Comprendre l'évolution des galaxies avec la physique statistique

The aim of this presentation is to illustrate how methods derived from statistical physics can shed light on the complexity of the dynamic processes taking place within galaxies.

Presented by Jean Baptiste FOUVRY, astrophysicist at the IAP.

A galaxy, such as the Milky Way, has three main
dynamic properties:
* It consists of a finite number of stars (‘only’ one hundred
billion in the case of the Milky Way);
* Its evolution is governed by gravity (a long-range
force that cannot be stopped);
* The Milky Way is ‘sensitive’ (like a drum, it responds to
cosmic perturbations).

Such properties make it impossible to know exactly the position of
all the stars throughout the 10 billion years of its
existence. For example, what would have happened if the Sun had been born
elsewhere in the Milky Way? If the Milky Way had consisted of
ten times fewer stars? Or if the halo of dark matter
enclosing it had been ten times more massive?