Historians, philosophers, and physicists portray the 1920s and 1930s as a period of major theoretical breakthrough in physics, quantum mechanics, which led to the expansion of physics into the core of the atom and the growth and strengthening of the discipline. These important developments in scientific inquiry into the micro-world and light have turned historical attention away from other significant historical processes and from other equally important causes for the expansion of physics. World War II, on the other hand, is often seen as the watershed moment when physics achieved new levels of social and technical engagement at a truly industrial scale. Historians have shown that military interests and government funding have shaped physics to unprecedented degree, and according to some, to the extent of discontinuity with earlier practices of research (Forman 1987; Kevles 1990; Kaiser 2002). In this vein, Stuart Leslie wrote, “Nothing in the prewar experience fully prepared academic scientists and their institutions for the scale and scope of a wartime mobilization that would transform the university, industry, and the federal government and their mutual interrelationships” (Leslie 1993, 6). While one can never be fully ready for novelties, the contributors to this issue show that developments in interwar physics did prepare participants for their cold war interactions with industry and government.

This paper examines some of the ways that machines, mechanisms, and the new mechanics were treated in post-World War I discourse. Spengler's 1919 Decline of the West and Hessen's 1931 study of Newton have usually been tied closely to Weimar culture in Germany, and Soviet politics. Linking them also to the writings of Rathenau, Simmel, Chase, Mumford, Hayek, and others, as well as to Dada and film studies of the city will indicate central features of a wide-ranging, international discourse on the machine and mechanization. I argue that machines were so thoroughly integrated into social and economic experience that we can treat this as a distinctive new phase in the cultural history of mechanics, what some contemporaries called the “machine age”: a period in which rather than the hand mill or steam engine, the city stands as an appropriate realization (and sometimes symbol) of the significance but also ambiguities and tensions of mechanical life; and concepts of mechanization were extended to encompass the economy and market mechanisms.

This paper discusses one aspect of the context in which atomic physics developed in Japan between 1905 and 1931. It argues that during this period, there was a social context in which atomic physics was valued as a study of the electron and was thus relevant to electrical engineering. To demonstrate this, I first show that after the Russo-Japanese War, electrical engineering was deemed a valuable and viable field of research in Japan. Second, I show that physicists wrote textbooks and popular accounts about the electron, covering topics from both atomic physics and electrical engineering and presenting the former as relevant to the latter. Finally, as an example of how atomic physics partially emerged from this context, I discuss the group of Kujirai Tsunetarō, an electrical engineer who worked in the physics department of the Institute for Physical and Chemical Research (RIKEN). From Kujirai's group, Nishina Yoshio started his career and became the most important Japanese atomic and nuclear physicist of the 1930s.

Concentrating on the important developments of quantum physics, historians have overlooked other significant forces that shaped interwar physics, like that of technology. Based on the case of piezoelectricity, I argue that interests of users of technics (i.e. devices of methods) channeled research in physics into particular fields and questions relevant for industrial companies and governmental agencies. To recognize the effects of such social forces on physics, one needs to study the content of the scientific activity (both experimental and theoretical) of the researchers within its social and disciplinary contexts. By examining paths of individual scientists along with a study of the research in the field as a whole this paper exposes a range of reasons that led researchers to studies pertinent to technics. In particular, it shows that commercial, social, and military powers shaped interwar research through institutions aimed at fostering technology, some of them newly founded, and by a general view that academic research should help technology, a position that became more common at the time.

The discovery of electron diffraction by George Paget Thomson in Aberdeen and Clinton J. Davisson and Lester H. Germer at the Bell Labs has often been portrayed as an example of independent discovery. Neither team was particularly interested in the developments of the nascent quantum theory but they both ended up demonstrating one of the most striking experimental consequences of the new physics. This paper traces the aftermath of this discovery and the way electron diffraction immediately turned from empirical evidence of a highly novel theory into a technique for applied and technological research. Thomson was the first to design an “electron diffraction camera,” an instrument that soon found its place in laboratories around the world. I discuss the role played by Davisson and Germer, and by Thomson in the development of electron diffraction as a “research technology,” taking into account their specific institutional settings and research cultures. While Davisson and Germer remained in the industry-oriented Bell Labs, Thomson moved to Imperial College in 1930 where collaboration first, and competition later with George I. Finch was also relevant for the consolidation of an instrument that eventually became widely known as the “Finch Camera.”

During the interwar period research on turbulence met with interest from different areas: in aeronautical engineering turbulence became a subject of experimental study in wind tunnels; in naval architecture and hydraulic engineering turbulence research was on the agenda because of its role for skin friction; applied mathematicians and theoretical physicists struggled with the problem to determine the onset of turbulence from the fundamental hydrodynamic equations; experimental physicists developed techniques to measure the velocity fluctuations of turbulent flows. In this paper I describe the rise of turbulence in the 1920s and 1930s as a research field under the label of applied mechanics. Although the focus is on Germany, the international development of this research field is illuminated by the role which Ludwig Prandtl played as its acknowledged “chief” (G. I. Taylor). I argue that the multifaceted character of this research field calls for an epistemology and historiography which intrinsically takes the interaction of science and engineering into account.