Our chaotic Solar System

Abstract

According to a non-scientific dictionary, chaos is ‘the original mixture of elements that, following certain cosmogonical theories, existed before the creation of the Universe’. Lucretius — a disciple of the Epicurean doctrine -identifies chaos with the clinamen — the small deviation from the parallel free-fall trajectory of atoms in space which makes them encounter each other, create elements and therefore life. After being forgotten and rediscovered many times, chaos is now firmly back in the scientific literature. It plays an important role among apparently distant fields of study: fluid mechanics, medicine, computer science, economy, and quantum systems. The study of chaotic behaviour in celestial mechanics dates back to the pioneering work of Henri Poincaré on the three-body problem, whereas the powerful computing tools at our disposal nowadays allow us to investigate the chaotic behaviour of complex N-body gravitationally interacting systems. In doing so, fast and slow chaotic diffusion emerge as the driving forces shaping the dynamics of our Solar System.