Symmetries In Nature: The Scientific Heritage Of Louis MichelReflecting the oeuvre of a man of two cultures: the culture of pure mathematics and the culture of theoretical physics (in the words of his long time friend and co author, Kameshwar Wali), this volume is centred around the notion of symmetry and its breaking. Starting with particle physics, the content proceeds to symmetries of matter, defects, and crystals. The mathematics of group extensions, non linear group action, critical orbits and phase