The European Physical Journal H最新文献

Einstein's expression ‘Drama of Ideas’ to describe the history of fundamental physics is especially suitable for the problem of quantum gravity (QG). The problem was identified by Einstein in 1916 based on an empirico-cosmological argument that was cosmologically flawed and empirically immeasurable. In 1929, the problem was strikingly underestimated by prominent figures in quantum theory, W. Heisenberg and W. Pauli. In 1929, Bohr, basing on the puzzling results of recent nuclear experiments and theoretical quantum limitations, hypothesized that the law of conservation of energy does not hold in nuclear physics. The young Russian physicist Landau enthusiastically supported Bohr's ‘beautiful idea’ and in 1931 proposed its theoretical justification, which, however, was rejected by Bohr. In late 1932, Landau realized that Bohr's hypothesis was incompatible with Einstein's theory of gravity. This meeting of two fundamental theories prompted Matvei Bronstein to investigate the quantization of gravity in-depth. In 1935, he proposed the first physical theory of QG for the weak gravity and revealed how deep the QG problem was for strong gravity. He showed that the gravitational field at a point in space–time is in principle unobservable and concluded that a complete theory of QG would require the ‘rejection of a Riemannian geometry… and perhaps also the rejection of our ordinary concepts of space and time, replacing them by some much deeper and non-evident concepts’. Until now, despite thousands of publications on QG, the problem remains a great challenge in theoretical physics.

In spring 1949 about 70 physicists from eight countries met in Florence to discuss recent trends in statistical mechanics. This scientific gathering, co-organized by the Commission on Thermodynamics and Statistical Mechanics of the International Union of Pure and Applied Physics (IUPAP) and the Italian Physical Society (SIF), initiated a tradition of IUPAP-sponsored international conferences on statistical mechanics that lasts to this day. In 1977, when this conference series took the name of StatPhys, the foundational role of the Florence conference was recognized by retrospectively naming it StatPhys1. This paper examines the dual scientific and social significance of the conference, situating it in the broader contexts of the post-World War II reconstruction in Italian physics and of the revitalization of the international science organization. Through an analysis of IUPAP archives and Italian records, we illustrate how the event’s success hinged on the aligned objectives of its organizers. Internationally, it was instrumental in defining the scientific and organizational foundations for the activities of IUPAP commissions during a critical phase of IUPAP’s history, when the Union was resurging on the international scene after the inactivity of the interwar period. Nationally, the conference served as a cornerstone in SIF’s strategy to re-establish Italian physics’ international stature and to aid the domestic revitalization of physics through the internationalization of its activities, notably of its flagship journal, Il Nuovo Cimento. This analysis not only sheds light on the conference’s impact but also informs recent discussions in the history of science about the multiple roles of international scientific conferences.

The onset and the development of the concept of exchange force in quantum physics are historically reconstructed, starting from Heisenberg’s seminal contributions in 1926 and going through the great developments in nuclear physics, which allowed the emergence of the idea of force mediating virtual quanta. Although most of such work was performed in Europe, the last and decisive effort in this long path was carried out by Japanese scientists in the 1930s. This is the main focus of the present work, which retraces the achievements of Yukawa and Tomonaga, whose results and mutual interactions are carefully analyzed and related to those of European physicists.

Pascual Jordan was the first to propose the law of interference of probability amplitudes as a principle of quantum mechanics. We analyze the role of probabilistic ideas played in this proposal from a historical perspective. In particular, we point out the relation between the usual theory of probability that Jordan called elementary and quantum mechanics. Jordan was the first to stress the analogy between the law of total probability and the law of interference. In this regard, we speculate about the intellectual path Jordan might have followed in order to arrive at the interference law. We do not oppose the usual probability to quantum probability. Instead, we are convinced, as Jordan was, that the rules of quantum mechanics are the rules of a probability theory that has ceased to be elementary.

We reconstruct the intriguing case of the formation of the Naples group of Statistical Mechanics, which took more than two decades, from the first steps at the end of 1960 aimed at acquiring skills and knowledge abroad, until the formal establishment of the group at the beginning of the 1990 s. A number of important results were obtained seamlessly during this period by Antonio Coniglio and his large number of collaborators, but although favorable opportunities for the formation of the group emerged, starting from the beginning of the 1980 s, several factors (including a certain disinterest in supporting research in Italy) effectively delayed the formation of a group by about a decade. We here provide a fairly comprehensive picture of the relevance of the group of Neapolitan statistical physicists even before its formation, also reviewing the main contributions achieved by these people both during the process of formation of the group and in the first decade of its life.

Robert A. Millikan (1868–1953) was the second American to win the Nobel Prize in physics. At the peak of his influence, no scientist save Einstein was more admired by the American public. Millikan, the head of the California Institute of Technology (Caltech) during its first 24 years, oversaw its rapid growth into one of the leading scientific institutions of the world. However, in response to demands for social justice following the murder of George Floyd, Caltech launched an investigation into Millikan. Caltech reached a decision to strip Millikan of honors (such as the library named after him), following accusations from various sources that he was a sexist, racist, xenophobic, antisemitic, pro-eugenic Nazi sympathizer. In short, Caltech threw the book at him. This article analyzes two accusations against Millikan. The first of these accusations was published in Nature: that he collaborated to deprive Japanese Americans of their rights during their forced relocation to internment camps during the Second World War. An examination of original historical sources will show that this accusation is false. On the contrary, Millikan actively campaigned during the war to promote the rights of Japanese Americans. This article traces the stages of misrepresentation that led to current false beliefs about Millikan. In view of Millikan’s extraordinary position in American science, this misrepresentation is a cautionary tale. The article also treats Caltech’s central accusation against Millikan: he lent his name to “a morally reprehensible eugenics movement” that had been scientifically discredited in his time. The article considers the statements purporting to show that eugenics movement had been denounced by the scientific community by 1938. In a reversal of Caltech’s claims, all three of Caltech’s scientific witnesses against eugenics—including two Nobel laureates—were actually pro-eugenic to varying degrees. This article concludes that Millikan’s beliefs fell within acceptable scientific norms of his day.

Perturbative expansions have played a peculiarly central role in quantum field theory, not only in extracting empirical predictions but also in investigations of the theory’s mathematical and conceptual foundations. This paper brings the special status of QFT perturbative expansions into focus by tracing the history of mathematical physics work on perturbative QFT and situating a contemporary approach, perturbative algebraic QFT, within this historical context. Highlighting the role that perturbative expansions have played in foundational investigations helps to clarify the relationships between the formulations of QFT developed in mathematical physics and high-energy phenomenology.

The Italian theorist Gian-Carlo Wick is well known for his work in mathematical physics. Nevertheless, working with Fermi’s group in Rome in the 1930s, he took on several behind-the-scenes roles that resulted in important papers in neutron physics. He clarified Fermi’s methodology for calculating neutron slowing down probabilities; using transport theory, he provided a comprehensive general method for calculating the neutron scattering albedo; and with an insight into the way, neutron scattering could yield information about lattice dynamics, he formulated the first theory of inelastic thermal neutrons scattering in crystalline materials. This work and his contributions are not well known today. We discuss its physical essence, its relevance to neutron physics, and its subsequent impact in later work.