Solid foundations: structuring American solid state physics, 1939–1993

Abstract

When solid state physics formed in 1940s America, it was unusual. It violated the longstanding convention that physics should only be subdivided according to natural classes of research problems or consistent sets of techniques. Instead, solid state incorporated a wide range of concepts and methodological approaches that had only the most superficial similarities. The unifying force behind the field was the explicit professional goal of bringing academic and industrial researchers into closer dialogue. The non-traditional manner in which solid state formed was symptomatic of a sea change in the American physics community as some physicists in the 1940s began thinking about professional and institutional structures as tools with which they could actively define and maintain the scope and mission of physics. This shift had consequences both for solid state, and for American physics as a whole. Solid state was initially defined in terms of 1940s professional challenges, and so was forced to continually reimagine itself as the context changed around it. Eventually, it fractured into subgroups with divergent perspectives about the field’s goals and how best to address them. One of these, condensed matter physics, has typically been understood as a simple renaming of solid state physics. A close examination of the process by which condensed matter emerged, however, indicates that it represented an intentional return to defining a sub-disciplinary on the basis of natural phenomena and investigatory techniques. Condensed matter physics grew from pointed reactions against the segment of solid state that was closely aligned with industry. It crafted an identity that emphasized the intellectual puzzles physical studies of complex systems could address. As broadly conceived fields like solid state physics established themselves and grew, both in population and in influence, physics as a whole became a broader enterprise. Research areas that might otherwise have branched off into engineering or become independent specialties were offered a place in sub-disciplines like solid state physics. Additionally, other elements of the physics community adopted solid state’s mode of discipline formation, making the definition of “physics” more fluid and responsive to contemporary professional pressures. The evolution of solid state physics was guided throughout by a philosophical debate over the nature of fundamental knowledge. The disagreement persisted mostly between solid state physicists, who advocated the stance that fundamental knowledge could be found at any level of complexity, and high energy physicists, who restricted fundamental knowledge to the theories and concepts that governed the smallest constituents of matter and energy. The progress of this debate was driven by professional concerns about funding and intellectual prestige, and the philosophical positions physicists developed helped, in turn, to shape the field’s professional infrastructure.