Properties and causes: An approach to the problem of hypothesis in the scientific methodology of Sir Isaac Newton

This article considers the differential absorption and integration of refugee physicists into various countries during the 1930s, and the social and intellectual factors responsible for this, focusing particularly on the social functions of the British and American university at that period, as well as continuing ideological struggles in the Soviet Union. More generally, the issue of the relative absorption of refugee physicists is used to examine the nature of the physics communities and other institutions of the host societies.     

The uncertainty principle – A simplified review of the four versions

The complexity of the historical confusions around different versions of the uncertainty principle, in addition to the increasing technicality of physics in general, has made its affairs predominantly accessible only to specialists. Consequently, the clarity that has dawned upon physicists over the decades regarding quantum uncertainty remains mostly imperceptible for general readers, students, philosophers and even non-expert scientists. In an attempt to weaken this barrier, the article presents a summary of this technical subject, focussing at the prime case of the position-momentum pair, as modestly and informatively as possible. This includes a crisp analysis of the historical as well as of the latest developments. In the process the article provides arguments to show that the usually sidelined version of uncertainty—the intrinsic ׳unsharpness׳ or ׳indeterminacy׳—forms the basis for all the other three versions, and subsequently presents its hard philosophical implications.     

A Companion to the History of Science

Snell's law of refraction did not affect the study of optics until twenty‐five years after its publication in 1637 and by then its universality threatened to break down already. Two optical phenomena—colour dispersion and strange refraction—were discovered that did not conform to the sine law. In the early 1670s, Isaac Newton and Christiaan Huygens respectively investigated these phenomena. They tried to describe the irregular behaviour of light rays mathematically and to reconcile it with ordinary refraction. This paper discusses their investigations and aims at throwing new light on the history of seventeenth‐century optics. Both initially approached the problem in a mathematical way in which they built on Descartes' analysis of refraction. This is surprising because it contradicts their earlier dismissal of Descartes' account and it does not fit our picture of them as mathematical physicists. By looking more closely at their early investigations it becomes clear that Newton and Huygens first had to develop the approach to optics of their later writings. After Descartes placed the issue of the physical nature of light rays on the scientific agenda in 1637, they recognized its purport in their struggles with colour dispersion and strange refraction. It was at this point that their physical optics evolved from the traditional geometrical optics with which they had started.     

To envision a new particle or change an existing law? Hypothesis formation and anomaly resolution for the curious case of the β decay spectrum

This paper addresses the question of how scientists determine which type of hypothesis is most suitable for tackling a particular problem by examining the historical case of the anomalous β spectrum in early nuclear physics (1927–1934), a puzzle that occasioned the most diverse hypotheses amongst physicists at the time. It is shown that such determinations are most often implicitly informed by scientists' individual perspectives on the structural relations between the various elements of the theory and the problem at hand. In addition to this main result, it is suggested that Wolfgang Pauli's neutrino idea may well have been an adaptation of Ernst Rutherford's original and older neutron idea, which would provide evidence that the adaptation of older ideas is a more common practice than is often thought.     

Mach׳s principle as action-at-a-distance in GR: The causality question

A part of the revival of interest in Mach׳s principle since the early 1960s has involved work by physicists aimed at calculating various sorts of frame-dragging effects by matter shells surrounding an interior region, and arguing that under certain conditions or in certain limits (ideally, ones that can be viewed as plausibly similar to conditions in our cosmos) the frame dragging becomes “complete” (e.g. Lynden-Bell, Katz, & Bičák, 1995) . Such results can bolster the argument for the satisfaction of Mach׳s principle by certain classes of models of GR. Interestingly, the frame-dragging “effect” of (say) a rotational movement of cosmic matter around a central point is argued by these physicists to be instantaneous—not an effect propagating at the speed of light. Not all physicists regard this as unproblematic. But rather than exploring whether there is something unphysical about such instantaneous “action at a distance”, or a violation of the precepts of Special Relativity, I am interested in exploring whether these physicists׳ calculations should be thought of as showing local inertia (resistance to acceleration) to be an effect, with distant matter distributions being the cause. I will try to apply some leading philosophical accounts of causation to the physical models of frame dragging, to see whether they imply that the frame dragging is superluminal causation. I will then offer reflections on the difficulties of applying causal talk in physical theories.     

