The European Physical Journal H最新文献

In the second half of the 19th century, a special practice of research and training in physics took shape in Pisa, characterized by a particular attention to theoretical studies and to combining experimental activity with a profound mastery of mathematical tools. This peculiar approach, started by Carlo Matteucci and Ottaviano Mossotti, continued and spread by Riccardo Felici, Enrico Betti, Adolfo Bartoli and Vito Volterra, was quite an exception in the framework generally marked by strict experimentalism and positivist empiricism of the Italian physics cabinets of the time. The present paper highlights a special path connecting this tradition of the Pisan school to the scientific environment that was formed in the early years of the 20th century at the Royal Physical Institute in Via Panisperna in Rome, through the interaction of Orso Mario Corbino with Volterra on one side, and the imprinting left on Corbino by Adolfo Bartoli and his student and collaborator Enrico Stracciati.

Interest in Brownian motion was shared by different communities: this phenomenon was first observed by the botanist Robert Brown in 1827, then theorised by physicists in the 1900s, and eventually modelled by mathematicians from the 1920s, while still evolving as a physical theory. Consequently, Brownian motion now refers to the natural phenomenon but also to the theories accounting for it. There is no published work telling its entire history from its discovery until today, but rather partial histories either from 1827 to Perrin’s experiments in the late 1900s, from a physicist’s point of view; or from the 1920s from a mathematician’s point of view. In this article, we tackle the period straddling the two ‘half-histories’ just mentioned, in order to highlight continuity, to investigate the domain-shift from physics to mathematics, and to survey the enhancements of later physical theories. We study the works of Einstein, Smoluchowski, Langevin, Wiener, Ornstein and Uhlenbeck from 1905 to 1934 as well as experimental results, using the concept of Brownian velocity as a leading thread. We show how Brownian motion became a research topic for the mathematician Wiener in the 1920s, why his model was an idealization of physical experiments, what Ornstein and Uhlenbeck added to Einstein’s results, and how Wiener, Ornstein and Uhlenbeck developed in parallel contradictory theories concerning Brownian velocity.

The quantum theory of dispersion was an important conceptual advancement which led out of the crisis of the old quantum theory in the early 1920s and aided in the formulation of matrix mechanics in 1925. The theory of Charles Galton Darwin, often cited only for its reliance on the statistical conservation of energy, was a wave-based attempt to explain dispersion phenomena at a time between the theories of Ladenburg and Kramers. It contributed to future successes in quantum theory, such as the virtual oscillator, while revealing through its own shortcomings the limitations of the wave theory of light in the interaction of light and matter. After its publication, Darwin’s theory was widely discussed amongst his colleagues as the competing interpretation to Compton’s in X-ray scattering experiments. It also had a pronounced influence on John C. Slater, whose ideas formed the basis of the BKS theory.

The idea of gravitational collapse can be traced back to the first solution of Einstein’s equations, but in these early stages, compelling evidence to support this idea was lacking. Furthermore, there were many theoretical gaps underlying the conviction that a star could not contract beyond its critical radius. The philosophical views of the early 20th century, especially those of Sir Arthur S. Eddington, imposed equilibrium as an almost unquestionable condition on theoretical models describing stars. This paper is a historical and epistemological account of the theoretical defiance of this equilibrium hypothesis, with a novel reassessment of J.R. Oppenheimer’s work on astrophysics.

This interview is focused on university studies and early career in relativity physics including thesis work under Leopold Infeld dealing with gravitational waves. Trautman’s recollections include the collaboration with Ivor Robinson and relationships with relevant personalities like Felix Pirani, Jerzy Plebanski, Roger Penrose and Peter Bergmann.

Considered one of the founding fathers of integral geometry, Luis Santaló has contributed to various areas of mathematics. His work has applications in number theory, in the theory of differential equations, in stochastic geometry, in functional analysis, and also in theoretical physics. Between the 1950’s and the 1970’s, he wrote a series of papers on general relativity and on the attempts at generalizing Einstein’s theory to formulate a unified field theory. His main contribution in this subject was to provide a classification theorem for the plethora of tensors that were populating Einstein’s generalized theory. This paper revisits his work on theoretical physics.

For some time, even after the Feynman diagrams and rules were publicly known, the foundations of Feynman’s quantum electrodynamics remained mostly private. Its stupendous efficiency then appeared like magic to most of his competitors. The purpose of this essay is to reveal the hidden contrivances of this magic, in a journey from field-less electrodynamics to the Feynman diagrams.

Neutrino beams obtained from proton accelerators were first operated in 1962. Since then, neutrino beams have been intensively used in particle physics and evolved in many different ways. We describe the characteristics of various neutrino beams, relating them to the historical development of the physics studies and discoveries. We also discuss some of the ideas still under consideration for future neutrino beams.

Since early models of wave propagation in both stationary and moving media during the nineteenth century, the Lorentz transformation (LT) has played a key role in describing characteristic wave phenomena, e.g., the Doppler shift effect. In these models LT connects two different events generated by wave propagations, as observed in two reference systems and the synchronism is absolute. In relativistic physics LT implements the relativity principle. As a consequence, it connects two space-time event coordinates that both correspond to the same physical event and “absolute synchronization” is not allowed. The relativistic interpretation started from Einstein’s early criticism of the notion of “simultaneity” and Minkowski’s invariance of the space-time interval. In this paper, the two different roles of LT, i.e., in classical wave propagation theories and in relativistic physics, are discussed. Einstein’s early criticism is also re-examined with respect to LT in view of its significance for the notion of simultaneity. Indeed, that early criticism is found to be defective. Our analysis is also useful for general readers in view of its impact on modern speculations about the existence of a preferred system of reference Σ, where light propagation is isotropic, and related implications.