP Lecture

Brownian Motion: The Life Of Dancing Molecules

Gary W. Slater

University of Ottawa

Einstein's 1905 article on the random dynamics of small particles in fluids is perhaps not as famous as his other 1905 articles, but his theory of Brownian motion has had a huge impact in science. In this presentation, we will follow the history of this phenomenon, starting with the botanist Robert Brown, and we will look at its importance in various scientific disciplines including polymer science, analytical chemistry and biophysics. Two recent developments will be described in more detail: the thermodynamic ratchet and the calculation of exact diffusion co-efficients for Brownian particles on lattices. Actual movies of molecules undergoing Brownian motion will be used to discuss the fundamental nature of this phenomenon that has an effect on most biological processes.