The Politics of Memory: Otto Hahn and the Third Reich

As President of the Kaiser Wilhelm Society and its successor, the Max Planck Society, from 1946 until 1960, Otto Hahn (1879–1968) sought to portray science under the Third Reich as a purely intellectual endeavor untainted by National Socialism. I outline Hahn’s activities from 1933 into the postwar years, focusing on the contrast between his personal stance during the National Socialist period, when he distinguished himself as an upright non-Nazi, and his postwar attitude, which was characterized by suppression and denial of Germany’s recent past. Particular examples include Hahn’s efforts to help Jewish friends; his testimony for colleagues involved in denazification and on trial in Nuremberg; his postwar relationships with émigré colleagues, including Lise Meitner; and his misrepresentation of his wartime work in the Kaiser Wilhelm Institute for Chemistry.     

Otto Hahn: Responsibility and Repression

The role that Otto Hahn (1879–1968) played in the discovery of nuclear fission and whether Lise Meitner (1878–1968) should have shared the Nobel Prize for that discovery have been subjects of earlier studies, but there is more to the story. I examine what Hahn and the scientists in his Kaiser Wilhelm Institute for Chemistry in Berlin-Dahlem did during the Third Reich, in particular, the significant contributions they made to the German uranium project during the Second World War. I then use this as a basis for judging Hahn’s postwar apologia as the last president of the Kaiser Wilhelm Society and first president of its successor, the Max Planck Society.     

An Inconvenient History: the Nuclear-Fission Display in the Deutsches Museum

One of the longstanding attractions of the Deutsches Museum in Munich, Germany, has been its display of the apparatus associated with the discovery of nuclear fission. Although the discovery involved three scientists, Otto Hahn, Lise Meitner, and Fritz Strassmann, the fission display was designated for over 30 years as the Arbeitstisch von Otto Hahn (Otto Hahn’s Worktable), with Strassmann mentioned peripherally and Meitner not at all, and it was not until the early 1990s that the display was revised to include all three codiscoverers more equitably. I examine the creation of the fission display in the context of the postwar German culture of silencing the National Socialist past, and trace the eventual transformation of the display into a contemporary exhibit that more accurately represents the scientific history of the fission discovery.     

Studies of light-charged particle emission in fission at Trombay

Studies of prompt radiations emitted in fission were started at Trombay in the late 1950’s by Dr R Ramanna and over the years extensive investigations on the emission of prompt neutrons, gamma ray and K x-rays in fission were carried out with neutron beams fromapsara andcirus reactors. In the early 1960’s studies on the emission of light-charged particles in fission, which is a rare mode of fission, were also started. This paper reviews some of the recent studies on the emission of light-charged particles (lcp) in fission which were carried out with a view to investigate the mechanism oflcp emission, the scission configuration and the dynamics of the last stages of the fission process.     

Majorana: From Atomic and Molecular, to Nuclear Physics

In the centennial of Ettore Majorana’s birth (1906–1938?), we re-examine some aspects of his fundamental scientific production in atomic and molecular physics, including a not well known short communication. There, Majorana critically discusses Fermi’s solution of the celebrated Thomas–Fermi equation for electron screening in atoms and positive ions. We argue that some of Majorana’s seminal contributions in molecular physics already prelude to the idea of exchange interactions (or Heisenberg–Majorana forces) in his later works on theoretical nuclear physics. In all his papers, he tended to emphasize the symmetries at the basis of a physical problem, as well as the limitations, rather than the advantages, of the approximations of the method employed.     

Poincaré’s Relativistic Physics: Its Origins and Nature

Henri Poincaré (1854–1912) developed a relativistic physics by elevating the empirical inability to detect absolute motion, or motion relative to the ether, to the principle of relativity, and its mathematics ensured that it would be compatible with that principle. Although Poincaré’s aim and theory were similar to those of Albert Einstein (1879–1955) in creating his special theory of relativity, Poincaré’s relativistic physics should not be seen as an attempt to achieve Einstein’s theory but as an independent endeavor. Poincaré was led to advance the principle of relativity as a consequence of his reflections on late nineteenth-century electrodynamics; of his conviction that physics should be formulated as a physics of principles; of his conventionalistic arguments on the nature of time and its measurement; and of his knowledge of the experimental failure to detect absolute motion. The nonrelativistic theory of electrodynamics of Hendrik A.Lorentz (1853–1928) of 1904 provided the means for Poincaré to elaborate a relativistic physics that embraced all known physical forces, including that of gravitation. Poincaré did not assume any dynamical explanation of the Lorentz transformation, which followed from the principle of relativity, and he did not seek to dismiss classical concepts, such as that of the ether, in his new relativistic physics. Shaul Katzir teaches in the Graduate Program in History and Philosophy of Science, Bar Ilan University.     

