Collective motions are reported in many living systems, ranging from bacterial colonies to large herds of buffalo. In the past 15 years, experimentalists have been incredibly creative in developing strategies to induce motion in soft matter systems of particles such as droplets, colloids and grains. It is now clearly established that collective motion emerges in such non-living systems as well, and a general theory has been successfully developed to describe this emergent behavior.
In this talk, I will review 2 or 3 examples of such fascinating systems, for which I will first describe the sometime intriguing mechanisms of motion. Then I will describe how one can understand and predict the onset of collective motion. Finally, I will move towards the description of new phases of matter, that can be obtained when onset of collective motion and structural ordering take place simultaneously. This will allow me to conclude with opening some perspectives on the design of active materials with yet unforeseen properties.
Olivier Dauchot, is Deputy Director of the CNRS Gulliver laboratory, at ESPCI, in Paris, His general interest is to develop model experiments for studying divided soft-matter and collective effects. Developing collaborations with theoretical teams is one of his hallmarks. He presently concentrates on active matter, and glass forming systems. Previously, Olivier was leading the Group Instabilities and Turbulence in CEA-Saclay. At that time, he brought significant contributions to the study of jamming in granular media, to that of chaotic mixing, as well as to the understanding of transition to turbulence.