CMP Seminar
		     Monday, March 25, 2002
	4:10 p.m., Room 224 Physics-Astronomy Building

		      Refreshments at 3:45

	The Physics of the Colloidal Glass Transition

			   Eric Weeks
			Emory University

Are glasses merely extremely slow liquids, and if so, why are
they many orders of magnitude more viscous than conventional
liquids?  We study concentrated colloidal suspensions, a model
system which has a glass transition.  By using a confocal
microscope to follow the three-dimensional motion of colloidal
particles, we can directly observe the microscopic behavior
responsible for the macroscopic viscosity divergence of glasses.
Near the glass transition we find that particle dynamics are
heterogeneous in both space and time.  The motion of particles
can be characterized by a dynamic length scale which grows as
the glass transition is approached, which might explain the
viscosity divergence.

Our group's more recent work has studied two new problems. The
first is the non-equilibrium behavior of the colloidal
glasses themselves, which have properties which change over
time ("aging").  We are attemping to describe the microscopic
details of the aging process.  The second problem we're studying
is the response of dense colloidal systems to a small local
perturbation, applied by adding a magnetic particle into the
colloidal suspension and then moving that particle with an
external magnet.  We're studying how the response to this type
of perturbation changes near the glass transition.