Published online by Cambridge University Press: 29 November 2013
Serious studies of materials are often serious studies of defects, for control of properties of materials implies control of defects or impurities. Understanding defect phenomena is crucial, and both theoretical ideas and modeling are enhancing key areas of materials properties and processing. I shall review some of the ways theory contributes. Theory enters into all aspects of materials science, even if you don't always realize you are using it.
Even self-styled practical people, for whom theory is a luxury, use theory routinely in its first main role, as a framework for the data they lovingly collect. Elasticity theory, electromagnetic theory, and thermodynamics are normal tools for working engineers. The simplest ideas about electronic and atomic structures of solids are now so standard that one can forget their original impact, just as one forgets those within living memory who objected even to the idea of atoms. It was theory which gave clear guidelines for solids to be metals or insulators, when the real-space ideas of crystal structures based on interacting atoms were complemented by the reciprocal space notions from band theory. Such rules had been far from obvious. The behavior of amorphous solids has forced analogous theory-led upheavals in understanding.