Active particles contain internal degrees of freedom which take up energy from their surroundings and, in dissipating it, execute systematic movement. This definition obviously includes motile organisms, whether macroscopic or microscopic, cytoskeletal filaments with motors and ATP, and pumps in the cell membrane; monolayers of agitated granular rods are a less obvious example. My talk will survey our recent work on order, fluctuations and flow instabilities in this strange kind of matter.

Bangalore