Digital Publication of Professor Alessandro Morbidelli’s Opening Lecture

Alessandro Morbidelli

Determinism and Stochasticity in Planetary Formation Processes

For centuries, it was believed that all planetary systems, by virtue of the universality of physical laws, resembled our own. However, the discovery of numerous exoplanets has revealed their great diversity.

This book presents the current state of knowledge regarding the structure of known planetary systems, while situating our own Solar System within this vast context. How can universal laws give rise to such diversity? Among the processes involved in planet formation, some are seemingly deterministic, while others are more complex and can lead to stochastic behavior. This sensitivity of planet formation to contingencies invites us to reflect on the probability of the existence of planets similar to our own elsewhere in the galaxy, as well as on the possibility of life developing on exotic worlds.

Morbidelli, A., Determinism and Stochasticity in Planetary Formation Processes , Paris, Collège de France, “Opening Lectures ” series, n^o. 327, 2025.

Alessandro Morbidelli is a planetary scientist. He directed the CNRS National Planetary Science Program from 2010 to 2018. An associate member of the French Academy of Sciences since 2015, he was elected in 2023 as a professor at the Collège de France, holding the chair in Planetary Formation: from Earth to Exoplanets.