Introduction
Around 6 o'clock in the morning of May 27, 1905, the battleship Mikasa, the flagship of the Japanese Imperial Navy's combined fleet moored in Jinhae Bay, received a telegraph message. The message originated from the Shinano Maru, a scouting ship of the fleet, saying that she had located Russia's Baltic fleet in Square 203. If it reached Vladivostok, the Baltic fleet could pose a threat to the supply line of the Japanese army, which was fighting hard battles on the continent. The message from the Shinano Maru and the following confirmation by the cruiser Izumi enabled Admiral Tōgō Heihachirō,Footnote 1 the commander of the Japanese fleet, to intercept the Baltic fleet and attack it with superior firepower. The ensuing Battle of the Japanese Sea ended in Japan's overwhelming victory, hastening the end of the war. Its outcome was largely determined when the wireless telegraph informed Tōgō of the location of the Baltic fleet (A. Yoshida Reference Yoshida1981; I. Kimura Reference Kimura2006; Ohno Reference Ohno2008). The wireless and submarine cable network enabled the transmission of this vital information. In particular, navy engineer Kimura Shunkichi (1866–1938) developed its essential part, the wireless device called Type 36,Footnote 2 for which he was praised after the war (Wakai and Takahashi Reference Wakai and Takahashi1994, 138; Takuji Okamoto Reference Okamoto2014, chap. 9).Footnote 3
Japan's victory over Russia and the important roles played by domestic military technology, such as Kimura's Type 36 wireless device and Shimose Masachika's gunpowder,Footnote 4 symbolized Japan's rise as a new colonial power equipped with modern technology. As Michael Adas writes, Russia's apparent defeat shook European confidence in its superiority over non-Europeans and its ability to maintain its hegemony over modern machines. According to Adas, “A nonwhite, non-European people had not only mastered Europe's science and technology, but had proved more than a match for a mighty, if somewhat backward, European empire” (Adas Reference Adas1989, 361). Modern machines could now be turned against Europeans, as subsequently demonstrated in World War I. In Japan, the story of the Russo-Japanese War, and the role that Kimura's wireless devices played in it, spread widely in the postwar nationalistic fervor, and Kimura's devices have been held up repeatedly as symbols of Japanese accomplishment since then.Footnote 5
The war also marked the beginning of Japan's interwar period, which ended with the Manchurian Incident in 1931 and the Marco Polo Bridge Incident in 1937. Since the Meiji Restoration, Japan's national goal had been to rise as an equal of Western powers. With this goal achieved, Japan had to seek new goals. The victory engendered national confidence, even megalomania. It affected politics, culture, and science in postwar Japan. Electrical engineering, which had won acclaim thanks to Kimura's contribution to the war, was changing Japan's urban infrastructure and landscape through electrification.
This article aims to place the development of physics in Japan in this socio-cultural environment. I argue that in this environment there developed a context in which atomic physics was valued as studies of the electron, hence as knowledge relevant to electrical engineering.
It is probably safe to say that outside Europe and North America, Japan was one of the first countries to begin conducting research in atomic physics. By the end of the 1920s, the Japanese physics community had already conducted research on atomic physics and had published some significant findings. Nagaoka Hantarō proposed his Saturnian atomic model at a meeting in Tokyo as early as 1903 (Itakura, Kimura, and Yagi Reference Itakura, Kimura and Yagi1973).Footnote 6 Theoretical physicists, such as Ishiwara Jun, turned their attention to quantum theory in the 1910s (Nisio Reference Nisio2011). Spectroscopists, such as Takamine Toshio and Hori Takeo, conducted experiments related to atomic physics from the 1910s to the 1920s (Fujioka Reference Fujioka1963 and Reference Fujioka1964; Gearhart Reference Gearhart2010). Nishikawa Shōji's work on X-ray spectroscopy and crystallography during the same period was also closely related to atomic physics (Nishikawa Sensei Kinenkai 1982). Nishina Yoshio, who originally trained in electrical engineering, switched to the field of atomic physics in the early 1920s. Kikuchi Seishi, who was under Nishikawa's guidance, carried out his experiments on electron diffraction patterns in 1928 (Kikuchi Kinen Jigyōkai Henshū Iinkai 1978).
Around the turn of the century, promoting a science as basic as atomic physics was not common in Japan, where emphasis was placed on engineering and industrial, medical, and military research. Japan did not have a long tradition of scientific research. Only in the second half of the nineteenth century did the Japanese government begin to establish national academic institutions modelled after the European style. Quickly adopting the contemporary trend toward engineering education, the Meiji government followed the models of polytechniques and Technische Hochschulen and established the Imperial College of Engineering in 1871.Footnote 7 Henry Dyer, a student of William Rankine at the University of Glasgow, served as the principal and directed engineering education, drawing partially on his experience in Glasgow and partially on later models, such as that of the Eidgenössische Polytechnische Schule in Zurich (Miyoshi Reference Miyoshi1989; Kita Reference Kita2007). After the foundation of the Imperial University in 1886, the Imperial College of Engineering became the School of Engineering of the Imperial University (Miyoshi Reference Miyoshi2012). From that point on, the School of Engineering continued to be larger than the School of Science. The first Japanese research institute outside a university was a medical research institute called the Institute for Contagious Disease, which was founded by Kitasato Shibasaburō in 1892. Most early research institutions were medical institutes, industrial and agricultural testing stations, or military research institutes (Muramatsu Reference Muramatsu2016; Sawai Reference Sawai2012).
How then could a basic scientific field such as atomic physics develop in this environment, where the value of knowledge seemed to be based on practical utility? If Japan had developed an autonomous academic tradition within which the pure pursuit of knowledge could be sustained, the development of atomic physics might have been a natural consequence of the academic interests of physicists. In the early twentieth century, however, physics research in Japan was not autonomous.Footnote 8
Regarding the development of nuclear physics in the 1930s, Hirosige Tetu provided a social explanation in his classical work, which was originally published in 1962.Footnote 9 Hirosige attempted to explain the development of nuclear physics in Japan through the potential aerological utilities of cosmic ray research, which enabled Nishina's group to gain financial support from the newly established Japan Society for the Promotion of Science (JSPS) (Hirosige Reference Hirosige1973). In the 1930s, the cosmic ray was one of the most important research tools in experimental nuclear physics, leading to important experimental results, including the discoveries of the positron and the muon. Nishina's group captured (but did not identify) positron tracks in their cosmic ray photographs. Later, the group also independently captured the muon and measured its mass, although this breakthrough came slightly after Carl Anderson and Seth Neddermeyer's work (Y. Nishina, Takeuchi, and Ichimiya Reference Nishina, Takeuchi and Ichimiya1937; Takeuchi Reference Takeuchi, Tamaki and Ezawa1991; Nishimura 2012 and 2010).Footnote 10
Although Hirosige's work certainly illuminates one aspect of the social background of nuclear physics in Japan, it is not the whole story. As I argue in a separate paper, the most definitive factor in the development of nuclear physics at RIKEN in the 1930s was its strong tie to the medical community through X-ray and radium research, which shared many similarities with Bohr's institute (Aaserud Reference Aaserud1990) and Lawrence's laboratory (Heilbron Reference Heilbron1990). In either case, it suffices to point out here that Hirosige did not give any account of the period before the 1930s. Nuclear physics did not suddenly appear in Japan in the 1930s. As mentioned, in the 1920s and even earlier, Japanese physicists were already working on atomic theory. The work of these Japanese physicists must have prepared those who contributed to nuclear physics in the 1930s.
