An Engineering Approach
Robert W. Batterman
Abstract
This chapter begins with a discussion of Julian Schwinger’s “engineering approach” to particle physics. Schwinger argued from a number of perspectives that the very theory (Quantum Electrodynamics, for which he won a Nobel prize) was inadequate. Further, he claimed that an intermediate theory between the fundamental and the phenomenological was superior. Such a theory focuses on a few parameters at intermediate or mesoscales that we employ to organize the world. Schwinger’s motivations were avowedly pragmatic, although he did offer nonpragmatic reasons for preferring such a mesoscale approach. This engineering approach fits well with the idea that the introduction of order parameters in condensed matter physics introduced a natural foliation of the world into microscopic, mesoscopic, and macroscopic levels. It further suggests that a middle-out approach to many-body systems is superior to a bottom-up reductionist approach. The chapter also discusses a middle out approach to multiscale modeling in biology.