Collective behaviour

Abstract

At each change of length-sale in a material new science emerges. The reductionist approach focuses on the atomic and electronic length scales in the belief that a fundamental understanding can be achieved only at this smallest scale. It is blind to the emergence of science no less fundamental at larger length scales resulting from interactions between very large numbers of atoms and defects. While the atomic scale always remains important, a complete understanding of plastic deformation and fracture involves long-range interactions between defects described by the theory of elasticity. Even the mechanism of electronic conduction in a metal changes from ballistic transport at the nanoscale to the diffusive transport of Ohm’s law at the macroscale.