Reception and discovery: the nature of Johann Wilhelm Ritter’s invisible rays

Ultraviolet radiation is generally considered to have been discovered by Johann Wilhelm Ritter in 1801. In this article, we study the reception of Ritter’s experiment during the first decade after the event—Ritter’s remaining lifetime. Drawing on the attributional model of discovery, we are interested in whether the German physicists and chemists granted Ritter’s observation the status of a discovery and, if so, of what. Two things are remarkable concerning the early reception, and both have to do more with neglect than with (positive) reception. Firstly, Ritter’s observation was sometimes accepted as a fact but, with the exception of C. J. B. Karsten’s theory of invisible light, it played almost no role in the lively debate about the nature of heat and light. We argue that it was the prevalent discourse based on the metaphysics of Stoffe that prevented a broader reception of Ritter’s invisible rays, not the fact that Ritter himself made his findings a part of his Naturphilosophie. Secondly, with the exception of C. E. Wünsch’s experiments on the visual spectrum, there was no experimental examination of the experiment. We argue that theorizing about ontological systems was more common than experimenting, because, given its social and institutional situation, this was the appropriate way of contributing to physics. Consequently, it was less clear in 1810 than in 1801 what, if anything, had been discovered by Ritter.     

From aether impulse to QED: Sommerfeld and the Bremsstrahlen theory

The radiation that is due to the braking of charged particles has been in the focus of theoretical physics since the discovery of X-rays by the end of the 19th century. The impact of cathode rays in the anti-cathode of an X-ray tube that resulted in the production of X-rays led to the view that X-rays are aether impulses spreading from the site of the impact. In 1909, Arnold Sommerfeld calculated from Maxwell׳s equations the angular distribution of electromagnetic radiation due to the braking of electrons. He thereby coined the notion of “Bremsstrahlen.” In 1923, Hendrik A. Kramers provided a quantum theoretical explanation of this process by means of Bohr׳s correspondence principle. With the advent of quantum mechanics the theory of bremsstrahlung became a target of opportunity for theorists like Yoshikatsu Sugiura, Robert Oppenheimer, and–again–Sommerfeld, who presented in 1931 a comprehensive treatise on this subject. Throughout the 1930s, Sommerfeld׳s disciples in Munich and elsewhere extended and improved the bremsstrahlen theory. Hans Bethe and Walter Heitler, in particular, in 1934 presented a theory that was later regarded as “the most important achievement of QED in the 1930s” (Freeman Dyson). From a historical perspective the bremsstrahlen problem may be regarded as a probe for the evolution of theories in response to revolutionary changes in the underlying principles.     

On a Lecture Trip to Spain: the Scientific Relations Between Germany and Spain During the Entente Boycott (1919–1926)

The aim of this paper is to analyse the scientific relations between Germany and Spain during the Entente Boycott (1919–1926) and the German academic policy that fostered it. The study of the international relations of German science during the 1920s has been carried out using as a basis the archives of scientific institutions. Personal initiatives by individual scientists to establish relations have therefore not been taken into account. The relations between the scientific communities of Germany and Spain during the 1920s indicate the importance of such personal relationships and from their transcendence at a political level. They also offer an example of how political strategies could dictate the politics of academic recognition. This paper is based on the analysis of sources found at the Foreign Office Archives in Berlin. It gives us a clear idea about the role of scientific relationships between the two countries in shaping their scientific policies.     

The co-discovery of conservation laws and particle families

This paper presents an epistemological analysis of the search for new conservation laws in particle physics that was especially prominent in the 1950s and 1960s. Discovering conservation laws has posed various challenges concerning the underdetermination of theory by evidence, to which physicists have found various responses. These responses include an appeal to a plenitude principle, a maxim for inductive inference, looking for a parsimonious system of generalizations, and unifying particle ontology and particle dynamics. The connection between conservation laws and ontological categories is a major theme in my analysis: While there are infinitely many conservation law theories that are empirically equivalent to the laws physicists adopted for the fundamental standard model of particle physics, I show that the standard family laws are the only ones that determine and are determined by the simplest division of particles into families.     

Feyerabend,truth, and relativisms: Footnotes to the Italian debate

There is a substantial literature on Feyerabend's relativism—including a few papers in this collection—but fewer specific studies of the ways that his writings and ideas have been taken up among the non-academic public. This is odd, given his obvious interest in the lives and concerns of persons who were not ‘intellectuals’—a term that, for him, had a pejorative ring to it. It is also odd, given the abundance of evidence of how Feyerabend's relativism played a role in a specific national and cultural context—namely, contemporary Italian debates about relativism. This paper offers a study of how Feyerabend's ideas have been deployed by Italian intellectuals and cultural commentators—including the current Pope—and critically assesses them.     

