I will first introduce a model known in the physical literature as the Lévy-Lorentz gas. The model describes the continuous-time motion of a particle on the real line in the presence of a random array of marked points, whose nearest-neighbor distances are i.i.d. and long-tailed (with finite mean but possibly infinite variance, with controlling parameter $\alpha$). I will give a brief summary of the know results about transport properties for this model. I will then present a related model that may be viewed as a mean-field version of the Lévy-Lorentz gas.
SEMINARI DI FISICA MATEMATICA
The ESA mission Gaia, which is currently surveying the sky from the
Sun-Earth L2 Lagrangian Point, is providing astrometry of stars and
asteroids at few mas. The first Gaia Data Release, which
includes 2 millions of stars with position, parallaxes, and proper
motion and a position catalog of 1.1 billion of stars, has already
shown the strength of this unprecedented power of investigation.
The next Gaia data release in April 2018 will contain not only
billions of stars with proper motions and parallaxes, but also the
The history of asteroid families, from their discovery back in 1918, until the present time, is briefly reviewed. Two threads have been followed: on the development of the theories of asteroid motion and the computation of proper elements, and on the methods of classification themselves. Three distinct periods can be distinguished: the first one until mid-1930s, devoted to discovery and
This is a two-hour seminar, with the first part dedicated to introducing basic concepts in infinite ergodic theory.