To account for the gradual rise of atomic physics in Japan in the first three decades of the twentieth century, explanations other than Hirosige's are necessary. Because there were no external funding agencies in Japan, except for small private philanthropic organizations, funding did not directly determine research directions. In general, university professors lacked internal and external sources of research funding (Sakurai Reference Sakurai1940, 18). Physicists first had to gain public acceptance of their research in the hope that the government and private industries would be willing to support them in the future. At the same time, they needed to convince others and themselves of the value of their research. I aim to understand the value of atomic physics as it was perceived during the first three decades of the twentieth century.
Note that I use the word “value” and not “utility.” The latter can be one way in which values arise, but it tends to be conceived too narrowly. Certainly, in many contexts, although not all, utility is the only way in which things are valued. In basic sciences such as atomic physics, however, even when utility was considered, it was not actual utility but potential utility. Note also that my argument is not that atomic physics developed in Japan because of certain socio-cultural contexts. I do not make any causal deterministic claim; rather, I show that there was a relevant context that encouraged the development of atomic physics in Japan.
To demonstrate that there was a context in which atomic physics was valued because it was considered a theory of electrons and therefore relevant to electrical engineering, first, I briefly explore the cultural context after the Russo-Japanese War, where electrotechnical knowledge was considered valuable and worthy of investigation in Japan. Second, I examine the textbooks and popular accounts about the electron that physicists wrote under the rubric of “electron theory” (denshiron). These writings presented atomic physics as a theory of the electron, which was a valuable pursuit because of its relevance to electrical engineering. Finally, as an illustration of the interaction between electrical engineering and atomic physics, I present the case of a research group under Kujirai Tsunetarō, who worked on electrical engineering, including radio telephony, at Tokyo Imperial University and in the physics department at the Institute for Physical and Chemical Research (Rikagaku Kenkyūsho or RIKEN). Nishina Yoshio, probably the most important atomic and nuclear physicist in Japan after the period discussed here, started his career in this group at RIKEN.
Electrification and Wireless Technology in Japan
It might appear almost a matter of course that electrical engineering was perceived as valuable knowledge in the early twentieth century. Yet, it is still necessary to show in what ways it appeared so. In addition, it was far from self-evident that conducting research, instead of importing research results, was a wise decision in Japan at that time.
Kikkawa (Reference Kikkawa2004) explains how Japan's electrification progressed after the Russo-Japanese War. Soaring coal prices after the unprecedented naval battles induced Japanese electric companies to build long-distance networks to utilize waterpower, making electricity more affordable. Combined with the domestic manufacturing of metal-filament lamps, electric lighting became available to ordinary households, and its use eventually surpassed that of gas lamps. Cheap daytime electricity allowed the introduction of electric motors into factories (Kikkawa Reference Kikkawa2004, 26–62). Around the same time, electrification of transportation progressed in Japan. Electric streetcars replaced horsecars in cities, and electrified trains replaced steam locomotives in suburbs (Suzuki 2013, 182–200).
Originally less visible than the electrification of light, power, and transportation, electric communication became prominent during the war. As in other countries, the telegraph network was the first electric infrastructure, and it expanded with the railroad network. In modern nations, especially colonial empires, the electric telegraph was vital (Headrick Reference Headrick1991). As a country aspiring to be a new industrialized colonial power, Japan strived to establish a telegraph network in the Japanese homeland and its colonies (Wakai and Takahashi Reference Wakai and Takahashi1994; Yang Reference Yang2010; Ariyama Reference Ariyama2013). Research on wireless communication had already begun in Japan slightly before the turn of the century. Matsushiro Matsunosuke, an engineer at the Electrotechnical Laboratory (Denki Shikenjo) of the Ministry of Communication, successfully experimented on a wireless device using a Marconi-type coherer in 1897 (Dempa Kanri Iinkai 1951, 3:16). Kimura's Type 36 device and its role in the Russo-Japanese War augmented the values of electrotechnical knowledge.Footnote 11 Seizing the opportunity, Kimura immediately published a war-commemorative edition of a popular account of wireless technology Sekai no musen denshin (Wireless Telegraphy in the World), with a foreword by Commander Akiyama Saneyuki, the naval strategist and principal planner of Japan's combined fleet during the war (S. Kimura Reference Kimura1905).
Following Kimura's lead, Torikata Wichi (1883–1923) made ground-breaking contributions to wireless engineering. Torikata graduated from the Department of Electrical Engineering at Tokyo Imperial University in 1906. He then worked at the Electrotechnical Laboratory of the Ministry of Communication, developing in 1908 a new kind of detector, which he called the kōseki (ore) detector (Torikata Reference Torikata1908). It was the Japanese counterpart of Greenleaf W. Pickard's crystal (or cat's whisker) detector in 1906. Torikata's detector proved extremely sensitive and greatly extended the range of wireless communication (Dempa Kanri Iinkai 1951).
Furthermore, Torikata pioneered the early technology of wireless telephony. In 1912, with Yokoyama Eitarō and Kitamura Masajirō, Torikata devised a new wireless transmitter. They named it the “TYK device” after their initials (Torikata Reference Torikata1914). To generate continuous high frequency oscillation, Torikata and his collaborators used a spark gap that adjusted automatically to sustain continuous oscillations (Torikata, Yokoyama, and Kitamura Reference Torikata, Yokoyama and Kitamura1912a, Reference Torikata, Yokoyama and Kitamura1912b). It was one of the most successful wireless telephones before the advent of vacuum tubes. In 1914, Torikata and others successfully tested their invention in the field between the small islands in Ise Bay, demonstrating its practical utility (Torikata Reference Torikata1915).
Torikata's invention quickly became outdated as vacuum tubes suitable for practical use appeared. Torikata and other Japanese engineers at the Ministry of Communication's Electrotechnical Laboratory started research on vacuum tubes in 1915, and the TYK wireless systems began to be replaced in 1917 (Dempa Kanri Iinkai 1951, 3:33). Yet, his achievement was a rare success, demonstrating again that Japanese electrical engineering could produce something like the TYK device, which could compete with European or American devices, although for a short period of time. In many areas of research, Japanese policy makers and senior scientists were not certain whether they should import foreign technology or invest in domestic research infrastructure (Bartholomew Reference Bartholomew1989). In addition to its national and military values, wireless engineering proved to be a research field worthy of investment.
