ArgumentThis 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. From Kujirai's group, Nishina Yoshio started his career and became the most important Japanese atomic and nuclear physicist of the 1930s. (shrink)

SummaryDuring the 1920s and 1930s, Italian physicists established strong relationships with scientists from other European countries and the United States. The career of Bruno Rossi, a leading personality in the study of cosmic rays and an Italian pioneer of this field of research, provides a prominent example of this kind of international cooperation. Physics underwent major changes during these turbulent years, and the traditional internationalism of physics assumed a more institutionalized character. Against this backdrop, Rossi's early work was crucial in (...) transforming the study of cosmic rays into a branch of modern physics. His friendly relationships with eminent scientists — notably Enrico Fermi, Walther Bothe, Werner Heisenberg, Hans Bethe, and Homi Bhabha — were instrumental both for the exchange of knowledge about experimental practices and theoretical discussions, and for attracting the attention of physicists such as Arthur Compton, Louis Leprince-Ringuet, Pierre Auger and Patrick Blackett to the problem of cosmic rays. Relying on material from different archives in Europe and the United States, this case study aims to provide a glimpse of the intersection between national and international dimensions during the 1930s, at a time when the study of cosmic rays was still very much in its infancy, strongly interlaced with nuclear physics, and full of uncertain, contradictory, and puzzling results. Nevertheless, as a source of high-energy particles it became a proving ground for testing the validity of the laws of quantum electrodynamics, and made a fundamental contribution to the origins of particle physics. (shrink)

By 1933, the class of generally accepted elementary particles comprised the electron, the photon, the proton as well as newcomers in the shape of the neutron, the positron, and the neutrino. During the following decade, a new and poorly understood particle, the mesotron or meson, was added to the list. By paying close attention to the names of these and other particles and to the sometimes controversial proposals of names, a novel perspective on this well-researched line of development is offered. (...) Part of the study investigates the circumstances around the coining of “positron” as an alternative to “positive electron.” Another and central part is concerned with the many names associated with the discovery of what in the late 1930s was generally called the “mesotron” but eventually became known as the “meson” and later again the muon and pion. The naming of particles in the period up to the early 1950s was more than just a matter of agreeing on convenient terms, it also reflected different conceptions of the particles and in some cases the uncertainty regarding their nature and relations to existing theories. Was the particle discovered in the cosmic rays the same as the one responsible for the nuclear forces? While two different names might just be synonymous referents, they might also refer to widely different conceptual images. (shrink)

In 1942, American Nobel Prize-winning physicist Arthur Compton pointed out that, “Because in this field of cosmic ray studies certain unique advantages are given by their geographical position, this field of physics has been especially emphasized in South America.” This paper seeks to interrogate the making of Latin America's uniqueness with respect to cosmic-ray research through an analysis that considers Compton's geographical argument, but also goes beyond it, referring to the interactions of nature, knowledge, practices, scientific communities, and diplomacy. To (...) begin with, it highlights the place-based strategies and practices associated with cosmic-ray research. Once research in the field at different altitudes demonstrated that cosmic rays traveled from outer space to the Earth surface, their nature was scrutinized by expeditions that covered broad vertical and horizontal expanses. The study of cosmic rays in Latin America displayed the mobilization of that strategy, which reinforced the reliability of certain sites located at high altitudes and close to the geomagnetic equator in projected investigations. Moreover, such analysis of cosmic rays involved research practices in the field, the emergence of (local, regional, or international) research traditions, and the creation of spaces of knowledge at different scales. By centering on the interaction of knowledge and place, this paper shows that an exploration of the “up-and-down journeys” of cosmic-ray research in Latin America expands our understanding of the geographies and practices of 20th-century physics. (shrink)