The European Physical Journal H最新文献

This contribution aims to highlight the profoundly human aspects of Alessandro Serpieri’s personality, as emerge from the testimonies related to the teaching he practiced for his students and from his scientific writings; and to underline above all the particularities of his scientific vision in which an integral catholic faith permeates a very clear rationalist approach, thus preventing him from slipping towards past Enlightenment extremisms or towards the looming positivist materialism. From this point of view, Serpieri might be defined as an ancient rationalist, far away from the typical rationalism introduced by the Scholasticism in late Middle Ages and accepted ever since then from the Catholic Church. What emerges is the portrait of a multifaceted scientist, gifted with uncommon qualities. We will also recall some ideas, original for that time, which in the following decades and in particular in the second half of the twentieth century would find fruitful developments especially in the field of theoretical physics.

In 1947, four months before the famous Shelter Island conference, Richard Feynman wrote a lengthy letter to his former MIT classmate Theodore Welton, reporting on his efforts to develop a path integral describing the propagation of a Dirac particle. While these efforts never came to fruition, and were shortly abandoned in favor of a very different method of dealing with the electron propagator appearing in in QED, the letter is interesting both from the historical viewpoint of revealing what Feynman was thinking about during that period just before the development of QED, and for its scientific ideas. It also contains at the end some philosophical remarks, which Feynman wraps up with the comment, “Well enough for the baloney.” In this article I present a transcription of the letter along with editorial notes, and a facsimile of the original handwritten document. I also briefly comment on Feynman’s efforts and discuss their relation to some later work.

A personal recollection of early years in lattice gauge theory with a bias toward chiral symmetry and lattice fermions.

In 1969, the Russian Mathematical Survey published a paper by Felix A. Berezin called “THE PLANE ISING MODEL” (Berezin in Russ Math Surv 24:1, 1969) where Onsager’s solution of the two-dimensional Ising model is found by means of integrals over anticommuting variables (Grassmann variables). Berezin’s work provides a very elegant method for solving the Ising model which turns out to be much simpler if compared to previous methods. Berezin’s work represents also the very first use of anticommuting variables for solving actual combinatorial problems. Western literature, however, has ignored Ref. Berezin (Russ Math Surv 24:1, 1969). In fact, more than a decade after Berezin’s paper, S. Samuel re-found, independently, essentially the same solution obtained by Berezin, but with no reference to his work. S. Samuel solved also other planar models and paved the way to a subsequent proliferation of papers both related to statistical mechanics and fermionic field theories. Yet, we have verified that, until now, western literature still does not cite the original work of Berezin on the Ising model. The aim of this perspective paper is to fix this chronic issue and contextualize it within the unfortunate biographical and historical facts around Berezin’s life.

There were at least seven attempts to calculate critical radii for reactors or bombs 1939–1945. Those made by Flügge and Peierls in 1939 are compared with the calculations made by Perrin (1939), Heisenberg (1939 and 1945) and Serber (1943). Fermi’s 1942 reactor calculations are not covered here because that would call for a separate paper. Heisenberg calculated the critical radius formula and some critical radii in 1939 for a reactor. He focused on reactors 1939–45 and apparently did not make a bomb calculation before his August 1945 Farm Hall Lecture where he independently reproduced the 1943 Los Alamos Primer calculation for a bomb to within the limits that he knew the fast fission cross section. Flügge attempted a ponderous alternative to a critical radius calculation. Perrin’s calculation predates the Heisenberg and Serber calculations. His theoretical choice of tamper boundary condition was not optimal but his calculation method was correct. Peierls aimed to improve on Perrin's method but did worse. Finally, we calculate the 2.1 cm critical radius stated in the Frisch–Peierls Memorandum from Peierls’ model and graph, and we also show how Frisch and Peierls likely calculated it, including why Frisch assumed a fission cross section of 10 barn in his calculation.

How was Lattice Gauge Theory born? What was it like in the “early days” of the 1970s and 80s before lattice field theory became a substantial subfield of high energy theory? How did high energy physics and condensed matter theory get together? What were the big physics problems and technical challenges of the day? This short talk looks at these topics from one person’s personal recollections, experiences and perspective.

Raoul Gatto and Bruno Touschek’s collaboration in the establishment of electron–positron colliders as a fundamental discovery tool in particle physics will be illustrated. In particular, we will tell the little-known story of how Gatto and Touschek’s pioneering visions combined to provide the theoretical foundation for AdA, the first matter–antimatter collider, and how their friendship with Wolfgang Pauli and Gerhard Lüders was crucial to their understanding of the CPT theorem, the basis for AdA’s success. We will see how these two exceptional scientists shaped physics between Rome and Frascati, from the proposal to build AdA and soon after the larger machine ADONE in 1961, to the discovery of the (J/Psi ) particle in 1974. We will also highlight Gatto and Touschek’s contribution in mentoring an extraordinary cohort of students and collaborators whose work contributed to the renaissance of Italian theoretical physics after the Second World War and to the establishment of the Standard Model of particle physics.

The concepts of radiative and adiabatic equilibria, introduced by Karl Schwarzschild in his seminal paper Ueber das Gleichgewicht der Sonnenatmosphäre published in January 1906, are the founding blocks of the theory of radiative transfer, stellar structure, and solar physics. Careful reading of the paper and its later English translation reveals small formal inaccuracies and ambiguities but with no consequences whatsoever for the final outcomes and conclusions. This paper offers their adjustments with respective derivations using contemporary formalism and sets Schwarzschild’s paper in context with a historical and modern perspective. Particular attention is paid to Schwarzschild’s largely forgotten limb-darkening formula for adiabatic equilibrium. The paper also reproduces Schwarzschild’s radiative equilibrium protomodel of the Sun’s atmosphere in graphical form and compares it with modern models presented in some of the most cited papers in stellar and solar physics.