Quantum dissidents: Research on the foundations of quantum theory circa 1970

This paper makes a collective biographical profile of a sample of physicists who were protagonists in the research on the foundations of quantum physics circa 1970. We study the cases of Zeh, Bell, Clauser, Shimony, Wigner, Rosenfeld, d’Espagnat, Selleri, and DeWitt, analyzing their training and early career, achievements, qualms with quantum mechanics, motivations for such research, professional obstacles, attitude towards the Copenhagen interpretation, and success and failures. Except for Rosenfeld, they were all dissidents, fighting against the dominant attitude among physicists at the time according to which foundational issues had already been solved by the founding fathers of the discipline. Theirs is a story of success as the foundations of quantum mechanics finally entered the physics mainstream despite the fact that their expectations of breaking down quantum mechanics were not fulfilled.     

Setting up a Discipline: Conflicting Agendas of the Cambridge History of Science Committee, 1936–1950

Traditionally the domain of scientists, the history of science became an independent field of inquiry only in the twentieth century and mostly after the Second World War. This process of emancipation was accompanied by a historiographical departure from previous, ‘scientistic’ practices, a transformation often attributed to influences from sociology, philosophy and history. Similarly, the liberal humanists who controlled the Cambridge History of Science Committee after 1945 emphasized that their contribution lay in the special expertise they, as trained historians, brought to the venture. However, the scientists who had founded the Committee in the 1930s had already advocated a sophisticated contextual approach: innovation in the history of science thus clearly came also from within the ranks of scientists who practised in the field. Moreover, unlike their scientist predecessors on the Cambridge Committee, the liberal humanists supported a positivistic protocol that has since been criticized for its failure to properly contextualize early modern science. Lastly, while celebrating the rise of modern science as an international achievement, the liberal humanists also emphasized the peculiar Englishness of the phenomenon. In this respect, too, their outlook had much in common with the practices from which they attempted to distance their project.     

From ‘Beastly Philosophy’ to Medical Genetics: Eugenics in Russia and the Soviet Union

This essay offers an overview of the three distinct periods in the development of Russian eugenics: Imperial (1900–1917), Bolshevik (1917–1929), and Stalinist (1930–1939). Began during the Imperial era as a particular discourse on the issues of human heredity, diversity, and evolution, in the early years of the Bolshevik rule eugenics was quickly institutionalized as a scientific discipline—complete with societies, research establishments, and periodicals—that aspired an extensive grassroots following, generated lively public debates, and exerted considerable influence on a range of medical, public health, and social policies. In the late 1920s, in the wake of Joseph Stalin's ‘Great Break’, eugenics came under intense critique as a ‘bourgeois’ science and its proponents quickly reconstituted their enterprise as ‘medical genetics’. Yet, after a brief period of rapid growth during the early 1930s, medical genetics was dismantled as a ‘fascist science’ towards the end of the decade. Based on published and original research, this essay examines the factors that account for such an unusual—as compared to the development of eugenics in other locales during the same period—historical trajectory of Russian eugenics.     

Mathematical understanding and the physical sciences

The author claims to have developed interactional expertise in gravitational wave physics without engaging with the mathematical or quantitative aspects of the subject. Is this possible? In other words, is it possible to understand the physical world at a high enough level to argue and make judgments about it without the corresponding mathematics? This question is empirically approached in three ways: (i) anecdotes about non-mathematical physicists are presented; (ii) the author undertakes a reflective reading of a passage of physics, first without going through the maths and then after engaging with it and discusses the difference between the experiences; (iii) the aforementioned exercise gives rise to a table of Levels of Understanding of mathematics, and physicists are asked about the level mathematical understanding they applied when they last read a paper. Each phase of empirical research suggests that mathematics is not as central to gaining an understanding of physics as it is often said to be. This does not mean that mathematics is not central to physics, merely that it is not essential for every physicist to be an accomplished mathematician, and that a division of labour model is adequate. This, in turn, suggests that a stream of undergraduate physics education with fewer mathematical hurdles should be developed, making it easier to train wider groups of people in physical science comprehension.     

