Martin A. Fisher School of Physics

September 3, 2024

Berko Syposium - Gzang 121

Bennett Sessa, Brandeis

Abstract: The hydrodynamics of many living systems -- from morphogenesis to mitosis -- involve, in part, a dynamic competition between bulk active stresses and interfacial tension. We mimic this competition experimentally to understand how activity and capillarity compete to generate functionalized structures. A microtubule-driven active liquid is embedded in a binary, polymeric liquid that phase separates, forming active droplets surrounded by a passive background. Fluctuations in active stress near the boundary induce spontaneous curvature changes in the soft interface. The complex coupling between the bulk active fluid and deformable interfaces creates several exciting phenomena. First, we characterize a nonequilibrium analog of the classic Saffman-Taylor instability using both experiment & theory. Second, we describe how nonreciprocal coupling between the active fluid and interface drives asymmetric fluctuations. Our work supports the claim pressure in active systems is generally not a state variable but rather depends on mesoscopic details. We end with an outlook on time-reversal asymmetry in active systems. Altogether our work demonstrates active droplets exhibit rich hydrodynamic and thermodynamic behavior that can help us better understand the fundamental nature of nonequilibrium living systems.

September 17, 2024

Marc-Andre Pleier, BNL

Abstract: Particle colliders and their experiments have played a crucial role in discovering the fundamental building blocks of our universe and the forces between them. I will give a glimpse into the many ideas for future accelerators that are being discussed before outlining the feasibility study under way for the next major facility at CERN. Its goal is to study the latest discovered particle - the Higgs boson - as well as the overall consistency of the theoretical framework we call the Standard Model of particle physics in more depth to address some of the unsolved mysteries of our universe.

October 1, 2024

October 15, 2024

October 29, 2024

November 12, 2024