“Why is the world that surrounds us so complex while the underlying laws of physics are simple?” This fundamental question has vast ramifications. Think of clouds in the sky, spraying waves of the oceans, or an ice rose formed on your window a winter morning: Although the water molecules are simple in shape and interact by simple forces, they can grow into amazingly complex patterns. This illustrates processes that are simple step by step, but when repeated, can result in complexity where; “the whole is different from the sum of its many parts” – much like architecture is different from the attributes of the individual building blocks, e.g., a brick, used to assemble a house.

Traditionally, science – and in particular physics, tries to simplify problems. For example, Newton's laws of motion are deterministic, i.e., we can predict the future of mechanical systems from knowing their present state. Thermodynamics uses ideas of equilibrium, where systems are in their most probable state determined from statistical mechanics. However, many systems and processes are known to exhibit non-equilibrium and non-stationary behaviour. Their dynamics can seem unpredictable, or have periods of apparent stability punctuated by sudden change, i.e., intermittent behaviour – all typical features of complex systems.

Complex matter science deals with condensed matter systems showing complex patterns of behaviour in a broad sense of the word. It aims to uncover the physical reasons for complexity, and capture the drama and richness caused by tiny variations and perturbations. During the past year at CAS, these have been the overall goals of our group, where the concrete work had strong links to experimental activities taking place in parallel at the physics departments of the University of Oslo, NTNU and IFE. Examples of systems we have studied are; granular matter, vortices and instabilities in superconducting materials, complex fluids, polymers, flow in porous media and quantum systems in complex environment.

Thus, the project has promoted synergy in several directions and at several levels. Of special
importance has been the added value created by bringing high-level scientists and their students from several institutions, nationally and internationally, together to work on selected topics in complex matter science, and thereby promoting Norway’s reputation as an attractive environment for scientific excellence and education.