Rebuilding the foundations of planet formation: proto-planetary disc evolution

With thousands of exoplanets known, we have truly entered the exoplanet era. Explaining the huge diversity of observed exoplanetary systems remains however a big challenge. The only way we have to study planet formation is to study the environments in which they form, proto-planetary discs: to understand planets, we have to understand discs and the physical processes happening in them.The field of proto-planetary discs is currently being shaken by the crumbling of viscous theory, the traditional paradigm used to describe how discs evolve in time. The paradigm relied on the presence of turbulence, which affects a myriad of processes of planet formation. The crumbling of viscous theory thus has ramifications across our entire understanding of planet formation.How can we rebuild the foundations of planet formation? Thanks to advances in observational capabilities, we can now perform large surveys of proto-planetary discs and study the evolution of their properties (mass, radius, mass accretion rate). Over the last few years I played a leading role in showing how to use this information to guide and constrain models of disc evolution, computing quantities from the models that can be directly compared to observations.Building on my expertise, at the convergence of theory and observations, I propose a) to develop quantitative models of an alternative paradigm of disc evolution in which discs evolve under the influence of disc winds rather than viscously. The long-lasting impact of DiscEvol will be to deliver a new standard model of disc evolution tested against the existing data from observational surveys. DiscEvol will also b) reassess how crucial steps of the planet formation process, such as the accretion of solids onto growing planetary cores and planetary migration, differ in a disc evolving under the influence of winds. Altogether, this program will bring the link between models and observations of planet formation in discs to a new level.