Thermal ratchet effect in ferrofluids

A. Engel

Institute for Physics, University of Oldenburg, D-26111 Oldenburg, Germany

Abstract
The extraction of directed motion from random fluctuations is an old and controversial problem in statistical mechanics with a long and interesting history . Although excluded by the second law of thermodynamics for equilibrium systems, rectification of fluctuations is possible in systems driven sufficiently far away from thermal equilibrium . The problem has gained renewed attention under the trademarks of ``thermal ratchets'' and ``Brownian motors'' due to its possible relevance for biological transport and the prospects of nano-technology. Figs 2, Refs 17.