Infinity and Newton’s Three Laws of Motion

It is shown that the following three common understandings of Newton’s laws of motion do not hold for systems of infinitely many components. First, Newton’s third law, or the law of action and reaction, is universally believed to imply that the total sum of internal forces in a system is always zero. Several examples are presented to show that this belief fails to hold for infinite systems. Second, two of these examples are of an infinitely divisible continuous body with finite mass and volume such that the sum of all the internal forces in the body is not zero and the body accelerates due to this non-null net internal force. So the two examples also demonstrate the breakdown of the common understanding that according to Newton’s laws a body under no external force does not accelerate. Finally, these examples also make it clear that the expression ‘impressed force’ in Newton’s formulations of his first and second laws should be understood not as ‘external force’ but as ‘exerted force’ which is the sum of all the internal and external forces acting on a given body, if the body is infinitely divisible.     

Quirino Majorana’s Experiments on the Speed of Light and Gravitational Absorption

Quirino Majorana (1871–1957) was an outstanding Italian experimental physicist who investigated a wide range of phenomena during his long career in Rome,Turin, and Bologna. We focus on his experiments in Turin during 1916–1921 and in Bologna during 1921–1934 to test the validity of Albert Einstein’s postulate on the constancy of the speed of light and to detect gravitational absorption. These experiments required extraordinary skill, patience, and dedication, and all of them confirmed Einstein’s postulate and Isaac Newton’s law of universal gravitation to high precision. Had they not done so, Majorana’s fame among historians and physicists no doubt would be much greater than it is today. Giorgio Dragoni is Professor of History of Physics at the University of Bologna. Giulio Maltese is a Roman member of the Italian Society for the History of Physics and Astronomy. Luisa Atti is a Bolognese member of the Association for the Teaching of Physics.     

Paul Ehrenfest’s Rough Road to Leiden: A Physicist’s Search for a Position, 1904–1912

Paul Ehrenfest (1880–1933) received his Ph.D. degree at the University of Vienna in 1904 and moved with his wife and young daughter to St. Petersburg in 1907, where he remained until he succeeded Hendrik Antoon Lorentz (1853–1928) in the chair of theoretical physics at the University of Leiden in 1912. Drawing upon Ehrenfest’s correspondence of the period, we first examine Ehrenfest’s difficult and insecure years in St. Petersburg and then discuss his unsuccessful attempts to obtain a position elsewhere before he was appointed as Lorentz’s successor in Leiden. Pim Huijnen is writing a doctoral dissertation in history; the present paper is based upon his Master’s Thesis, “‘Die Grenze des Pathologischen’: Het leven van fysicus Paul Ehrenfest, 1904–1912,” University of Groningen, 2003. A.J.Kox is Pieter Zeeman Professor of History of Physics at the University of Amsterdam.     

A Conversation with Valentine L.Telegdi – Part II

In this wide-ranging and anecdotal interview, the Hungarian experimental physicist Valentine L. Telegdi, who died on April 8, 2006, offers recollections of Enrico Fermi and Gregor Wentzel in the early 1950s at the University of Chicago. He recalls the discovery of quarks in 1963 independently by Murray Gell-Mann at Caltech and George Zweig at CERN. Comments on the establishment of the Erice summer school. Describes his work on the anomalous magnetic moment of the muon (the “g-minus-2” experiment) with Richard Garwin at CERN. Recalls the colloquium given at the ETH (the Swiss Federal Institute of Technology) in the late 1940s by Richard Feynman. Recalls his 1956 sabbatical at the Institute for Advanced Study; recollections of John Archibald Wheeler. Comments on the decline of physics at the University of Chicago after Fermi’s death (1954) and the switchover from liberal military funding to the more cumbersome NSF grants process; contrasts that with the generosity of the ETH. Comments on his early days at Chicago and his longstanding friendship with Murph [Marvin L.] and Mildred Goldberger. Recalls his three-month stay at Bristol University in 1947 while still a graduate student at ETH and his friendship with Richard Dalitz. Comments on Stephen Hawking. Recollections of P.A.M.Dirac.Comments on Jerome Friedman, Richard Taylor,and Henry Kendall; on Nobel Prizes and the reason for Arnold Sommerfeld’s failure to receive one. Recalls receiving the Wolf Prize in 1991 (along with Maurice Goldhaber) and an honorary degree the same year from the University of Chicago.     

