Highlighted Papers

This page presents Highlights of published articles selected on the basis of the quality of their scientific achievements and potential wider impact. The PDF of these highlighted papers can be downloaded freely for two months from the publication of the Highlight.

April 2011
EPJ H - Cosmic Rays: a (partly) untold story

The work behind the discovery of cosmic rays, a milestone in science, involved many scientists in Europe and the New World fascinated by the puzzling penetrating radiation, and took place during a period characterized by lack of communication and by nationalism caused primarily by World War I. It took eventually from the turn of the century until 1926 before the extraterrestrial nature of the penetrating radiation was generally accepted.
In the work that culminated with high altitude balloon flights, many important contributions have been forgotten and in particular those of Domenico Pacini, who, in June 1911, demonstrated by studying the decrease of radioactivity with an electroscope immersed in water that the radiation today called "cosmic rays" could not come from the crust of the Earth. This was the first time in which the technique of comparison of undersea measurements with measurements at sea level has been used to obtain a result in fundamental physics; this technique will be used in neutrino experiments of the near future.
This article carefully retraces the history of the discovery of cosmic rays and puts the unfolding story in both the political and scientific contexts. With the help of material previously unknown to the history of science, for example the nominations for the Nobel prizes related to cosmic ray research and the relevant internal reports of the Swedish Royal Academy of Science, and letters exchanged between Victor Hess and Pacini, a more complete view of this fascinating discovery is possible .
[Nationalism and internationalism in science: the case of the discovery of cosmic rays by P. Carlson and A. De Angelis, Eur. Phys. J. H 36, 309-329 (2010), DOI: 10.1140/epjh/e2011-10033-6]

October 2010
Long-time behavior of macroscopic quantum systems - Commentary accompanying the English translation of John von Neumann’s 1929 article on the quantum ergodic theorem
The renewed interest in the foundations of quantum statistical mechanics in recent years has led us to study John von Neumann's 1929 article on the quantum ergodic theorem (QET). We have found this almost forgotten article, which until now has been available only in German, to be a treasure chest, to be much misunderstood and very relevant to the recent discussion on the general and abstract reasons why, and the exact sense in which, an isolated macroscopic quantum system will approach thermal equilibrium from (more or less) any initial state. In his paper, von Neumann studied the long-time behavior of macroscopic quantum systems. His main result, the QET, expresses so-called "normal typicality": for a typical finite family of commuting macroscopic observables, every initial wave function ψ(0) from a micro-canonical energy shell so evolves that for most times t in the long run, the joint probability distribution of these observables obtained from ψ(t) is close to their micro-canonical distribution.
In our commentary, we provide a gentle introduction to the QET and discuss its relevance to the approach to thermal equilibrium. There is, in fact, no consensus about the definition of thermal equilibrium for a quantum (or even a classical) system in microscopic terms; the main divide in the literature lies between the "ensemblists" who regard thermal equilibrium as a property of an ensemble (or a mixed state) and the "individualists" who regard thermal equilibrium as a property of an individual system (in a pure state). As we explain, von Neumann's concept of equilibrium is influenced by both views but mainly based on the individualist view, a view that has gained ground recently.
[Long-time behavior of macroscopic quantum systems by S. Goldstein, J. L. Lebowitz, R. Tumulka and N. Zanghì, Eur. Phys. J. H 35, 173-200 (2010), DOI: 10.1140/epjh/e2010-00007-7]