Thus, after the Russo-Japanese War, Japanese people, especially city-dwellers, watched electrical engineering visibly change their material environments and enhance their quality of life after the war. They had been going through the same process that Graeme Goody described as the “domestication of electricity” (Gooday Reference Gooday2008, 1). In this new material environment, Japanese people pursued knowledge of electricity. Various popular accounts of electricity helped them advance in that process. For example, writings of authors like Charles R. Gibson – such as Romance of Electricity, The Autobiography of an Electron, and Wireless Telegraphy and Telephony without Wires (Gibson Reference Gibson1906, Reference Gibson1911, and Reference Gibson1914) – were translated into Japanese. None other than Torikata wrote a foreword to the Japanese translation of Wireless Telegraphy and Telephony without Wires, emphasizing the importance of popularizing scientific knowledge (Gibson Reference Gibson and Sekizawa1915).Footnote 12
The material cultures, the use of wireless technology in war, and the relative success in wireless research strongly suggest that there was indeed a social context in Japan in which electrical engineering was valued. Moreover, electrotechnical knowledge, particularly radio technology, appeared to be vital to empire building and feasible by Japanese engineers.
Electron Theory in Japan
The value of electrical engineering by itself does not warrant the value of physics. For the latter to be considered worthy of domestic research, something else had to happen. In this section, I show that the electron did that. I argue that physicists presented atomic physics as a theory of the electron and claimed the importance of the electron in understanding electricity and electrical engineering through their textbooks and popular writings. Because such writings were received well, we can conclude that there was a social context in Japan in which atomic physics was valued as a theory of the electron and as relevant to electrical engineering.
In Japan, as in other countries, electrical engineering was closely tied to physics from the beginning. Some leading figures in electrical engineering were originally trained in physics. William E. Ayrton (1847–1908), who founded electrical engineering in Japan, was originally a student of William Thomson. His official title in Japan was professor of telegraphy and physics (denshin oyobi rigaku kyōshi) at the Imperial College of Engineering, where he provided rigorous education in introductory physics (Ōkurashō 1889, 979; Gooday Reference Gooday, Matthew and Harrison2004; Uemura Reference Uemura2014). Namba Tadashi (1859–1920), who became a professor of electrical engineering at Kyoto Imperial University in 1898 and the seventh president of the Institute of Electrical Engineers of Japan in 1918, was originally a graduate of the French Department of Physics at Tokyo Kaisei Gakkō.Footnote 13 Kimura, the inventor of the Type 36 wireless device, graduated from the Department of Physics at Imperial University in 1888. After some teaching, he went to the United States, studied at Harvard and Yale under James M. Peirce and Josiah Willard Gibbs, and received a Ph.D. with his dissertation on general spherical functions. After his return home, he became a professor at the Second Higher SchoolFootnote 14 in Sendai in 1896 and shifted his interest to wireless engineering (Takuji Okamoto Reference Okamoto2014, chaps. 6–9).
Nagaoka Hantarō (1865–1950) was the leading physicist both in theory and in experimentation during the first three decades of the twentieth century, and much of his research was closely tied to electricity and the electron.Footnote 15 He graduated from the Department of Physics of Imperial University in 1887, to which he returned as a professor after studying physics in Europe under Ludwig Boltzmann and others. One of Nagaoka's best-known achievements, the Nagaoka coefficients, was more in the domain of electrical engineering than physics. It was a convenient way to calculate inductance of a solenoid. If the coil is sufficiently long, its inductance can be calculated by a simple formula. If it is finite, however, the calculation involves elliptic integrals. Nagaoka devised a convenient way to simplify this calculation by tabulating coefficients that depend on the diameter to the length ratio of the coil. The formula for an infinitely long solenoid multiplied by this coefficient gives an accurate numerical value of the inductance (H. Nagaoka Reference Nagaoka1909). This method was publicized internationally through the revised edition of Edward B. Rosa and Frederick W. Grover's Formulas and Tables for the Calculation of Mutual and Self-Inductance (Reference Rosa and Grover1912) (see Itakura, Kimura, and Yagi Reference Itakura, Kimura and Yagi1973, 356–60).
These early examples show that training in physics could be relevant to electrical engineering. In the interwar period, however, electrical engineering was already an established discipline, capable of producing future practitioners and researchers on its own. Positions of electrical engineering at specialized departments of prestigious schools were generally occupied by those who held degrees in engineering. For example, at Tokyo Imperial University around 1906, all four professors in electrical engineering had a doctorate in engineering. The assistant professor and the two lecturers held a bachelor's degree in engineering. In fact, among the approximately seventy faculty members of the School of Engineering, only two held a bachelor's degree in science, and none held a doctorate in science (Tokyo Teikoku Daigaku 1907, 185–91). Graduates from science departments taught engineering students, but their roles were mostly limited to introductory physics. At the First Higher School, for example, among more than seventy faculty members and adjunct teachers, only one adjunct teacher was a doctor and bachelor in engineering, whereas the principal of the school held a doctorate, and five others held a bachelor's degree in science (Daiichi Kōtōgakkō 1907, 101–8). Science teachers at such schools taught electromagnetism and supervised student experiments for those who intended to advance to schools of science, engineering, medicine, or agriculture at imperial universities. This experience broadened the perspectives of science graduates. Kimura's interest in wireless started during his years at the Second Higher School (Takuji Okamoto Reference Okamoto2014, 83–84). As I discuss later, Mizuno Toshinojō, who taught at the Third Higher School, probably had a similar experience.
The electron provided physicists with an opportunity to regain the relevance of their research to electrical engineering. When the idea of the electron was introduced into Japan, it was physicists who claimed intellectual authority over it. In Japanese language publications, according to Ariga (Reference Ariga2013), denshi, the Japanese term for “electron,” first appeared in a partial translation of Oliver Lodge's public lecture “Electricity and Matter” (Lodge Reference Lodge1903a) by Aichi Keiichi (1880–1923) and Nagaoka's foreword to it (Lodge Reference Lodge and Aichi1903b). Aichi was a theoretical physicist at Tohoku Imperial University, who worked on various mathematical physical themes. His works were generally calculation intensive, often using advanced mathematics in various topics, including electromagnetism, hydrodynamics, optics, and mechanics. I have previously described Aichi as a typical theoretical physicist in Japan before the advent of quantum physics (Ito Reference Ito2002, chap. 2).
By then, Japanese physicists had already started conducting research related to the electron. I mentioned the Saturnian model of the atom by Nagaoka (H. Nagaoka Reference Nagaoka1904). Nagaoka's Saturnian model of the atom required detailed theoretical investigations of the motions of electrons to demonstrate the dynamic stability of the proposed model. He used the term “electron” explicitly.Footnote 16 Thereafter, he attempted to derive various properties of the atom from his model, including spectra, radioactivity, and the Joule-Thomson effect (H. Nagaoka Reference Nagaoka1905a, Reference Nagaoka1905b, and Reference Nagaoka1905c). Another example was Sano Shizuwo's study of thermoelectricity in 1907 (Sano Reference Sano1907).
