We see the world as flowing matter. We design experiments that capture the fundamental dynamics of a vast array of fluid flows: from blood stream to industrial reactors, from aerosol transport to atmospheric precipitation. The common theme is the coexistence of multiple phases interacting over a wide range of scales, exemplified by the collective behavior of particles. Our favorite tool is imaging, from high-​speed cameras to medical diagnostics. Because we use fluid dynamics as a lens to understand different problems, we join forces with world experts in other disciplines related to energy, health and the environment. This creates a fertile environment for our students to discover their true passion.