Levich Institute Seminar Announcement, 10/30/2007
Tuesday, 10/30/2007
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Professor Sidney Nagel
University of Chicago
Department of Physics

"Jamming and the Low Temperature Properties of Glasses"


ABSTRACT


Why are some materials rigid and others, with seemingly identical structure, fluid? Both glasses and granular materials are amorphous systems of particles in which the dynamics is perched precariously near a transition between flow and structural arrest. Is there something generic about such transitions so that the freezing of a liquid into a glass can profitably be compared to the arrest of a flowing granular material as external stresses are reduced below the yield stress?

In the present talk, I will consider the jamming transition at zero temperature. There are many unique properties of this transition as it is approached from higher density. In particular, there is a dramatic contribution to an excess density of vibrational states at low frequencies which is reminiscent of the Boson peak seen in glasses. An analysis of the origin of these modes suggests a new approach to jammed materials and to the low-temperature excitations of glasses – an approach based not on disorder but rather on the weak connectivity of the structure.

BRIEF ACADEMIC/EMPLOYMENT BACKGROUND:

  • Ph.D., Princeton, 1974.
  • Stein-Freiler Distinguished Service Prof., Dept. Physics, James Franck Inst., and the College

CURRENT RESEARCH INTERESTS:

Experimental physics, condensed-matter physics, non-linear dynamics