The term denshiron first appeared in 1906. In Japanese, ron means “theory” or “discourse.” Hence, denshiron can be narrowly defined as a formal theory of the electron, but it can also mean “discourse on the electron.” The word was used loosely, and its meaning changed over time. The term was convenient for Japanese physicists because it allowed them not only to present it as the forefront of physics but also as a body of knowledge with practical values that could contribute to electrical engineering by revealing the true nature of electricity. Using denshiron, physicists were able to work on this academically important topic and claim its value for electrical engineering.
In the early years, denshiron was often used to refer to theories of the electron by Hendrik A. Lorentz, Joseph Larmor, Max Abraham, and others. In April 1906, in his semi-popular book, Rajiumu to denki busshitsu kan (Radium and Electrical Views on Matter), Nagaoka described electron theory and its potential applications. In the preface, he wrote that the current progress of physics was spurred on by efforts to solve the problem of matter and the problem of electricity in a unified way, and this set of problems originated from the discovery of radioactivity and developments in electron theory. After presenting recent developments in studies of radioactivity, Nagaoka outlined the “electrical views on matter” by William Crookes, Lorentz, J. J. Thomson, and others and described Walter Kauffman's experiment on the inertial mass of the electron, which appeared to refute Lorentz and support Abraham's electron theory.Footnote 17 Chapter sixteen of this book was entitled “Phenomena that should be explained by electron theory.” Among such phenomena, Nagaoka included electric current, relation between heat and electric conductivities, relation between electrolysis and ratio of heat and electric conductivities, thermoelectric current, absorption, and emission of radiation (H. Nagaoka Reference Nagaoka1906). This shows that Nagaoka was convinced that electron theory would clarify various phenomena related to electricity. These phenomena were also important to electrical engineering.
In the same year, another physicist started writing about denshiron. The theoretical physicist Kuwaki Ayao (1878–1945) was a student of Nagaoka's. He graduated from the Department of Physics at Tokyo Imperial University in 1899.Footnote 18 He later became a professor of physics at Kyushu Imperial University's School of Science and Engineering. Kuwaki was more interested in foundational and philosophical issues than in solving specific problems. During his career, he never published a scientific research paper on physics. Later, Kuwaki completely turned to the philosophy and history of science, becoming the first president of the History of Science Society of Japan in 1941. Apparently motivated by his interest in foundational issues, Kuwaki wrote an article that mentioned electron theory in 1906. It was entitled “Zettai undōron” (“On the absolute motion”) (Kuwaki Reference Kuwaki1906). The article consisted of a critical discussion of the notion of absolute motion since Newton and Leibnitz through Kant, Mach, and Boltzmann to contemporary issues, such as aether and electron theory (Kuwaki Reference Kuwaki1921; Tanaka Reference Tanaka1995; Abiko Reference Abiko2006). In the following year, Kuwaki's article “Denshi no keijō ni tsuite” (“On the shape of the electron”) further elaborated electron theory (1907). He explained three theories of the shape of the electron by Lorentz, Abraham, and Albrecht Bucherer. He also discussed experiments by Kaufman and discussions that took place at the German Physical Society and Gesellschaft Deutscher Naturforscher und Ärzte meeting in Stuttgart in September 1906, where most attendants supported Abraham's theory rather than those of Lorentz and Einstein (Kragh Reference Kragh1999, 111; Staley Reference Staley2008, 247–48). For Kuwaki, therefore, electron theory concerned fundamental questions about physics rather than electrical engineering, and his study arose from his interest in philosophical questions about relative and absolute motion.Footnote 19
Thereafter, the genre of denshiron thrived in Japan in textbooks and popular writings while its content gradually changed as atomic physics developed. Various recent developments in physics – including electromagnetism, relativity theory, spectroscopy, X-ray, radioactivity, light quanta, and atomic physics – were related to denshiron. In addition, new kinds of knowledge were able to explain familiar natural electric phenomena and recent electrotechnical artefacts.
In 1913, Kuwaki and Nagaoka published a translation of Lorentz's two-volume Lehrbuch der Physik (Lorentz Reference Lorentz1906-Reference Lorentz1907) into Japanese. While Lorentz's full-fledged exposition of his electron theory appeared in his lectures at Columbia University in March and April 1906 (published in 1909),Footnote 20 the electron appears throughout the second half of Volume Two of this textbook. In particular, the last, eighteenth chapter is entitled “Erscheinungen, welche durch die Elektronentheorie erklärt werden können (Phenomena that can be explained by electron theory),” gives theoretical discussions of various phenomena – including radioactivity, conduction of electricity, discharge phenomena, and the Zeeman effect – using Lorentz's electron theory (Lorentz Reference Lorentz, Nagaoka and Kuwaki1913; Ariga Reference Ariga2013).
Japanese physicists also started to write their own textbooks on electron theory. In the previous year, the physicist Mizuno Toshinojō (1862–1944) published a textbook called Denshiron (Electron Theory).Footnote 21 Mizuno was a professor of physics at Kyoto Imperial University. He graduated from the Department of Physics at Imperial University in 1890, and after working at higher middle schools, he became an assistant professor of the newly founded Kyoto Imperial University in 1898. He was one of the first to report Wilhelm Röntgen's experiment on the X-ray and to replicate it in Japan in 1896 (Imaichi and Hara Reference Imaichi and Hara1950). He was also heavily involved in wireless telegraphy, and he constructed his own devices. In 1904, he published a short book entitled Dempa to musen denshin (Electric Waves and Wireless Telegraphy). This book, starting with basic electromagnetic theory, explained recent advancements in wireless technology, including the wireless devices of William Henry Preece, Guglielmo Marconi, Adolf Slaby, Georg von Arco, Ferdinand Braun, Oliver Lodge, and Alexander Muirhead, Wilhelm Schloemilch, Lee de Forest, Reginald A. Fessenden, and Mizuno himself (Mizuno Reference Mizuno1904). Around 1907, Mizuno challenged Kimura to a competition over their wireless systems and lost. According to Kimura, Mizuno's device was based on Schloemilch's method of electrolysis (S. Kimura Reference Kimura1945, 95). He became interested in wireless telephony as well. In 1911, he published a textbook entitled Musen denshin denwa ron (Theory of Wireless Telegraphy and Telephony) (Mizuno Reference Mizuno1911).
