Prof. Raymond L. Orbach, UT-Austin

"Managing Chaos: A Statistical Approach"

Coffee and cookies will be served at 3:45pm in RLM 4.102

Abstract: The best definition of chaos comes from Lorenz: “When the present determines the future, but the approximate present does not approximately determine the future.” More colloquially, “Does the flap of a butterfly’s wings in Brazil set off a tornado in Texas?” The nature of chaos will be addressed through a model system that can be explored experimentally: spin glasses. Chaotic behavior has been predicted for small changes in temperature, and observed in any number of experiments. What is more surprising is that the chaotic state appears to be reversible. That is, when chaos is observed as a consequence of a reduction in temperature, the system seems to start over: “the distribution of free energies is reshuffled. The states of lowest energy are not the same at different temperatures, meaning that the thermodynamic equilibrium phase is completely different from one temperature to another.” The re-initialization is termed “Rejuvenation.” The remarkable property is that the rejuvenated state is recovered after lowering the temperature and then increasing it back to where chaos took place, termed “Memory.” This talk will discuss a statistical approach to chaos: a “rare-event-driven phenomenon,” and discuss the nature of rejuvenation and memory. In essence, “managing chaos.”