Alwyn Van Der Merwe - Böcker

This 1984 book brings together 48 studies and essays written by physicists from around the world to mark the 90th birthday of Louis de Broglie and the 80th birthdays of Paul Dirac and Eugene Wigner. Publication under one cover of studies based on the discoveries of scientific personalities as diverse as those to whom this volume is dedicated serves at least one important purpose: it concretely reflects the rival pathways in quantum physics at the time of this book's publication. From one perspective, the papers contrast the strategies of a champion of the mathematical approach (Wigner) with those of a thinker who relied on physical intuition (de Broglie). From another, they compare the views of a defender (Wigner) and and opponent of the Copenhagen school (de Broglie), as well as those of an individual who helped to reconstruct the prevailing quantal paradigm, only later to advocate a return to causality (Dirac).

The forty papers collected here honor one of the great scientists of our time--John Archibald Wheeler. In this volume are gathered the six issues of the journal Foundations of Physics (February through July 1986) that celebrate his seventy-fifth birthday. Enlivened by Professor Wheeler's celebrated drawings, the book captures and illuminates his many contributions to physics, including his discovery of the scattering matrix and his elucidation, with Niels Bohr, of the mechanism of nuclear fission, his many contributions to Einstein's theory of gravity (for instance, the black hole), his deep insights into quantum theory and measurement (the elementary quantum phenomenon), and his efforts to explain the origins of the quantum postulate and quantum gravity (the meaning circuit and the Wheeler-DeWitt Equation). The majority of the papers reflect and build on Professor Wheeler's revolutionary ideas. Many scientists are convinced that his insights into the foundation of modern-day physics will induce a profound change in our perception of the universe.This book will appeal to scientists and philosophers who wish to look at one man's rendering of the "big picture" through the eyes of his colleagues. The work is prefaced by a compilation of quotes from Professor Wheeler, edited by Kip S. Thorne and Wojciech Zurek. The contributors to Between Quantum and Cosmos are M. Alexander, A. Anderson, H. H. Barschall, J. D. Bekenstein, C. H. Bennett, P. G. Bergmann, V. B. Braginsky, D. R. Brill, L. Brown, I. Ciufolini, L. Cohen, M. Demianski, D. Deutsch, B. DeWitt, C. DeWitt-Morette, R. H. Dicke, B. d'Espagnat, R. P. Feynman, J. Geheniau, U. H. Gerlach, R. Geroch, J. Glimm, J. B. Hartle, F. W. Hehl, M. Henneaux, P. A. Hogan, S. Hojman, J. Isenberg, F. Ya. Khalili, A. Kheyfets, K. V. Kuchar, R. Landauer, S. G. Low, V. N. Lukash, B. Mashhoon, R. A. Matzner, J. D. McCrea, A. Mezzacappa, W. A. Miller, Y. Ne'eman, I. D. Novikov, A. Peres, I. Prigogine, I. Robinson, L. S. Schulman, M. O. Scully, D. H. Sharp, L. C. Shepley, A. Y. Shiekh, C. Teitelboim, E. Teller, K. S. Thorne, W. G. Unruh, R. M. Wald, L. Wilets, W. K. Wootters, J. W. York, Jr., and W. H. Zurek. Originally published in 1988.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

