Non-equilibrium behaviour of colloidal systems.*

There is an explosion of interest in the collective properties of active matter. This interest is understandable because it is exciting to step outside the confines of the classical statistical mechanics that was developed to describe systems at or near equilibrium.

However, many puzzles remain about the way in which active matter is propelled. In my talk, I shall discuss some of these problems and indicate how the study of colloidal systems in the presence or absence of gravity might help us gain a better understanding of the physical processes that drive active matter.