Radiation physics

Summary A review is presented of the recent literature in the areas of physics which deal with radiation effects on man and animals. Some consideration is given to natural and artificial radiation sources such as cosmic rays, radon and high energy accelerators. The interaction of radiation with matter is treated if it is related to an energy deposition pattern relevant to biological effects. Dosimetry is also treated, with special emphasis on papers dealing with spatial dose distribution on a microscopic level, and radiobiological models relating the energy deposition pattern to biological effects are cited. New techniques in the medical application of radiation in diagnostics and therapy are briefly mentioned.     

Radiation physics

A review is presented of the recent literature in the areas of physics which deal with radiation effects on man and animals. Some consideration is given to natural and artificial radiation sources such as cosmic rays, radon and high energy accelerators. The interaction of radiation with matter is treated if it is related to an energy deposition pattern relevant to biological effects. Dosimetry is also treated, with special emphasis on papers dealing with spatial dose distribution on a microscopic level, and radiobiological models relating the energy deposition pattern to biological effects are cited. New techniques in the medical application of radiation in diagnostics and therapy are briefly mentioned.     

Genesis of Karl Popper's EPR-like experiment and its resonance amongst the physics community in the 1980s

I present the reconstruction of the involvement of Karl Popper in the community of physicists concerned with foundations of quantum mechanics, in the 1980s. At that time Popper gave active contribution to the research in physics, of which the most significant is a new version of the EPR thought experiment, alleged to test different interpretations of quantum mechanics. The genesis of such an experiment is reconstructed in detail, and an unpublished letter by Popper is reproduced in the present paper to show that he formulated his thought experiment already two years before its first publication in 1982. The debate stimulated by the proposed experiment as well as Popper's role in the physics community throughout 1980s is here analysed in detail by means of personal correspondence and publications.     

Giulio Racah and theoretical physics in Jerusalem

The present article considers Giulio Racah’s contributions to general physical theory and his establishment of theoretical physics as a discipline in Israel. Racah developed mathematical methods that are based on tensor operators and continuous groups. These methods revolutionized spectroscopy. Currently, these are essential research tools in atomic, nuclear and elementary particle physics. He himself applied them to modernizing theoretical atomic spectroscopy. Racah laid the foundations of theoretical physics in Israel. He educated several generations of Israeli physicists, and put Israel on the world map of physics.     

History of the Lenz–Ising Model 1950–1965: from irrelevance to relevance

This is the second in a series of three papers that charts the history of the Lenz–Ising model (commonly called just the Ising model in the physics literature) in considerable detail, from its invention in the early 1920s to its recognition as an important tool in the study of phase transitions by the late 1960s. By focusing on the development in physicists’ perception of the model’s ability to yield physical insight—in contrast to the more technical perspective in previous historical accounts, for example, Brush (Rev Modern Phys 39: 883–893, 1967) and Hoddeson et al. (Out of the Crystal Maze. Chapters from the History of Solid-State Physics. Oxford University Press, New York, pp. 489–616, 1992)—the series aims to cover and explain in depth why this model went from relative obscurity to a prominent position in modern physics, and to examine the consequences of this change. In the present paper, which is self-contained, I deal with the development from the early 1950s to the 1960s and document that this period witnessed a major change in the perception of the model: In the 1950s it was not in the cards that the model was to become a pivotal tool of theoretical physics in the following decade. In fact, I show, based upon recollections and research papers, that many of the physicists in the 1950s interested in understanding phase transitions saw the model as irrelevant for this endeavor because it oversimplifies the nature of the microscopic constituents of the physical systems exhibiting phase transitions. However, one group, Cyril Domb’s in London, held a more positive view during this decade. To bring out the basis for their view, I analyze in detail their motivation and work. In the last part of the paper I document that the model was seen as much more physically relevant in the early 1960s and examine the development that led to this change in perception. I argue that the main factor behind the change was the realization of the surprising and striking agreement between aspects of the model, notably its critical behavior, and empirical features of the physical phenomena.     

James Franck,the ionization potential of helium,and the experimental discovery of metastable states

In 1920, James Franck together with Fritz Reiche and Paul Knipping found strong experimental evidence that the lowest-lying triplet state in helium is metastable—an atom in this state cannot make a spontaneous transition to the ground state. Even though their evidence was entirely experimental, they tied their results almost inextricably to Alfred Landé’s 1919 model of the helium atom, and in the process, misunderstood the new theoretical selection rules of Adalbert Rubinowicz and Niels Bohr. In an additional complication, experiments of the English physicists Frank Horton and Ann Catherine Davies contradicted Franck’s. Although Franck’s result has held up, the reasons for the discrepancies remain unclear.