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DTSTART;TZID=America/Chicago:20261019T160000
DTEND;TZID=America/Chicago:20261019T170000
DTSTAMP:20261005T102354Z
SUMMARY:2026 Stephen H. Davis Lecture: Dr. Sidney Nagel on "Memory Formation in Particle Packings"
UID:647040@northwestern.edu
TZID:America/Chicago
DESCRIPTION:Title: Memory Formation in Particle Packings  Speaker: Dr. Sidney Nagel\, University of Chicago  Abstract: A disordered solid created by packing spheres in a box has a myriad of stable configurations that defy straightforward enumeration and characterization. Since structure often determines function\, each distinct arrangement potentially corresponds to different material behavior. The question naturally arises: How many mechanically stable ways are there to pack N identical spheres in a box? This has the spirit of a “Fermi estimation problem\,” but one for which we do not have an answer: we do not know how to account for rearranging the particles to produce packings with different connectivity. We therefore resort to measurement.  Stable packings of N identical soft spheres in d dimensions lie at the minima of a vast (Nd)-dimensional potential energy landscape. Starting from random positions\, the particles can relax to mechanical equilibrium; all initial conditions that end at the same minimum belong to the same catchment basin. We find a very wide distribution of basin volumes. These results suggest how to understand the imprinting of memories in solids.  Bio: Sidney Nagel was educated at Columbia University (B.A. in 1969) and at Princeton University (Ph.D. in 1975). He did a postdoc at Brown and then moved to the University of Chicago in 1976 where he has remained and is now the Stein-Freiler Distinguished Service Professor in the Department of Physics and the James Franck and Enrico Fermi Institutes. Nagel is a condensed-matter experimentalist focusing on problems where the physics of disorder and far-from-equilibrium behavior play crucial roles. Of particular delight is when table-top experiments have analogs in disparate fields at wildly different scales. In particular\, he has studied the glass transition\, the phenomenology of granular material\, and the physics of jamming; he has also focused on pattern and singularity formation in fluid interfaces\, and the formation of stains left behind by evaporating liquid drops. A current interest is the investigation of memory formation in out-of-equilibrium matter. He has worked to make his science accessible to a broad public by emphasizing the inherent beauty of the phenomena he studies in the laboratory.   Zoom: https://northwestern.zoom.us/j/98030602428  -----  To subscribe to the Applied Mathematics Colloquia List send a message to LISTSERV@LISTSERV.IT.NORTHWESTERN.EDU with the command:  SUBSCRIBE esam-seminar FirstName LastName
LOCATION:Ford Motor Company Engineering Design Center\, ITW (Room 1.350)\, 2133 Sheridan Road\, Evanston\, IL 60208
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URL:https://planitpurple.northwestern.edu/event/647040
CREATED:20260929T050000Z
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LAST-MODIFIED:20260929T050000Z
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