The forty papers collected here honor one of the great scientists of our time--John Archibald Wheeler. In this volume are gathered the six issues of the journal Foundations of Physics (February through July 1986) that celebrate his seventy-fifth birthday. Enlivened by Professor Wheeler's celebrated drawings, the book captures and illuminates his many contributions to physics, including his discovery of the scattering matrix and his elucidation, with Niels Bohr, of the mechanism of nuclear fission, his many contributions to Einstein's theory of gravity (for instance, the black hole), his deep insights into quantum theory and measurement (the elementary quantum phenomenon), and his efforts to explain the origins of the quantum postulate and quantum gravity (the meaning circuit and the Wheeler-DeWitt Equation). The majority of the papers reflect and build on Professor Wheeler's revolutionary ideas. Many scientists are convinced that his insights into the foundation of modern-day physics will induce a profound change in our perception of the universe.This book will appeal to scientists and philosophers who wish to look at one man's rendering of the "big picture" through the eyes of his colleagues. The work is prefaced by a compilation of quotes from Professor Wheeler, edited by Kip S. Thorne and Wojciech Zurek. The contributors to Between Quantum and Cosmos are M. Alexander, A. Anderson, H. H. Barschall, J. D. Bekenstein, C. H. Bennett, P. G. Bergmann, V. B. Braginsky, D. R. Brill, L. Brown, I. Ciufolini, L. Cohen, M. Demianski, D. Deutsch, B. DeWitt, C. DeWitt-Morette, R. H. Dicke, B. d'Espagnat, R. P. Feynman, J. Geheniau, U. H. Gerlach, R. Geroch, J. Glimm, J. B. Hartle, F. W. Hehl, M. Henneaux, P. A. Hogan, S. Hojman, J. Isenberg, F. Ya. Khalili, A. Kheyfets, K. V. Kuchar, R. Landauer, S. G. Low, V. N. Lukash, B. Mashhoon, R. A. Matzner, J. D. McCrea, A. Mezzacappa, W. A. Miller, Y. Ne'eman, I. D. Novikov, A. Peres, I. Prigogine, I. Robinson, L. S. Schulman, M. O. Scully, D. H. Sharp, L. C. Shepley, A. Y. Shiekh, C. Teitelboim, E. Teller, K. S. Thorne, W. G. Unruh, R. M. Wald, L. Wilets, W. K. Wootters, J. W. York, Jr., and W. H. Zurek. Originally published in 1988.The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

Although the debate about the true nature of the quantum behavior of atomic systems has never ceased, there are two periods during which it has been particularly intense: the years that saw the founding of quantum mechanics and, increasingly, these modern times. In 1954 Max Born, on accepting the Nobel Prize for his 'fundamental researches in quantum mechanics', recalled the depth of the disagreements that divided celebrated quantum theorists of those days into two camps: . . . when I say that physicists had accepted the way of thinking developed by us at that time, r am not quite correct: there are a few most noteworthy exceptions - namely, among those very workers who have contributed most to the building up of quantum theory. Planck himself belonged to the sceptics until his death. Einstein, de Broglie, and Schriidinger have not ceased to emphasize the unsatisfactory features of quantum mechanics . . . . This dramatic disagreement centered around some of the most funda­ mental questions in all of science: Do atomic objects exist il1dependently of human observations and, if so, is it possible for man to understand correctly their behavior? By and large, it can be said that the Copenhagen and Gottingen schools - led by Bohr, Heisenberg, and Born, in particula- gave more or less openly pessimistic answers to these questions.

For many physicists quantum theory contains strong conceptual difficulties, while for others the apparent conclusions about the reality of our physical world and the ways in which we discover that reality remain philosophically unacceptable. This study focuses on recent theoretical and experimental developments in the foundations of quantum physics, including topics such as the puzzles and paradoxes which appear when general relativity and quantum mechanics are combined; the emergence of classical properties from quantum mechanics; stochastic electrodynamics; EPR experiments and Bell's Theorem; the consistent histories approach and the problem of datum uniqueness in quantum mechanics; non-local measurements and teleportation of quantum states; quantum non-demolition measurements in optics and matter wave properties observed by neutron, electron and atomic interferometry.

Quantum theory is one of the most fascinating and successful constructs in the intellectual history of mankind. Nonetheless, the theory has very shaky philosophical foundations. This book contains in-depth discussions of a spate of experimental techniques recently developed to test some of the stranger predictions of quantum physics. The advances considered include recent experiments in quantum optics, electron and ion interferometry, photon down conversion in nonlinear crystals, single trapped ions interacting with laser beams, atom-field coupling in micromaser cavities, quantum computation, quantum cryptography, decoherence and macroscopic quantum effects, the quantum state diffusion model, quantum gravity, the quantum mechanics of cosmology and quantum non-locality, along with the continuing debate surrounding the interpretation of quantum mechanics. The book is intended for physicists, philosophers of science, mathematicians, graduate students and those interested in the foundations of quantum theory.