Enrico Fermi’s Discovery of Neutron-Induced Artificial Radioactivity:The Influence of His Theory of Beta Decay

We analyze the influence of Enrico Fermi’s theory of beta decay, which he formulated in December 1933, on his experimental discovery of neutron-induced artificial radioactivity four months later, in March 1934.We discuss Gian Carlo Wick’s application of Fermi’s theory in interpreting Frédéric Joliot and Irène Curie’s discovery of alpha-particle-induced artificial radioactivity, and how Fermi was then influenced by his theory in planning his neutron-bombardment experiments, in his decision to use a radon-beryllium (Rn-Be) neutron source, and in his choice of the elements he bombarded with Rn-Be neutrons. Our analysis is based crucially on Fermi’s first laboratory notebook, the Hirpine Notebook, which is preserved in the Oscar D’Agostino Archives in the Technical Institute “Oscar D’Agostino” in Avellino, Italy, and on the materials that are preserved in the Fermi Archives in the Domus Galilaeana in Pisa. These documents enable us to reconstruct Fermi’s discovery of neutron-induced artificial radioactivity and to assign an exact date to it of March 20, 1934.     

Ettore Majorana’s Forgotten Publication on the Thomas-Fermi Model

We analyze the forgotten communication of Ettore Majorana (1906–1938?) on the Thomas-Fermi statistical model of the atom, which he presented on December 29, 1928, during the XXII General Meeting of the Italian Physical Society in Rome, and which was published in Il Nuovo Cimento, the Society’s journal, in 1929. His communication was not mentioned subsequently in any of the numerous publications of Enrico Fermi (1901–1954) and his group in Rome, nor in any of the later accounts of Majorana’s life and work. We place Majorana’s contribution within the context of contemporary research on the subject, point out its influence on the final formulation of the Thomas-Fermi statistical model by Fermi and Edoardo Amaldi (1908–1989) in 1934, and discuss Majorana’s other scientific contributions before his mysterious disappearance in 1938. Francesco Guerra is Professor of Theoretical Physics in the Department of Physics at the University of Rome “La Sapienza.” His main fields of research are quantum-field theory, statistical mechanics of complex systems, and the history of nuclear physics. Nadia Robotti is Professor of History of Physics in the Department of Physics at the University of Genoa. Her main fields of research are the history of atomic physics, quantum mechanics, and nuclear physics.     

In Memoriam

In 1905 Lord Kelvin (1824–1907) was awarded the second John Fritz Medal for a lifetime of outstanding achievements in science and technology. I sketch Kelvin’s life, education, and work in thermodynamics, electrical technology, and instrumentation, and his role in the laying of the Atlantic cable. I then turn to Kelvin’s four visits to America, in 1876 on the centenary of the Declaration of Independence of the United States of America; in 1884 when he gave his famous Baltimore Lectures at The Johns Hopkins University; in 1897 when he visited Niagara Falls for the third time and advised George Westinghouse (1846–1914) on how to develop its enormous water power for the generation of electricity; and in 1902 when he advised George Eastman (1854–1932) on the development of the photographic industry. Written in connection with the Kelvin Centenary Year 2007; see “Celebrating the Life of Lord Kelvin,” University of Glasgow News Review No. 11 (2007), 4. Matthew Trainer: Matthew Trainer received his M.Phil. degree in physical sciences at the University of Edinburgh in 1980 and currently is a laboratory instructor at the University of Glasgow where his research focuses in part on the life and work of Lord Kelvin.     

In Appreciation

Leslie Foldy’s diminutive stature and modest demeanor gave little clue to the powerful intellect responsible for several significant advances in theoretical physics.Two were particularly important. His 1945 theory of the multiple scattering of waves laid out the fundamentals that most modern theories have followed (and sometimes rediscovered), while his work with Siegfried Wouthuysen on the nonrelativistic limit of the Dirac equation opened the way to a wealth of valuable insights. In this article we recall some of the milestones along Foldy’s path through a life in physics. Some of the anecdotes we report here were related to one of the authors (PLT) just before an event in 2000 celebrating Foldy’s 80th birthday, while others were told to us over the course of the nearly forty years during which we were colleagues. Still others were uncovered during the course of WJF’s research for his book, Physics at a Research University: Case Western Reserve 1830–1990 (Cleveland: Case Western Reserve University, 2006). Other details were provided by Foldy’s widow, Roma. Philip L. Taylor is the Perkins Professor of Physics and Professor of Macromolecular Science and Engineering at Case Western Reserve University. William J. Fickinger is Professor Emeritus of Physics at Case Western Reserve University.     

