French physicist. He was awarded the Nobel Prize for Physics in 1991 for his work on disordered systems including polymers and liquid crystals, and for the development of mathematical methods for studying the behaviour of molecules in a liquid on the verge of solidifying. He showed how mathematical models, developed for studying simpler systems, are applicable to such complicated systems.
It had been known for a long time that liquid crystals scatter light in an unusual way but all early explanations failed. De Gennes found the explanation in the special way that the molecules of a liquid crystal are arranged. According to de Gennes, the molecules are arranged in a similar way to the molecules of a magnet, so that they point in the same direction. De Gennes found similar analogies between the behaviour of molecules in magnetic materials and polymers. This led to the formulation of laws from which simple relations between different properties of polymers can be deduced. In this way, predictions can be made about unknown properties – predictions which have been confirmed by experiment.
De Gennes was born in Paris, France, and graduated from the Ecole Normalen in 1955. From 1955 to 1959 he was a research engineer at the Atomic Energy Centre at Saclay, working mainly on neutron scattering and magnetism. A brief period at Berkeley, California, and over two years in the French navy followed before he became assistant professor at Orsay. In 1971 he became professor at the College de France, Paris.