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A researcher in soft matter whose work combines theory and simulation to study the physics of glass and the formation of spatial structure in complex materials.^[ref] His historical and mathematical account of the replica trick explains why averaging a partition function differs from averaging its logarithm when disorder is frozen. It also identifies the ambiguity in the analytic continuation used by this method, helping readers understand both its usefulness for spin glass models and its mathematical limitations.^[ref]

Pierre-Gilles de Gennes developed connections between the physics of polymers and liquid crystals, using ideas from critical phenomenon studies. Long molecules and orientationally ordered fluids can have large collective responses even when their microscopic constituents differ greatly. Scaling and order-parameter descriptions identify which large-scale behavior follows from symmetry and connectivity rather than detailed molecular chemistry. His account of soft matter emphasizes this ability to move useful physical ideas between seemingly different materials, while retaining the experimental phenomena that distinguish them.^[ref]

A physicist who held the condensed matter physics chair at Collège de France from 1971 to 2004.^[ref]

Polymer physics connects the conformations and motion of long molecules to the properties of a material. A polymer can change shape through many segment rotations while its chemical backbone remains intact. This makes the competition between flow and relaxation important: the same chain can behave as a coil in one experiment and an extended object in another. Soft matter includes both these flexible structures and liquid crystals, whose orientational order produces a different route to strong mechanical and optical response.

Soft matter studies materials whose large-scale structures respond strongly to modest mechanical or thermal disturbances, including polymers, liquid crystals and colloids. Polymer physics connects chain conformations to material response; the coil-stretch transition is one example.

Soft matter physics studies the physical behaviour of soft matter, including its response to mechanical and thermal perturbations.