The European Physical Journal H最新文献

Hilbert-space techniques are widely used not only for quantum theory, but also for classical physics. Two important examples are the Koopman-von Neumann (KvN) formulation and the method of “classical” wave functions. As this paper explains, these two approaches are conceptually distinct. In particular, the method of classical wave functions was not due to Bernard Koopman and John von Neumann, but was developed independently by a number of later researchers, perhaps first by Mario Schönberg, with key contributions from Angelo Loinger, Giacomo Della Riccia, Norbert Wiener, and E. C. George Sudarshan. The primary goals of this paper are to explain these two approaches, describe the relevant history in detail, and give credit where credit is due.

Seismology, which had previously relied on descriptive and observational methods, began incorporating appropriate instrumentation and effective techniques for the parametric and theoretical analysis of seismic data starting in the mid-nineteenth century. Alessandro Serpieri, rector of the Raffaello College in Urbino from 1857 to 1884, was a pioneering figure who first proposed the creation of a seismic network in Italy. A significant contribution also came from Luigi Guidi (1824–1883), director from 1861 to 1883 of the Valerio Observatory in Pesaro. Today, comprehensive coverage of study areas is essential for the high-resolution analysis of low-magnitude seismic events. To this end, a temporary seismic network was established in the Montefeltro region in December 2018 as part of a collaborative project between the University of Urbino and the National Institute of Geophysics and Volcanology. The aim was to acquire new seismic data to supplement those recorded by the National Seismic Network. The Montefeltro area, with Urbino as its provincial capital, has recently experienced seismic activity with magnitudes below 4. Data analysis indicates that the region is characterized by a seismically active basin with microseismicity, while the surrounding areas show more concentrated seismic activity in three zones: Rimini, Forlì, and along the Apennine belt. In this contribution, we review the evolution of seismological studies in the broad Montefeltro region since the seminal work of Serpieri up to present times.

I study Heisenberg's 1939 chain reaction equation as an eigenvalue problem for nonspherical shapes and apply it to calculate the criticality condition of the cylindrical 1945 Haigerloch reactor experiment B₈. I also discuss Heisenberg's B₈ criticality analysis where he relied on his 1939 spherical result that the neutron current ratio is infinite at criticality. I show that that result holds for a sphere but not for a cylinder. His wrong expectation for a cylinder has recently been assumed in simulations of B₈. Heisenberg and Wirtz applied an inconsistent mix of spherical and axial extrapolations to B₈ that led Heisenberg to predict that they needed a radial increase of 20 cm to reach criticality. The B₈ reactor was designed with the height twice the radius, H = 2R, so that a sphere of radius R fits perfectly inside the cylinder, apparently with the application of his 1939 spherical calculation in mind. I solve Heisenberg's reactor equation for axial symmetry and the full tamper boundary condition. Diffusion theory with the tamper then predicts that the reactor should have been slightly subcritical, while Heisenberg's albedo boundary condition predicts slight supercriticality. Diffusion theory therefore predicts that the reactor was very near to criticality. I also consider how the reactor's designers may have arrived at a nearly correct size of B₈ without doing a correct cylindrical calculation.

The paper examines the historical development and context of several seismographs preserved in the Physics Laboratory and Museum of Science and Technology at the University of Urbino Carlo Bo. In the second half of the nineteenth century, these instruments were used by Alessandro Serpieri (1823–1885), a Scolopian priest and a pioneer of Italian seismology. Following a brief biographical overview of the scientist, the study examines three principal instruments currently on display in the museum: the “protoseismograph” by Michele Stefano De Rossi (1878) and two seismographs designed by the Urbino-based instrument-maker Achille Scateni (c. 1882). In addition to these surviving instruments, the study also discusses a seismograph invented by Serpieri in 1873, known only through contemporary descriptions and illustrations. This study re-examines their history and mechanical functioning using archival documents, publications from the period, and direct analysis of the instruments, focusing on Luigi Palmieri’s influence on Serpieri’s seismograph design. It highlights the scientific heritage of Urbino’s Physics Laboratory and the pivotal collaboration between Serpieri and Scateni, locating their advancements in Italian instrumental seismology within the context of the birth of quantitative seismometry which complemented continuing observational methods in the late nineteenth century. In particular, it suggests how the interplay between local instrumental innovation and national scientific networks fostered the development of modern seismometry in Italy.

Building on Schrödinger's original formulation of quantum mechanics from 1926, which initially involved a fourth-order differential equation, this article explores the mechanical analogy between this first Schrödinger equation without potential V and the dynamic behavior of vibrating elastic structures in the specific case of a particle in a potential well. Revisiting this fourth-order approach, we find a mathematical equivalence with the modern second-order Schrödinger equation which is strictly equivalent to the initial fourth-order Schrödinger equation in this specific case, while also revealing the possibility of solutions positive and negative masses. These results resonate with recent experimental observations on Bose–Einstein condensates and spin–orbit coupled exciton–polaritons. Following this research, it seems that negative mass effects should appear in the particular case of particles in a potential well situation close to this specific case like a Bose–Einstein condensate at a temperature close to 0 or another quantum entity in a cavity well.

