Gjesteforelesninger og seminarer
Kommende 5 dager
Michal Michalowski, Royal Observatory Edinburgh, School of Physics and Astronomy, The University of Edinburgh
Enrico Fermi and the birth of modern nonlinear physics
In the early fifties in Los Alamos E. Fermi in collaboration with J. Pasta and S. Ulam investigated a one dimensional chain of equal masses connected by a weakly nonlinear spring. The key question was related to the understanding of the phenomenon of conduction in solids; in particular they wanted to estimate the time needed to reach a statistical equilibrium state characterized by the equipartition of energy among the Fourier modes. They approached the problem numerically using the MANIAC I computer; however, the system did not thermailize and they observed a recurrence to the initial state (this is known as the FPU-recurrence). This unexpected result has led to the development of the modern nonlinear physics (discovery of solitons and integrability). In this seminar, I will give an historical overview of the subject and present the different approaches that have been proposed in the last 60 years for explaining this paradox. Very recent results on the estimation of the time scale and on the explanation of the mechanism of equipartition will also be discussed.
Flere kommende gjesteforelesninger og seminarer
Morten Bo Madsen, Associate Professor, Astrophysics and Planetary Science, Niels Bohr Institute
Tamara Brocerick (Massachusetts Institute of Technology) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.
Tomi Koivisto, NORDITA
By Malin Pinsky from Rutgers University, United States