The most renowned French specialists in their fields have contributed to this fourth volume in the series. The present collection sheds light on the major issues raised by cosmology, the solar system, the stars and the galaxies, the earth, the oceans and the climate, matter and its organisation, complexity, chemical transformations and the development of mathematics.With contributions from André Ambles, Alain Aspect, Jean Audouze, Roger Balian, Sébastien Balibar, Eva Bayer, Philippe Biane, Jean-Pierre Bibring, Michel Blay, Jean-Pierre Bourguignon, André Brahic, Édouard Brezin, Michel Campillo, Michel Cassé, Patrick Chaquin, Claude Cohen-Tannoudji, François Combes, Alain Connes, Thibault Damour, Stanislas Dehaene, Ivar Ekeland, Hubert Flocard, Uriel Frisch, Élisabeth Giacobino, Jean-Yves Girard, Henri Godfrin, Denis Gratias, Étienne Guyon, Serge Haroche, Yves Hellegouarch, Claude Jaupart, Thierry Juteau, Jean-Pierre Kahane, Patrick de Kepper, Étienne Klein, Marc Lachièze-Rey, Jean-Louis Le Mouel, Xavier Le Pichon, Christian Le Provost, Michel Lesieur, Hervé Le Treut, Jean-Pierre Lehn, Jacques Lewiner, Pierre-Louis Lions, Jean-Pierre Luminet, Jean-Paul Malrieu, Benoit Mandelbrot, Ghislain de Marsily, Jean-Louis Martin, Philippe Masson, Yves Meyer, Christian Minot, Jean-François Minster, André Neveux, Yves Petroff, Joel Picault, Marie Piléni, Michel Piécuch, Jim Ritter, Dimitri Rodichev, David Ruelle, Robert Sadourny, Olivier Talagrand, Catherine Thibault, Jacques Tits, Daniel Treille, Nguyen Trong Anh, François Vannucci, Sylvie Vauclair, Michel Verdaguer, Alfred Vidal-Madjar, Laurent Vigroux, Claude Weisbuch.