Mizuno's Denshiron emerged out of an educational context. According to the preface, the book was based on his lectures at Kyoto Imperial University from 1911 to 1912. Written in the style of a textbook, the book covered a wide range of topics on phenomena and theories related to the electron. Most of the topics included in the book concerned physics: electric discharge, cathode rays, motions of electrons in electromagnetic fields, measurement of the mass to charge ratio of an electron, the Zeeman effect, thermal electrons, aether, blackbody radiation, Doppler effects, canal rays, Thomson's mass spectrometer, colloids, Brownian motions, conduction of electricity in metals, Joule's law, the Wiedemann-Franz law, X-rays, atomic models by Thomson, Nagaoka, and Nicholson, spectral lines, radioactivity, the photo-electric effect, energy quanta, light quanta, ionization, the Michelson-Morley experiment, relativity theory, and the shape of the electron. Many of these topics were highly relevant to electrical engineering and presented as such. In addition, the book included topics primarily concerned with electrical engineering, such as carbon electric arcs and Ohm's law (Mizuno Reference Mizuno1912; Ito Reference Ito2018).
Although Mizuno's book had the appearance of a textbook, its targeted readership was not just physics students. Maruzen, the publisher of Mizuno's book, marketed it to both physics students and a general audience. An advertisement for Denshiron said the following: “As the preface says, this book aims to outline the recent radical advancements in studies of electricity and illustrate activities of the electron in the material world. It is an incomparably novel book, full of curious materials. Not only those who aspire to learn science, but also students in engineering, medicine, and the humanities should immediately read this book” (Mizuno Reference Mizuno1918). Mizuno's book apparently attracted many readers. I have found the first to the sixth printing of this book, the last being published in 1923 (the content was not updated much). Mizuno also published textbooks on atomic physics – such as Genshiron (Theory of the Atom) in 1914 and Zoku genshiron (Theory of the Atom, Part II) in 1916 – and on relativity theory, Sōtai genritsu (Principles of Relativity) in 1922, although they were not as popular as Denshiron.
The success of Mizuno's textbook was partially due to his dramatic and flowery prose. Written in the pseudo-classical style of Meiji intellectuals, who were well versed in the Chinese classics, Mizuno's textbook was an amalgam of physical concepts, mathematical formulae, diagrams, and literary expressions, which even humanities students in that era might enjoy reading. In particular, the introduction and the concluding chapter celebrated the historical significance of the breakthroughs made by electron theory and the importance of electrons using poetic expressions that were underscored by many military metaphors. The “impregnable fortress” of the atom, once considered the ultimate basis of matter, had fallen to “three-sided attacks” by “heroes” (gōketsu), such as Lorentz, J. J. Thomson, and Marie Curie; “indeed, the discovery of the electron is a great victory in the war of physics” (Mizuno Reference Mizuno1912, 323–24). More importantly, Mizuno stressed the many roles played by electrons in natural phenomena. He wrote, “Electron! Electron! Its body is miniscule, yet it is omnipresent in the entire world” (ibid., 325). He praised the electron as “the atom of the atom,” “the overlord of the natural world, active everywhere” (ibid., 334). Such rhetorical devices stressing the historical significance of electron theory and the ubiquity of the electron in natural and artificial worlds were to be repeated in subsequent popular writings on electron theory. By emphasizing the importance of the electron, authors like Mizuno presented physics about the electron, namely atomic physics, as important and valuable.
Mizuno's textbook was not the only one on electron theory published in Japan around that time. In 1928, Saegusa Hikoo (1890–1948) wrote another textbook entitled Denshiron (Electron Theory). Saegusa had been a professor of physics at Tohoku Imperial University since 1926, and he graduated from the department of physics of the same university in 1915. He conducted research on topics closely related to electrical engineering. For example, he developed theoretical studies of the spark discharge on the surface of a dielectric (Saegusa Reference Saegusa1920). He conducted extensive experimental studies on the temperature dependence of dielectrics' conductivity (Saegusa Reference Saegusa1924) and attempted a theoretical explanation using Richardson's theory of thermionic electrons and other theoretical tools (Saegusa Reference Saegusa1926). In his book on electron theory, he wrote, “Electron theory was developed by Larmor and Abraham and completed by Lorentz” (Saegusa Reference Saegusa1928, 1). Saegusa discussed the kinematics of a single electron (Lorentz's theory and the photo-electric effect) and many electrons (electric conductivity) in addition to the atomic models of Ernest Rutherford and Niels Bohr (Saegusa Reference Saegusa1928).
The contemporary physicists wrote extensively about the electron in the genre of popular science. In addition to the semi-popular book mentioned above, Nagaoka wrote in 1912 a book entitled Genkon no denkigaku (Today's Studies of Electricity). This was a popular account of electromagnetic theory and electrical engineering at that time. In the last chapter, entitled “The Great Revolutionary Era in Science,” Nagaoka praised Lorentz as the leading figure in this revolution. He added Einstein's relativity theory, explaining that it was based on Lorentz's theory (H. Nagaoka Reference Nagaoka1912).
Mizuno also wrote popular accounts. One example is his Denshi no katsudō (The Activities of Electrons). Starting with the basic concepts of the electron and the atom, this book covers several topics, such as electric discharge, sparks, lightning, X-rays, radioactivity, motions of free electrons, arc lamps, wireless telegraphy, spectral lines, and chemical reactions. Both arc lamps and chemical reactions were relevant to wireless devices. As mentioned above, he developed a wireless detector based on electrolysis. Compared with Denshiron, this book was much shorter, and a larger portion was devoted less to theories than to specific examples of the “activities of electrons,” including electrotechnical devices. This book states clearly the relevance of electrons in wireless technology and to national interests, in a way we today might deem a “linear model.” The preface states, “The path toward the “Rich Nation, Strong Army” lies in the application of science. The application of science requires a solid foundation of science. To aim for applications with no regard to their basis is like drawing water downstream without tasting it at its source” (Mizuno Reference Mizuno1918, Preface). Such a claim for the importance of a scientific foundation also justifies physicists' research in electron theory.
Another popular account of the electron emphasized the importance of the electron to the extent of giving it a narrative identity. As mentioned previously, Aichi Keiichi was a theoretical physicist, and he was the first to use the Japanese term denshi (electron) in 1904. In 1923, soon after his premature death by food poisoning, Aichi's book, entitled Denshi no jijoden (The Autobiography of an Electron) (Reference Aichi1923), was published. It was an account of electrical phenomena narrated by an electron. Using the somewhat self-important first-person singular, wagahai, this book was written in the style of Natsume Sōseki's classical novel, I Am a Cat. Although Aichi failed to mention it, his book was a loose adaptation of Charles Gibson's The Autobiography of an Electron (Gibson Reference Gibson1911).Footnote 22
Although physicists wrote popular accounts on the electron, not all of them did research on it. Kuwaki did not really do any research in physics at all. Aichi never chose the electron as a subject of his research. Mizuno's primary concern was electromagnetic waves. Some, however, did research on the electron. In addition to Nagaoka, Sano, and Saegusa as mentioned above, there was another physicist in Saegusa's generation. Kikuchi Taiji (1893–1921) was the second son and heir of Baron Kikuchi Dairoku (1855–1917) and the older brother of Kikuchi Seishi. In 1919, he became an associate researcher (kenkyūin ho) at RIKEN and travelled to the United Kingdom to study recent developments in physics. Nagaoka, who married one of Dairoku's daughters, had high expectations for Taiji and wrote a very strong letter of recommendation for him to Ernest Rutherford.Footnote 23 In September, Kikuchi arrived in Cambridge to work with Rutherford and Francis William Aston, but, to Nagaoka's great lament,Footnote 24 he died there in 1921. Presumably, Rutherford himself wrote an obituary (E. R. 1921). Thus, Kikuchi Taiji is mostly known as a promising experimental physicist who died too young. It is less known that before RIKEN, he was in Torikata Wichi's group. After graduating from the Department of Experimental Physics in Tokyo Imperial University in 1917, he worked at the Electrotechnical Laboratory and conducted research on vacuum tubes under Torikata. As mentioned previously, Torikata's group at the Electrotechnical Laboratory started research on vacuum tubes in the mid-1910s. One electrical engineer in his group developed a theory of Irvin Langmuir's pliotron based on Langmuir's theory of space charge (Sadachi Reference Sadachi1917). Drawing on the work of Louis Alan Hazeltine, Kikuchi further discussed the pliotron as an oscillator (Kikuchi Reference Kikuchi1919). He also studied Albert Hull's dynatron, showing how it could be used as a frequency transformer (Kikuchi Reference Kikuchi1918).
