The Poincaré Seminar is held twice a year at the Institut Henri Poincaré in Paris. This volume contains the lectures of the 2002 seminars. The main topic of the first one was the vacuum energy, in particular the Casimir effect and the nature of the cosmological constant. The second one concentrated on renormalization, giving a comprehensive account of its mathematical structure and applications to high energy physics, statistical mechanics and classical mechanics.
Students will find excellent introductions to the subjects with further lectures leading to the frontiers of experimental and theoretical research, scientists will profit from contributions by outstanding experts.

I: The Vacuum Energy.- On the Cosmological Constant Problems and the Astronomical Evidence for a Homogeneous Energy Density with Negative Pressure.- à l'effet Casimir.- Casimir Effect and Geometry.- Measurement of the Atom-Wall Interaction: from London to Casimir¡ªPolder.- Recent Experiments on the Casimir Effect: Description and Analysis.- Dark Energy and the Destiny of the Universe.- II: The Renormalization.- An Introduction to Renormalization.- Exact Renormalization Group.- Phase Transitions and Renormalization Group: from Theory to Numbers.- Symétries galoisiennes et renormalisation.- The Anomalous Magnetic Moments of the Electron and the Muon.- Physics at the Large Hadron Collider.