A. Fernandez-Nieves is an ICREA Professor in the Department of Condensed Matter Physics at the University of Barcelona, Spain. His research interests are in experimental soft condensed matter with recent work on partially ordered fluids, colloidal crystals and glasses, and active matter. A recurring theme is the presence of defects in the order and how they sense and respond to the local geometry, the local environment and the system’s inherent activity. He is also interested in fluid mechanics and hydrodynamic instabilities.