Physics Colloquium - Friday, April 28st, 2006, 4:00 P.M.
E300 Math/Science Center; Refreshments at 3:30 P.M. in Room E200
Squeezing some new facts out of glasses
University of Massachusetts, Amherst
Molecules in a glass are relatively immobile even though they are arranged in much
the same way as in a freely-flowing liquid. There are two broad classes of
explanations for this state of dynamical arrest: one set of ideas explains it in
terms of the density of these systems. When a liquid contracts on cooling,
molecules that were already hindered in their motion by the dense packing in a
liquid now find no room at all to rearrange themselves. Another explanation is that
lowered temperature renders molecules too inactive to explore an increasingly
mountainous free energy landscape. I will discuss experiments in which we separate
unambiguously the effects of volume restrictions and lowered temperature in a
common glass-forming system.