Year 2026
 | Seminario Matematico e Fisico di Milano |
| Marcel Guardia
Universitat de Barcelona
Unstable motions in Celestial Mechanics
Wednesday, March 04 2026, at 14:30
aula C03 - Via Mangiagalli 25 - Università degli Studi di Milano |
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Abstract
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One of the oldest problems in dynamical systems is the stability of the Solar System. That is, consider N bodies moving following Newton's law of gravitation, one of them with large mass (the Sun) and the
others with small masses (the planets). If one neglects, the gravitational interaction between planets, the classical Kepler's laws assert that the planets move on ellipses. Then, one wants to understand whether the effect of the planet's mutual attraction causes long term changes on the shape and relative position of the Keplerian ellipses.
Nowadays, it is known that the answer to the stability of the Solar system is rather nuanced and that stability and instability coexist for nearby initial conditions. In this talk I will explain how to
construct unstable motions in this model, which lead to drastic changes in the semimajor axes, eccentricity and inclination of these ellipses. |
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| Seminario Matematico e Fisico di Milano |
| Luigi Ambrosio
SNS Pisa
Well posedness of ODE's for nonsmooth velocities and in non Euclidean ambient spaces: a survey
Wednesday, January 28 2026, at 14:00
aula U6-30, Dipartimento di Matematica e Applicazioni - Università Milano - Bicocca | |
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