In the 1920s, when Einstein's relativity theory became accepted in Japan, less attention was paid to the electron theories of Lorentz and Abraham, and many Japanese physicists shifted their attention to quantum theory. Some physicists, however, adamantly pursued theoretical investigations of electrons along the line of theories by Lorentz or Abraham, neglecting other developments. One young physicist, Doi Uzumi (1895–1945), even challenged Einstein's relativity theory from the viewpoint of electron theory. He was a theoretical physicist and a student of Nagaoka's. In September 1922, immediately before Einstein's visit to Japan in November, he published a book entitled Ainsutain sōtaiseiriron no hitei (Refutation of Einstein's Relativity Theory). Although the book attacked the relativity theory, the main content of the book was about electron theory, with four out of the six chapters of the book devoted to theoretical studies on electrons. For example, the first chapter was entitled “The Fundamental Equations of Electrons,” which discussed Lorentz's theory of electrons (Doi Reference Doi1922, 6).Footnote 25
As late as the 1930s and 1940s, one Japanese physicist and engineer attempted to achieve a breakthrough by developing a theory on the structure of the electron. Kakinuma Usaku graduated from the Department of Electrical Engineering at Tokyo Imperial University in 1914. Like Nishina Yoshio (Ito Reference Ito2002), he studied electrical engineering theory of three-phase systems under Hō Hidetarō’s supervision (Kakinuma Reference Kakinuma1914). From the late 1920s, he started publishing articles on the structure of the electron in the Proceedings of the Physico-Mathematical Society of Japan (Kakinuma Reference Kakinuma1928, Reference Kakinuma1929, Reference Kakinuma1930a, Reference Kakinuma1930b and Reference Kakinuma1931). It seems he was trying to build a classical unified field theory, but mainstream Japanese physicists were dismissive of Kakinuma's theory.Footnote 26 His obsession shows how important electron theory could be to a researcher who turned from electrical engineering to physics.Footnote 27
Electron theory by Japanese physicists at this point did not produce any immediately useful results for electrical engineering. Still, as long as physicists maintained intellectual authority over studies of the electron, electrical engineers turned to physicists for expert knowledge on the electron. Some of the electrical phenomena involving electrons appeared to require further investigation into the nature of the electron. Throughout the 1920s, electrical engineers expressed their hopes that electron theory would solve some of their problems, such as the issues related to electric discharge and lightning (Tadasu Okamoto Reference Okamoto1921; H. Yagi Reference Yagi1923; Yamamoto Reference Yamamoto1929; Ogawa Reference Ogawa1928).
Electrical engineers invited atomic physicists – such as Nagaoka, Shimizu Takeo, and Nishina – to give lectures for them. Such lectures took place in the Nakano Hatsune memorial lecture series, which commemorated Nakano Hatsune, an early professor of electrical engineering at Tokyo Imperial University and one of the founders and the third president of the Institute of Electrical Engineers of Japan. Nagaoka was invited twice, giving a talk first on relativity theory and then on quantum theory (H. Nagaoka Reference Nagaoka1922 and Reference Nagaoka1924). Nishina gave a talk on conceptual problems of quantum mechanics and Niels Bohr's institute (Y. Nishina Reference Nishina1929).
Among others, the lecture by Shimizu Takeo (1890–1976) in 1928, entitled “On the History and Recent Advancement of Electron Theory,” shows how the term electron theory (denshiron) was used by an atomic physicist in front of the audience of electrical engineers. Denshiron was beginning to be used to refer to quantum mechanical electron theory or to Dirac's theory of electrons. Shimizu was a nuclear physicist who graduated from the Department of Experimental Physics at Tokyo Imperial University in 1914.Footnote 28 He studied in Britain and the United States. In particular, he contributed to the development of the Wilson cloud chamber while he was working with Rutherford in the Cavendish Laboratory (Shimizu Reference Shimizu1922). In 1926, he succeeded to Nagaoka's chair of Theoretical Physics at Tokyo Imperial University.Footnote 29 In his 1928 lecture, he distinguished three periods in the history of electron theory: the Lorentz period, the Bohr period, and the Heisenberg Schrödinger period. The lecture was mainly devoted to the third period, giving a brief introduction to wave mechanics (Shimizu Reference Shimizu1928). Thus, Shimizu tied electron theory with quantum mechanics, presenting it as relevant to electrical engineering.
Shimizu was not alone in introducing quantum mechanics into electron theory. As mentioned earlier, Saegusa Hikoo's textbook on denshiron in 1928 was entirely based on classical physics. In 1931, he published a sequel entitled Shin denshiron (New Electron Theory). Topics in this textbook were taken from recent developments in quantum physics, including Fermi-Dirac statistics, wave and matrix mechanics and relativistic equations for electrons (Saegusa Reference Saegusa1931).
After the birth of quantum mechanics, the electron became a primary object of its equations. Japanese quantum physicists naturally treated the electron. The first Japanese theorist who contributed to the development of quantum mechanics was Sugiura Yoshikatsu (1895–1960). He is best known for his contribution to the quantum mechanical calculation of the hydrogen molecule. After the publication of Heitler and London's introduction of the idea of forces deriving from electron exchange to explain the binding force of hydrogen molecules, Sugiura carried out the calculation of the exchange integral and derived the actual theoretical values of the binding energy (Sugiura Reference Sugiura1927; Park Reference Park2009). Nishina, together with Oskar Klein, derived the formula for Compton (electron-photon) scattering from Dirac's relativistic theory of the electron (Klein and Nishina Reference Klein and Nishina1929; Yazaki Reference Yazaki2017). After Nishina's return to Japan in 1928, the task of making calculations related to the electron continued to occupy theorists of Nishina's group (Y. Nishina and Tomonaga Reference Nishina and Tomonaga1934; Y. Nishina, Tomonaga, and Sakata Reference Nishina, Tomonaga and Sakata1934; Y. Nishina, Tomonaga, and Tamaki Reference Nishina, Tomonaga and Tamaki1934; Y. Nishina, Tomonaga, and Kobayasi Reference Nishina, Tomonaga and Kobayasi1935).