Einstein’s “Zur Elektrodynamik...” (1905) Revisited, With Some Consequences

Einstein, in his “Zur Elektrodynamik bewegter K?rper”, gave a physical (operational) meaning to “time” of a remote event in describing “motion” by introducing the concept of “synchronous stationary clocks located at different places”. But with regard to “place” in describing motion, he assumed without analysis the concept of a system of co-ordinates.In the present paper, we propose a way of giving physical (operational) meaning to the concepts of “place” and “co-ordinate system”, and show how the observer can define both the place and time of a remote event. Following Einstein, we consider another system “in uniform motion of translation relatively to the former”. Without assuming “the properties of homogeneity which we attribute to space and time”, we show that the definitions of space and time in the two systems are linearly related. We deduce some novel consequences of our approach regarding faster-than-light observers and particles, “one-way” and “two-way” velocities of light, symmetry, the “group property” of inertial reference frames, length contraction and time dilatation, and the “twin paradox”. Finally, we point out a flaw in Einstein’s argument in the “Electrodynamical Part” of his paper and show that the Lorentz force formula and Einstein’s formula for transformation of field quantities are mutually consistent. We show that for faster-than-light bodies, a simple modification of Planck’s formula for mass suffices. (Except for the reference to Planck’s formula, we restrict ourselves to Physics of 1905.)     

On Visibility in the Afshar Two-Slit Experiment

A modified version of Young’s experiment by Shahriar Afshar indirectly reveals the presence of a fully articulated interference pattern prior to the post-selection of a particle in a “which-slit” basis. While this experiment does not constitute a violation of Bohr’s Complementarity Principle as claimed by Afshar, both he and many of his critics incorrectly assume that a commonly used relationship between visibility parameter V and “which-way” parameter K has crucial relevance to his experiment. It is argued here that this relationship does not apply to this experimental situation and that it is wrong to make any use of it in support of claims for or against the bearing of this experiment on Complementarity.     

The Nineteenth-Century Spiral Nebula Whodunit

The discovery of the first spiral nebula was a milestone in the history of astronomy, but the initial observations of it are shrouded in mystery. The discovery came within months of the commissioning of the Third Earl of Rosse’s very large 72-inch optical telescope at Birr Castle in the center of Ireland. Unfortunately, no observing records have survived, and while there is no doubt that the observations took place in the spring of 1845, there is some uncertainty as to whom was actually present when the discovery was made. The construction of the Earl’s telescope (the Leviathan) was a magnificent achievement, since it was entirely of his design, built with his own funds, and constructed by his own workers who were literally taken “from the plough” on his estate. The summer of 1845 saw the first appearance of the Irish Potato Famine of 1845–1848, which would seriously curtail astronomical activity when Lord Rosse’s 72-inch telescope was in prime condition.     

Early Attempts to Detect the Neutrino at the Cavendish Laboratory

In the 1920s and early 1930s the Cavendish Laboratory in Cambridge was preeminent in experimental research on radioactivity and nuclear physics, with theoretical physics playing a subsidiary role in guiding, but not determining the course of experimental research. Soon after Wolfgang Pauli (1900–1958) proposed his neutrino hypothesis in 1930 to preserve conservation of energy and momentum in beta decay, experiments – the first of their kind – were carried out in the Cavendish Laboratory to detect Pauli’s elusive particle, but they were abandoned in 1936. I trace these early attempts and suggest reasons for their abandonment, which may contribute to an understanding of the complex way in which theoretical entities are accepted by physicists.     

A Conversation with Robert F. Christy – Part II

Robert F. Christy, Institute Professor of Theoretical Physics Emeritus at Caltech, recalls his wartime work at Los Alamos on the critical assembly for the plutonium bomb (“the Christy bomb”); the Alamogordo test, July 16, 1945; the postwar concerns of ALAS (Association of Los Alamos Scientists); his brief return to the University of Chicago and move to Caltech; friendship with and later alienation from Edward Teller; work with Charles and Tommy Lauritsen and William A. Fowler in Caltech’s Kellogg Radiation Laboratory; Freeman Dyson’s Orion Project; work on the meson and RR Lyrae stars; fellowship at Cambridge University; 1950s Vista Project at Caltech; his opposition to the Strategic Defense Initiative; and his post-retirement work for the National Research Council’s Committee on Dosimetry and on inertial-confinement fusion.