"The history of spin glass may be the best example I know of the dictum that a real scientific mystery is worth pursuing to the ends of the Earth for its own sake, independently of any obvious practical importance or intellectual glamour."

Philip W. Anderson
(Nobel Laureate 1977)

Giorgio Parisi, born 1948 in Rome, Italy and currently Professor at Sapienza University of Rome, was awarded one half of The 2021 Nobel Prize in Physics for "groundbreaking contributions to our understanding of complex physical systems" and in particular "for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales".

In this talk I will give an introduction to the theory of spin glasses, following the historical development of the field culminating in an inspired series of papers by Giorgio Parisi describing the exact equilibrium solution of the Sherrington–Kirkpatrick model using the Replica method. Parisi's discovery is considered to be among the most important contributions to the theory of complex systems. I will conclude the first half of my talk with the interpretation of the low temperature spin glass phase also developed by Parisi and coworkers, and show the recent direct experimental realization of aspects of the solution in systems of random lasers.

Despite what P. Anderson so eloquently wrote in 1988, the theory of spin glasses and its methods have developed a strong interdisciplinary character with widespread applications in artificial intelligence, machine learning, information science, mathematics and computer science. I will describe a select few applications focusing on problems that can be cast (or recast) as stochastic processes on graphs, collectively known as graphical models.

Guenter Schneider is Associate Professor in Physics at Oregon State University. His interests are in computational physics, inculding biological and solid state systems.

Location: Participate by Zoom or join colleagues in Wngr 149. Masks required. Please ask people about their social distance preferences before seating yourself next to someone. The colloquium speaker will present remotely.