A Brief Journey into the World of Active Matter

Active matter refers to systems composed of self-driven units that convert stored or ambient energy into systematic motion, thereby maintaining a state far from thermodynamic equilibrium. Such systems exhibit a wide range of phenomena not present in equilibrium systems — including flocking, motility-induced phase separation, breaking detailed balance, and the formation of patters — that cannot be captured by classical equilibrium statistical mechanics. Particle based descriptions are a common tool to model such active matter systems. Particular emphasis will be placed on connecting microscopic interaction rules to macroscopic behaviour for active matter systems ranging from swimming unicellular microalgae, over filamentous bacteria to chemically driven colloids in drying films.