The formulation and the developments of quantum mechanics made atomic physics appear even more relevant to electrical engineering. Quantum mechanics enabled calculations of properties of electrons and their effects in various cases. In the 1930s, however, electrical engineers started to claim their dominion over at least some of the studies on the electron. With the advent of vacuum tubes, the electron became so crucial for electrical engineering that electrical engineers began to include research on the electron within their discipline. As quantum mechanics became largely complete and theoretical physicists moved toward the questions of nuclear physics, electrical engineers began to notice that in order to solve the problems that they faced, they did not need expertise in the forefront of nuclear physics. By then, physicists had already amassed a considerable amount of knowledge on the electron, and it was up to engineers to make it useful for their own purposes. New generations of electrical engineers were ready to face the task.
This meant emergence of a new subdiscipline within electrical engineering. According to the Oxford English Dictionary, the word ‘electronics’ first appeared in 1910, but the term became popularized in 1930 with the publication of a new magazine, Electronics, from McGraw-Hill. In German, the term Elektronik already appeared in the first volume of Johannes Stark's Jahrbuch der Elektronik und Radioaktivität in 1904. In the early 1920s, there was no Japanese term for this word, but the English word and the idea had already been imported. Hoshiai Masaharu (1898–1986) was a pioneer in electronics in Japan and an author of early textbooks on electronics. When he graduated from the Department of Electrical Engineering at Tokyo Imperial University in 1922, he was immediately appointed as lecturer (kōshi) there. Hō Hidetarō, the most senior professor of the department, advised this new faculty member to work on electronics because there would be a great demand for the application of electronics in industry. Hoshiai readily followed this advice and became a specialist in electron tubes (Hoshiai Masaharu Sensei Tsuitō Kinenkai 1988, 12). The Japanese term denshi kōgaku (literally “electron engineering”) appeared in print in 1931 with the publication of Denshi kōgaku no riron to ōyō (Theory and application of electronics) (Denkigakkai 1931).
The word denshi kōgaku gained traction in the mid-1930s with the publication of several textbooks on this subject. Hoshiai wrote one of the earliest textbooks on denshi kōgaku with Honda Kanji (1899–1974). Honda is another researcher who represents close interactions between physics and electrical engineering at that time (and later). He graduated from the Department of Electrical Engineering in 1923 and became one of the first members of Nishi Takeshi's group at RIKEN. Nishi (1887–1944) was a specialist in high-voltage electrical engineering and a former member of Kujirai Tsunetarō’s group (see the next section), but he started to lead his own group in that year. Honda became a specialist in discharge phenomena and taught industrial physics at Tokyo Imperial University, eventually occupying the Chair of Industrial Physics of the Department of Physics. Thereafter, he was a principal facilitator of interactions between physicists and electrical engineers. The textbook Hoshiai and Honda wrote was an example of a bricolage of various physical and engineering theories and experiments. Starting with a classical kinetic theory of electrons, they used quantum theoretical notions – such as Fermi-Dirac statistics, light-quanta and the wave property of the electron – without providing any systematic exposition of quantum mechanics (Hoshiai and Honda Reference Hoshiai and Honda1936).
Soon, more textbooks appeared. In 1937, when a multi-volume textbook series on electronics was published, even first-rate atomic physicists were mobilized. Among the authors was Sugiura Yoshikatsu, who contributed a two-volume work entitled Denshi butsurigaku (Electron Physics). In these volumes, Sugiura presented quantum mechanical and statistical mechanical treatments of electrons, but, just like Hoshiai and Honda, he took a pragmatic approach. He limited the description to theories and experiments that he considered relevant to electronics, instead of systematically presenting all aspects of quantum mechanical studies of the electron (Sugiura Reference Sugiura1937).
At this point, the term denshi butsurigaku (electron physics) rather than denshiron was Sugiura's choice of vocabulary, probably to contrast with electronics (electron engineering). The Japanese term denshiron persisted much later, but, as in other languages, it was mainly applied to specific studies on electrons, such as theories of electrons in metals (kinzoku denshiron) or theories of the physical chemistry of electrons in molecules.Footnote 30 That is, therefore, a different breed of electron theory from the one discussed in this paper.
Thus, from 1905 to the early 1930s, denshiron (electron theory) was a subject about which Japanese physicists often talked or wrote. The subject included atomic physics, relativity theory, and light quantum theory. For a physicist like Kuwaki, electron theory was of interest because of the philosophical issues that it raised. However, for later authors, such as Mizuno, electron theory was a subject in which they could include various new developments in physics at that time, especially atomic physics, and present such new developments in a way relevant to electricity. Electron theory was never immediately useful for electrical engineering during this period, but physicists presented the physics of the electron as a foundation of all electrical phenomena, including electrical engineering, in their well-circulated textbooks and popular articles. These writings and activities of physicists, if not their research, made the utility of studies of electrons plausible enough for electrical engineers to invite physicists to talk about the electron at their meetings and hire a physicist to study vacuum tubes. This is what I mean by the context in which atomic physics was valued as a theory of the electron, and therefore valued as relevant to electrical engineering.
Electrical Engineering and Atomic Physics in RIKEN
It is not my claim that the context in which atomic physics was valued as a theory of the electron caused the development of atomic physics in Japan. There were various other socio-cultural factors that contributed. To discover the extent to which said context affected matters requires more extensive studies. In this section, I discuss just one example of how this context produced atomic physicists.
In 1916, Torikata, Yokoyama, and Kitamura received the prestigious Japan Academy Prize for their research on wireless telephony. There was one more recipient of the prize: Kujirai Tsunetarō (1884–1935). Kujirai was an extremely versatile electrical engineering researcher. Although he died young at the age of fifty, he worked on various topics and trained many able researchers, including Nishi Takeshi, Seto Shōji, Miyata Akira, Koga Issaku, and Nishina Yoshio. He graduated from the Department of Electrical Engineering at Tokyo Imperial University in 1907. His first position was in the Ministry of Communication, and he worked with Torikata at the Electrotechnical Laboratory. In the next year, he became an assistant professor at Tokyo Imperial University, where he worked on radiotelephony and developed a wireless transmitter probably independently of Torikata's group. While the TYK device used a self-adjusting spark gap, Kujirai employed a continuous discharge between a rotating carbon disk and an aluminum electrode. He acquired patents for his device (Kujirai Reference Kujirai1910, Reference Kujirai1911 and Reference Kujirai1912b), and he demonstrated his device to an audience of electrical engineers (Kujirai Reference Kujirai1912a). From 1912 to 1915, Kujirai studied electrical engineering in Europe and the United States.
