Dr. William Klein
Title:
Nucleation, Critical Points and Phase Transitions in Metals and Earthquakes
Nucleation
is a process that plays an important role in areas as diverse as materials
science, earth science and the physics of the early universe. Physicists have
been trying to understand this process for over a century.
The
most widely used theory is the so called classical theory which postulates that
the critical or nucleating droplet has a well defined surface and distinct
volume and surface contributions to the nucleation barrier. In addition the
interior of the droplet is assumed to have the same structure as the stable
phase. While this theory works for several classes of systems it does not work
for problems that involve metals, polymers, plasmas and earthquake faults to
name a few. In these cases the presence of a long range interaction or an
effective long range interaction qualitatively changes the nature of the
nucleation process.
In this seminar I will
discuss the classical nucleation process and how this process is changed when
the interaction range increases. I will also discuss specific examples such as
nucleation in metals and earthquake fault systems.