Jammed Particulate Systems
with Eric Corwin, PhD, assistant professor in the department of physics at the University of Oregon
"The hardest geometry problem in the world is at the bottom of a bucket of sand."
The study of jammed systems began as a culinary curiosity in 1727, when the Reverend Stephen Hales studied how peas pack when compressed in an iron pot. Fill a pot with peas and you can run your hand through them, because they can flow out of the way much like a liquid would. But as pressure, and thus the density, is increased, you will find that there is a critical point, above which the peas “jam” into a stable amorphous solid. This behavior is very general. Pretty much everything composed of discrete chunks large enough that thermal fluctuations can be ignored can go through a jamming transition: colloids in solution, a pile of sand, a jar full of candies, even cars in a traffic jam.
We understand the universe now so much better than Hales did in 1727, yet we still don't have a robust understanding of why things jam the way that they do. The great successes of modern physics have been reductionist. Equilibrium systems are understood by breaking them into smaller and simpler component parts. However, this approach does not work with jamming, wherein all of the interesting behavior arises only at the scale of many many particles (and indeed the properties of the constituent parts is all but immaterial), leading to a "post-modern" approach to physics.
Eric Corwin is an assistant professor of physics at the University of Oregon. His doctoral degree is from the University of Chicago and he completed a post-doc at New York University before coming to Oregon. His research is dedicated to the study of complex systems far from equilibrium. He studies granular materials, jamming in 2d, 3d, and higher dimensions, geometric fustration, complex flows, particles moving on vibrated fluid surfaces, and fluctuation dissipation theorems.
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