Tel-Aviv University
School of Mathematical Sciences
Department Colloquium
*** Note the special time and place ***
Wednesday, December 30, 2009
Schreiber 309, 13:10
Michael Hochman
Princeton University
Zero temperature limits of Gibbs states
Abstract:
In statistical mechanics, Gibbs states are probability distributions on
the space of configurations of a system which minimize the mean "free
energy", i.e. minimizes a potential and maximizes the entropy. At each
temperature one finds different Gibbs states, reflecting the fact that the
entropy contribution scales linearly with the temperature. It can happen
that several Gibbs states exist at a given temperature (a "phase
transition"); this is interpreted physically as saying that the material
can take different stable forms, e.g. at room temperature Carbon is stable
both as graphite and as diamond. Phase transitions typically happens in
multidimensional models when the temperature is low, and there is a large
literature on this subject. In this talk I will discuss a less known
phenomenon, namely that as the temperature is decreased to 0, the
corresponding Gibbs states may not converge. Although related to phase
transitions, this behavior is of a slightly different nature, and can
occur in systems without phase transitions, even in (infinite volume)
one-diensional lattice models over discrete state spaces and fast-decaying
potentials. This talk will not assume familiarity with statistical
mechanics and is based on joint work with Jean-Rene Chazottes.