Ordered and Disordered Motion in Dense Active Materials

Abstract

We discuss how the non-equilibrium driving forces introduced by the natural biological activity or by physical self-propulsion mechanisms generically affect the structure, dynamics and phase behavior of dense active media. We use theory and computer simulations to analyze simple models of such active materials. We borrow concepts from the equilibrium physics of amorphous and crystalline materials to provide a physical understanding of experimental observations performed with more complex systems such as self-propelled colloidal and granular systems, biological tissues, and bacterial colonies.