The current understanding of the dynamics of the physical world is in terms of three fundamental interactions: the gravitational, electroweak and strong forces. These are expected to account for the full complexity of the world, ranging from subnuclear ($10^-20$ m) to cosmological ($10^26$ m) scales. In spite of this huge range in scales, all forces are described in a coherent manner by similar theories based on the two major revolutions in physics of the twentieth century, quantum physics and relativity. These theories are constructed using field theory, geometry and group theory.

The mathematical investigation of these three theories and possible extensions are pursued in the group by the team Geometry, Physics and Symmetries.

The Particle team is specialized in the confrontation of models with observational data on subnuclear scale, using in particular large-scale numerical simulations in lattice QCD, effective field theories, low-energy precision experiments and dark matter searches.

During the last twenty-five years cosmology has witnessed a breathtaking acquisition of new observational data that appear to challenge the theory. The Cosmology team concentrates on the two major enigmas, the accelerated expansion of the universe and the anomalies in the dynamics and the clustering of matter at cosmological scales.

The coherence of the overall picture is broken in one point: In spite of intense efforts, we still lack a quantum description of gravity. The Quantum Gravity team has taken up this challenge and in spite of being the youngest of the four teams, it is already one of the leading teams world-wide. Two of its current themes are the investigation of what happens at the center of black holes and the physics of the big bang.