The European Physical Journal H最新文献

The discovery of the Higgs boson in 2012 at CERN completed the experimental confirmation of the Standard Model particle spectrum. Current theoretical insights and experimental data are inconclusive concerning the expectation of future discoveries. While new physics may still be within reach of the LHC or one of its successor experiments, it is also possible that the mass of particles beyond those of the Standard Model is far beyond the energy reach of any conceivable particle collider. We thus have to face the possibility that the age of “on-shell discoveries” of new particles may belong to the past and that we may soon witness a change in the scientists' perception of discoveries in fundamental physics. This article discusses the relevance of this questioning and addresses some of its potential far-reaching implications through the development, first, of a historical perspective on the concept of particle. This view is prompt to reveal important specificities of the development of particle physics. In particular, it underlines the close relationship between the evolution of observational methods and the understanding of the very idea of particle. Combining this with an analysis of the current situation of high-energy physics, this leads us to the suggestion that the particle era in science must undergo an important conceptual reconfiguration.

We analyzed remarkable stories linked to the famous Anatoly Vlasov equations in plasma physics. Their creation, modification, and application are interesting from the scientific viewpoint. We also show the relations between those equations dealing with electromagnetism and analogous Jeans equations describing, in particular, gravitational instability in astrophysics. The second half of the essay is devoted to the controversies and political struggle in Soviet (before 1991) and Russian (after 1991) physical communities related to Vlasov’s personality, career, and posthumous recognition. The never-ending destructive influence of the Russian totalitarianism on science is demonstrated.

We present a translation of the 1933 paper by R. Fürth in which a profound analogy between quantum fluctuations and Brownian motion is pointed out. Fürth highlights the existence of uncertainty relations involving the variance of a statistically conserved quantity of a non-equilibrium thermodynamic indicator and the variance of the corresponding current velocity. The phenomenon is entirely classical and traces back to the effect of a fluctuating environment on a measured system. In some sense, Fürth’s paper also opened the way to the stochastic methods of quantization developed almost 30 years later by Edward Nelson and others.

The development and evolution of the “Einstein–Æther Theory” (Æ-theory) shows that there is a field in cosmology where the word ether is being used again. It is unclear, however, whether this æther may be regarded in continuation with previous ethers, or it is an altogether new entity. The main goal of this paper is to understand the nature of this new ether in the context of previous instances of this scientific object. In order to do so, we shall first give a brief historical account of the distinct uses the word had assumed in the late nineteenth and early twentieth centuries, before its demise. Then, we shall describe the major attempts to revive the ether over the last century, focusing on the last endeavor: the Æ-theory. In this article, we do not intend to support or reject this new use of the word, but to stress the complexity of establishing a consistent historical narrative of some scientific objects like the ether.

The nature of light, the existence of magnetism, and the physical meaning of a vacuum are the problems so deeply related to philosophy that they have been discussed for thousands of years. In this paper, we concentrate ourselves on a question that concerns the three of them: does light speed in a vacuum change when a magnetic field is present? The experimental answer to this fundamental question has not yet been given even if it has been stated in modern terms for more than a century. To fully understand the importance of such a question in physics, we review the main facts and concepts from the historical point of view.

The Inter-University Centre for Astronomy and Astrophysics (IUCAA) is the second Inter-University Centre established by the Government of India for promotion of astronomy and astrophysical research. In this article, the historical development, as well as the motivation, for establishing IUCAA has been discussed which comprises of the period 1988–1993, i.e. the first 5 years. A glimpse of research work in pre- and post-colonial era in India has also been presented to have a holistic view of the genesis.

The present year 2021 celebrates the 75th anniversary of the nuclear magnetic resonance method (NMR), which has had an immense importance for several branches of physics, chemistry and biology. The splitting of resonances and the shifts in their positions are seemingly inexhaustible sources of information for organic chemistry and biology. It was first introduced for the study of nuclear spins and their associated magnetic properties and when it was observed that resonance lines were broadened by the action of fluctuating local magnetic fields it was first seen as a limitation for the exact determination of nuclear properties. However, it was soon realized that the broadening contained important information on the dynamics of atoms, molecules or cooperative spin systems surrounding the nuclei and spin perturbations became a well-developed tool for investigation of internal dynamics in liquids and solids, over time-ranges from seconds down to femtoseconds. The present article is an attempt to review this latter line of development and to pick out a series of examples of internal dynamics in different physical systems published over the past 75 years. Examples include motions of particles in solids, magnetic resonance imaging (MRI), critical phenomena around phase transitions, functioning of biomolecules and recent applications to spintronics and quantum computing. Other spin-based spectroscopies followed in the tracks of NMR with use of electron spins (in electron spin resonance ESR also called electron paramagnetic resonance EPR, and ferromagnetic resonance, FMR), excited nuclear states (by observation of perturbations in angular correlation of gamma-rays, PAC) and later also muon spins (muon spin relaxation, MuSR), from which other examples are selected.

At the turn of the 1980s and 1990s, on the eve of the great leap in scale from the resonant bars to the long-baseline interferometers LIGO and Virgo, the four European groups then engaged in the field of interferometric gravitational wave detection in Germany, UK, France and Italy tried to set up a common strategy, with the aim of establishing a network of three long-based antennas in Europe. The paper analyzes the main causes of the failure of those early plans. An attempt is made to outline the parallels and differences with the current times, on the eve of the new leap of scale toward the third generation of gravitational wave interferometers, while the negotiations for the European-born project Einstein Telescope are taking place.

We carry out a detailed analysis of the contribution of the outstanding liquid crystal scientist Hans Zocher to the study of mineral mesophases. The work is placed in the context of progress achieved by the liquid crystal scientists, who conducted research both before and after Zocher. The article also includes a brief scientific biography of Zocher.

In this paper, we deal with the historical origins of Fermi–Dirac statistics, focusing on the contribution by Enrico Fermi of 1926. We argue that this statistics, as opposed to that of Bose–Einstein, has been somewhat overlooked in the usual accounts of the old quantum theory. Our main objective is to offer a critical analysis of Fermi’s seminal paper and its immediate impact. Secondly, we are also interested in assessing the status of the particle concept in the years 1926–1927, especially regarding the germ of quantum indistinguishability. We will see, for example, that the first applications of the Fermi–Dirac statistics to the study of metals or stellar matter had a technical nature, and that their main instigators barely touched upon interpretative matters. Finally, we will discuss the reflections and remarks made in these respects in two famous events in physics of 1927, the Como conference and the fifth Solvay congress.