On the 24th of June Dr. Christodoulidi presented her recent results on the Fermi-Pasta-Ulam-Tsingou (FPUT) model, a Hamiltonian model composed of N weakly nonlinearly coupled harmonic oscillators.
After introducing the FPUT model, she discussed its non-ergodic and integrable-like behaviour which is puzzling the scientific community for over 60 years. A new approach to the problem was suggested by regarding the FPUT model as a perturbed Toda lattice, the latter of which is completely integrable. This idea goes back in a work of Flaschka and implies that the Toda integrals are the relevant dynamical observables for studying the FPUT model.
The talk closed by proposing a method of determining slow diffusion to estimate the two critical timescales, namely: i) the time of stability t0, where FPUT behaves as Toda, and ii) the time to equilibrium teq.