In 1918, Kujirai was invited to join the Institute for Physical and Chemical Research (RIKEN) as one of the three kenkyūin (researchers)Footnote 31 in its physics department. RIKEN was established in 1917 as an institution dedicated solely to research in the fields of chemistry and physics.Footnote 32 It was modelled on European and American institutions, such as Physikalische-Technische Reichsanstalt, the National Bureau of Standards, and the National Physical Laboratory (Itakura and Yagi Reference Itakura, Yagi, Nakayama, Swain and Yagi1974; Saito Reference Saito1987). Despite its name, RIKEN's physics department was dominated by engineering researchers. Among the initial three researchers, two were engineering researchers. One was Kujirai and the other was Ōkōchi Masatoshi (1878–1952), an engineering professor at Tokyo Imperial University who specialized in gun manufacturing. Building No. 4, dedicated to electrical engineering, was the second building constructed in RIKEN (Rikagakukenkyūsho 1919). The building was equipped with power units that provided AC, DC, and high frequency electric sources (Ōkōchi Kinenkai 1954, 67).
In 1921, Ōkōchi became the third director of RIKEN. Under his leadership, RIKEN became an extremely productive research institute. One of his most important reforms was the way RIKEN garnered research funds by industrializing research outputs. Instead of relying on government subsidies or donations from the industry, Ōkōchi successfully generated revenues by industrializing and patenting RIKEN's inventions and even by establishing new companies. He then funded generously basic research (Saito Reference Saito1987).
Being a "chief scientist,” Kujirai led a group of researchers and had a certain budgetary autonomy. At RIKEN, Kujirai started new research projects, such as research related to electric furnaces, insulation, and secure communications. One of the most famous findings in his group was the discovery of “alumite” by Miyata Akira (1900–1984), who accidentally found a way to smooth the porous surface of the oxidization coating on aluminum. This procedure made aluminum products much more durable, bringing more income to RIKEN (Ko Kujirai Tsunetarō Kyōju Kinenjigyō Iinkai 1936)
Nishina Yoshio (1890–1951) was a postgraduate student (kenkyūsei) who joined Kujirai's group at RIKEN in 1918. He had just graduated from the department of electrical engineering of Tokyo Imperial University. Being a promising youth born before the Russo-Japanese War into a once wealthy but declining farming family, pursuing scientific interest with no regard to his country and his family was not an option. His natural career path would have been to secure a job at a good manufacturing company. Nishina, however, wanted to continue his studies, and he accepted Kujirai's offer of a position as a paid research student, declining the job at Shibaura Engineering Works.Footnote 33 At RIKEN, Nishina first conducted experiments with an electric furnace. Soon, however, he shifted his interest to atomic physics. In 1921, he left Japan for Europe and studied in Cambridge, Berlin, and Göttingen. In 1923, he moved to Niels Bohr's institute in Copenhagen, where he stayed until 1928, except for a six-month stay in Hamburg from 1927 to 1928. There, Nishina began as an X-ray spectroscopist with Dirk Coster as his mentor, but he eventually became a quantum physicist. The work in collaboration with Oskar Klein was based on a derivation of the Dirac theoretical formula for Compton scattering, which made their names appear in later textbooks. After visiting several places in the United States, Nishina came back to Japan in December 1928 as an internationally known atomic physicist (Ito Reference Ito2002 and Reference Ito2013; Kim Reference Kim2007).
At a party in Nishina's hometown to celebrate his return to Japan, his eldest brother, Teisaku, explained to the family and relatives that Nishina was studying electricity. Teisaku argued that, although the field of electricity in Japan was still in its infancy, it would greatly progress, and he called upon them to support Nishina (A. Nishina Reference Nishina1975). This was probably how non-specialists saw value in Nishina's research. Or, it might even be the way that Nishina explained the values of his research to his family. Teisaku's understanding of Nishina's expertise was not entirely incorrect because Nishina's work was very much about the electron, which might contribute to the studies of electricity. X-ray spectroscopy, quantum mechanics, and Dirac's theory were all heavily concerned with electrons (Ito Reference Ito2002 and Reference Ito2013). Either way, Nishina's conversion from electrical engineering to atomic physics was possible partially because it was initially not a conversion at all. If atomic physics was about the electron, and investigations of the electron would eventually contribute to electrical engineering, his study of atomic physics was legitimized in the eyes of his teachers, his colleagues, and his family.
Concluding Remarks
The aim of this paper is to describe some aspect of the social context in Japan's interwar period relevant to the emergence of atomic physics. This context enabled atomic physics to be considered as valuable because it concerned the electron. In this paper, I have illuminated this context by examining the general material cultures related to electrification and physicists' activities, including the publication of textbooks and popular writings. In these writings, physicists presented recent developments in atomic physics as "electron theory,” which was rendered relevant to electrical engineering. This suggests that there indeed was a context in which atomic physics was valued and legitimized as a theory of the electron because the latter was relevant to electrical engineering.
Similar to Hirosige's (Reference Hirosige, Nakayama, Swain and Yagi1974) account, this article does not provide the entire story. In particular, I stress that the existence of this context does not give a causal explanation of the development of atomic physics. For knowledge to circulate and develop, social support is usually necessary, but the form of support and the way it contributes to the development of knowledge depend on specific circumstances. This article does not examine how such support affected knowledge, except in the case of Nishina. Nor does it examine more specific ways in which atomic physics was valued. For example, we can surmise that Mizuno's textbook was very popular, but we still do not know what kind of readers read the book and in what ways. It is likely that there were certain educational demands, such as training of electrical engineers. These issues are beyond the scope of this paper.
In addition, electron theory is only part of the history of atomic physics in Japan. The development of atomic physics in Japan likely occurred as a consequence of multiple social factors. As mentioned in the introduction, one obvious background was the use of X-ray and radium in medicine and biology, which was particularly crucial for the development of nuclear physics in the 1930s. Another possible factor is the field of optics, which was important in the Japanese military, especially the navy. Japanese physicists, such as Nagaoka and Tsuruta Kenji, worked on optical devices and collaborated with companies like Nihon Kōgaku (Nikon) in order to produce better optical weapons for the Navy (Kōgaku Kōgyōshi Henshūkai 1955; Yamada Reference Yamada1969). An important field related to optics was spectroscopy, which, as I mentioned in the introduction, was a very active area of research in Japan and became essential for experiments in atomic physics. These, however, are topics for future papers.
Acknowledgments
The author thanks the participants of the workshop, “Interactions of Interwar Physics,” in particular its organizers, Shaul Katzir and Karl Hall, and the anonymous reviewers for their helpful comments and criticisms. The author also thanks Ms. Ishida of the SOKENDAI Library for her assistance. Preparation of this work was partially supported by JSPS Kakenhi Grant Numbers JP21500976, JP24501244, and JP17K01174.
