Sidney Nagel and the physics of everyday life

1:32:59everyday phenomena and finding beauty in nature's disordered systems. Recognizing Dr. Sydney Nagel, the Stein Fryer Distinguished Service Professor of Physics at the University of Chicago, Nagel has spent decades investigating things that we rarely stop to question every day. Why does spilled coffee leave a ring? Why can sand pour like a liquid and then sit in a pile and hold its shape? a question I've never asked myself. With the support of the National Science Foundation and the Department of Energy, he and his collaborators have turned everyday puzzles into these

1:33:39experiments that reveal deeper physical principles. And this is something I've certainly never thought about, but is a very interesting question. What we're looking at here is a dried coffee drop about 2 cm across from the team's original research. As we can notice, there are these darker regions around the edge. Those particles all started out spread through the liquid >> in some contiguous fashion. So why did they ultimately end up concentrating and creating that outline? Nagel and his colleagues showed how evaporation can flow inside

1:34:21the drying drop, which I've never thought about, but now makes total sense. Carrying particles through towards the edge and concentrating them there. Understanding that process matters for things that actually matter to us every day, like inkjet printing. Mhm. >> If you want to drop a liquid ink on a paper, you need to know how it's going to ultimately land and spread so you get actual the actual letters that you want uh when the ink dries. And across his work with droplets and grains, there's a bigger question. How do we find predictable behavior in materials whose parts are not neatly arranged? Which is a very very interesting

1:35:02question. Yeah. And physics has a reputation for not caring about that. Okay, physicists have a reputation for not caring about neatly or for not caring about not neatly arranged stuff, right? We care about stuff that's near zero Kelvin like quantum properties. We've done the quantum computing stuff like nice systems that obey >> nice laws. You know, the cow is a sphere is a is a favorite sort of comic that we talk about. the formation of the universe. Everything is nice and isotropic. Collisions of black holes, again, black holes have no hairs and it's just like two little bodies. Okay, fine. The equations of GR are a little

1:35:44chaotic but >> it's not really disordered in a sense. And Sydney Nagel >> was curious about much more modest things in his life. the texture of our world, the physics of a raindrop as it stretches and falls from an overhang, the spill of a coffee cup. And you know, in one of his interviews, he says that no one thought you'd find basic truths by looking at these sorts of things. But the fact that we don't know how to think about answering these questions means that there's some fundamental physics that we don't know. >> And that's the questions, those are the types of questions that he's trying to answer. What's the mechanism? What

1:36:24carries coffee particles to the edge to give us that nice black marking? And the answers require us to look at flows, forces, geometries, and time scales that maybe our everyday intuition barely ever registers. >> Now, Nagel is a physicist at the University of Chicago and one of the pioneers of a field called soft matter physics. In 2023, he received the American Physical Society's Medal for Exceptional Advancement in Research. And the work that we're going to follow spans about three decades of work, many collaborators. I want to again trace five papers in order from the falling drop in 1994 to the stuff that he's been

1:37:05doing in 2025. We're going to start with