Physics in Perspective最新文献

We reconstruct Enrico Fermi’s remarkable discovery of neutron-induced radioactivity in March 1934 with a focus on the experimental apparatus he used, such as the original neutron sources preserved in Italy and abroad. Special attention is paid to the role of the Radium Office of the Institute of Public Health in Rome in providing to Fermi the “radium emanation” (Radon-222) used to make his radon-beryllium neutron sources. This particular angle of investigation allows us to make a full reconstruction of what Fermi actually realized in his laboratory, to gain a better insight into his methodological choices, and, ultimately, to understand how special circumstances conspired to make the discovery of neutron-induced radioactivity possible.

The paper is focused on the two most outstanding figures among the Jesuit missionaries in seventeenth-century China: Johann Adam Schall von Bell and Ferdinand Verbiest. Schall aimed to introduce the telescope into Chinese astronomy, which was traditionally based on naked-eye observation and calculation. With the advent of the Qing dynasty, he became head of the Mathematical Board and director of the Imperial Observatory. Verbiest was called upon in 1660 to assist Schall in his project of reforming the Chinese traditional calendar. The political situation changed in 1661, with the Empire ruled by a regency hostile to the Jesuits, as were most of the mandarins at the observatory. This was the difficult context of the famous dispute between Yang Guangxian, Wu Mingxuan, and the two Jesuit mathematicians to compare the merits of Western and Chinese astronomy, which lasted from 1664 to 1669. What happened was more than a scientific contest and a court conspiracy: it was a cultural confrontation between the Jesuits and the traditionalist side of the ruling elite, which regarded the Europeans and their increasing influence as a threat for the Empire.

Western missionaries played an important role as go-betweens, promoting communication and interaction between Europe and China in science, culture, and religion. In 1644, the Qing government appointed the Germany Jesuit missionary Johann Adam Schall von Bell head of the Bureau of Astronomy, placing him in charge of reforming the Chinese calendar. In the traditional calendar, in addition to dates based on astronomical calculation, there were annotations attached to each day, which included auspicious and inauspicious days with advice on what to do in daily life according to Chinese astrology. Schall reformed the time arrangements with Western astronomical methods. However, he hoped to go further and proposed to change the annotations on the basis of Western natural astrology. Why did Schall choose to import Western astrology into Chinese astronomy, rather than simply sticking to astronomy? I argue that his views were influenced by both the attitudes of the Roman Catholic Church and the Aristotelianism scholarly tradition. The underlying tensions between Europe and China did not involve conflicts between science and pseudoscience, but between different religious beliefs, as well as different natural philosophies and cosmologies. The encounter of two radically different cultural traditions reflected the complicated relationship between science and belief from a global point of view.

The concept of “fact” has a history. Over the past centuries, physicists have appropriated it in various ways. In this article, we compare Ernst Mach and Albert Einstein’s interpretations of the concept. Mach, like most nineteenth-century German physicists, contrasted fact and theory. He understood facts as real and complex combinations of natural events. Theories, in turn, only served to order and communicate facts efficiently. Einstein’s concept of fact was incompatible with Mach’s, since Einstein believed facts could be theoretical too, just as he ascribed mathematical theorizing a leading role in representing reality. For example, he used the concept of fact to refer to a generally valid result of experience. The differences we disclose between Mach and Einstein were symbolic for broader tensions in the German physics discipline. Furthermore, they underline the historically fluid character of the category of the fact, both within physics and beyond.

As the History of Science Society, which is based in America, holds its annual meeting in Utrecht, one of the key academic centers on the European continent, one may surmise that the field has returned home. Yet, this hardly reflects how today’s world of scholarship is constituted: in the historiography of science, “provincializing Europe” has become an important theme, while the field itself, as is the case across the world of academia, is centered around a predominantly American literature. At the same time, ever since historians of science emancipated themselves from the sciences a long time ago, they often have appeared, in the public eye, to question rather than to seek to bolster the authority of the sciences. How has this situation come about, and what does it tell us about the world we live in today? What insight is sought and what public benefit is gained by the historical study of science? As we try to answer these questions, we will follow a number of key mid-twentieth-century historians—Eduard Dijksterhuis, Thomas Kuhn, and Martin Klein—in their Atlantic crossings. Their answers to debates on the constitution of the early modern scientific revolution or the novelty of the work of Max Planck will illustrate how notions of “center” and “periphery” have shifted—and what that may tell us about being “in Europe” today.

The American physicist John Wheeler once told his colleague Richard Feynman that, in case of war, “it’s better to forget physics and tell the admirals and generals how to do tactical and strategic this-and-that.” This article explores the history of this-and-that distinctions between tactical and strategic nuclear weapons in the early Cold War. The idea of tactical nuclear weapons was intertwined with the work of a small group of defense intellectuals on limited nuclear war who explicitly framed the idea of tactical nuclear weapons as “arbitrary” and “illogical,” but nonetheless crucial to the continued survival of the Free World, as they understood it. I follow several strains of this complex history to show how a subset of these theorists viewed the new category of tactical nuclear weapons as an antidote to declining civilization and the embodiment of an anti-rationalist and anti-empiricist way of making knowledge about the world.

Einstein’s life-long effort to develop a theory that unifies gravitation and electromagnetism was not a purely theoretical enterprise. The technical environment of a gyrocompass factory triggered his search for a novel connection between the rotation of an electrically uncharged body and its magnetic field. The dimensional equality of the electric unit charge and the mass of a body multiplied by the square root of the gravitational constant hinted at a nonsensical electric charge, to which he gave the name “ghost charge.” He felt that he found a fundamental unity of gravitating mass and electricity, a hitherto undiscovered law of nature. Two physicists offered to assist him in finding evidence of this peculiar electric charge. Peter Pringsheim performed experiments with deionized gases and Teodor Schlomka made measurements of the earth’s magnetic field from balloons and airplanes; Schlomka also executed a thorough literature search and placed Einstein’s efforts in their historical context.