The Manila Observatory, established in 1865, was a leading centre for geophysical research in the Far East for 80 years (1865–1945). It conducted pioneering studies in meteorology, geomagnetism, seismology, volcanology, and astronomy. Instrumental seismology began at the Observatory shortly after its founding, and its early development exhibited distinctive characteristics: It developed more rapidly than in Spain (the dominating power at that time) and it became a unique example of the Italian seismological tradition, particularly endogenous meteorology, taking root in Asia. Early Italian instruments such as seismographs, tromometers, and seismic telephones were installed and used extensively in Manila. By 1890, the Observatory became the central station of the Philippine seismological network. However, seismological research in the Philippines was not confined to the Observatory; other significant developments, especially in engineering seismology, also emerged during this period. This study offers an introductory analysis and evaluation of the early stages of instrumental seismology in the Philippines, highlighting its roots in the Italian seismological tradition—particularly the theories of endogenous meteorology—and its related scientific research.

When a physicist evokes the past, historians typically start rubbing their hands, waiting for their chance to correct the naive scientist who seems to intrude into their job. In this attitude too, however, there is a form of naiveté that can prevent us from appreciating and properly weighing many aspects of history. The manifold uses of the past by the physicists themselves, in particular, remain a neglected topic. This paper intends to show how an eminent figure such as John A. Wheeler (1911–2008), also thanks to his long life and career, created a highly peculiar—and, communication-wise, very effective—mixture of personal experience and reminiscences, historical pathos and anecdotes, guiding ideas and metaphors. The relevance of such amalgam is not limited to the employment of rhetoric in science, since it shaped Wheeler’s influential research programs and suggestions throughout decades, besides offering a powerfully evocative and captivating communicative model for the speculative frontiers of physics. While all this is meant as a study in the way Wheeler made use of the past within his activities as a physicist, it can also provide us with a critical lesson about today’s construction of pseudo-historical narratives that try to legitimize bold proposals in lack of empirical results.

This oral history interview provides Yakir Aharonov’s perspective on the theoretical discovery of the Aharonov-Bohm effect in 1959, during his PhD studies in Bristol with David Bohm, the reception of the effect, the efforts to test it empirically (up to Tonomura’s experiment), and some of the debates regarding the existence of the effect and its interpretation. The interview also discusses related later developments until the 1980s, including modular momentum and Berry’s phase. It includes recollections from meetings with Werner Heisenberg, Richard Feynman, and Chen-Ning Yang, also mentioning John Bell, Robert Chambers, Werner Ehrenberg, Sir Charles Frank, Wendell Furry, Gunnar Källén, Maurice Pryce, Nathan Rosen, John Wheeler, and Eugene Wigner.

In the previous paper, we have outlined the systematic interconnections that, between the 1950s and 1960s, Iron Curtain notwithstanding, prepared a unitary framework for the exploration of the “violent universe”, thanks to the emergence of new astronomies (radio, gamma, X-ray) and the rise of relativistic astrophysics. In this paper, we will zoom-in on a Soviet event, the nature of which is not entirely clear, that took place in Tartu in the summer of 1962. Calling attention to it will not only allow us to fill a historiographical gap (since the premonitions of relativistic and neutrino astrophysics that were discussed have eluded the historians’ attention), but also to highlight important elements of its broader context and focus on some significant personalities who were present there. In this way, we will further show how the conceptual links that we have previously traced were indeed embedded in the technological scenario of the Cold War, shaped by the arms race and the space race. Once these aspects are clarified, we will expand on three versatile personalities who, in different ways, embodied the flowing together of new physical, astronomical, and cosmological developments: I.S. Shklovsky, B.M. Pontecorvo and, perhaps more than anyone else, one of the former leaders of the Soviet H-bomb project, Ya.B. Zel’dovich. Starting from the period of the Tartu event, Zel’dovich put his military work to the side (but exapting new technological possibilities from that) and led one of the world’s most important groups in the newly born relativistic astrophysics, with all its implications and interconnections with fundamental physics. By sketching the outcomes of the research of these scientists around the year of the Tartu event and then throughout the 1960s, we will also be able to outline the transition from the early “shared culture” (1950s-beginning of the 1960s) that we have been emphasizing to the unified perspectives that emerged in the following decades, up to multimessenger astronomy.

Between the 1950s and early 1960s, the advent of radio, gamma-ray, and X-ray astronomy established deep links with the physical sciences, creating a new symbiosis between astronomy, physics, and cosmology. This relationship evolved in parallel with a revolutionized view of the universe, driven by novel cosmic messengers and the rise of relativistic astrophysics. We intend to show how, during this transitional period—shaped by the advent of the space age and embedded in the technological context of the Cold War—one can trace the harbingers of developments that would unfold from the 1970s and 1980s onwards, once astronomy had expanded to encompass the entire electromagnetic spectrum incorporating non-photonic messengers into the roster of possible cosmic signals to be used to study the Universe. In the early 1980s, the rise of particle astrophysics—a multidisciplinary field encompassing elementary particle physics, cosmology, and astrophysics—laid the groundwork for a cross-cultural alliance aimed at forging a broader foundation for a unified vision of the cosmos. This paper does not aim to retroactively trace the individual research paths of subcommunities of contemporary particle astrophysics. Rather, it seeks to highlight from a broad perspective, the advances that in the 1950s and 1960s had already paved the way for a radically new view of the cosmos, advances that were marked by the establishment of connections between different cosmic messengers and by synergic interactions and cross-fertilizations between different disciplinary cultures and communities, often separated by the Iron Curtain. In particular, we will emphasize how the key catalyst in linking previously separate scientific environments was the discovery of the Universe’s very high-energy phenomena: the violent Universe.