The Centre pour la Synthese d'une Epistemologie Formalisee, henceforth briefly named CeSEF, was founded in June 1994 by a small group of s- entists working in various disciplines, with the definite aim to synthesize a "formalized epistemology" founded on the methods identifiable within the foremost modern scientificdisciplines. Most of the founders were already authors of well-known works displaying a particular sensitivity to episte- logical questions. But the aim that united us was new. This aim along with the peculiar choice of its verbal expression are thoroughly discussed in the Introduction. In the present volume, we publish the first harvest of explorations and constructive proposals advanced in pursuit of our goal. The contributions are expressive also of the views of those who shared only our beginnings and 1 then left us; they equally reflect input from those who participated in our workshops but did not contribute to this volume. We are indebted to the Association Naturalia et Biologica for having supported with a donation the publication of this volume. The camera-ready form of this book we owe to the patient and met- ulous labor of Ms. Jackie Gratrix.The superb job she has done is herewith gratefully acknowledged. Mioara Mugur-Schachter and Alwyn van der Merwe 1 Paul Bourgine and, quite specially, Bernard Walliser.

This work reveals the outstanding personality underlying Ettore Majorana's notes. A mixture of mathematical command, physics intuition and creative thought makes the Notes enjoyable for physicists of every discipline. The Notes are interesting for both graduate students and theoretical physics experts. In fact, the contents range from applied physics models, thorough fundamental atomic physics, to advanced group theory. The Notes have never been published and here they appear in the same format as organized by Ettore Majorana. The style is plain, proposed solutions to physics problems are original. These notes are intended as a series of fundamental physics themes treated by Ettore Majorana during the first "burning years" of the Panisperna Group, as the new deal of physics started in Rome around Enrico Fermi.

This book ushers in a new era of experimental and theoretical investigations into collective processes, structure formation, and self-organization of nuclear matter. It reports the results of experiments wherein for the first time the nuclei constituting our world (those displayed in Mendeleev's table as well as the super-heavy ones) have been artificially created. Pioneering breakthroughs are described, achieved at the "Proton-21" Laboratory, Kiev, Ukraine in a variety of new physical and technological directions.

Without listing his works, all of which are highly notable both for the originality of the methods utilized as well as for the importance of the results achieved, we limit ourselves to the following: Inmodernnucleartheories, thecontributionmadebythisresearcher to the introduction of the forces called ‘Majorana forces’ is universally recognized as the one, among the most fundamental, that permits us to theoretically comprehend the reasons for nuclear stability. The work of Majorana today serves as a basis for the most important research in this ?eld. In atomic physics, the merit of having resolved some of the most - tricate questions on the structure of spectra through simple and elegant considerations of symmetry is due to Majorana. Lastly, he devised a brilliant method that permits us to treat the positive and negative electron in a symmetrical way, ?nally elimin- ing the necessity to rely on the extremely arti?cial and unsatisfactory hypothesis of an in?nitely large electrical charge di?used in space, a question that had been tackled in vain by many other scholars [4].

0 e The selected popular writings contain articles he wrote on technical topics for such journals as The American Journal of Physics, Science, and Nature, as well as reflections on education, UFO's, and other topics.

From September 24 through 30, 1992 the Workshop on "Waves and Parti­ cles in Light and Matter" was held in the Italian city of Trani in celebration of the centenary of Louis de Broglie's birth. As is well known, the relationship between quantum theory and ob­ jective reality was one of the main threads running through the researches of this French physicist. It was therefore in a fitting tribute to him on his 90th birthday that ten years ago an international conference on the same subject was convened in Perugia. On that occasion, physicists from all over the world interested in the problematics of wave-particle duality engaged in thoughtful debates (the proceedings of which were subsequently published) on recent theoretical and experimental developments in our understanding of the foundations of quantum mechanics. This time around, about 120 scientists, coming from 5 continents, in the warm and pleasant atmosphere of Trani's Colonna Conference Center focussed their discussions on recent results concerned with the EPR para­ dox, matter-interferometry, reality of de Broglie's waves, photon detection, macroscopic quantum coherence, alternative theories to usual quantum mechanics, special relativity, state reduction, and other related topics. The workshop was organized in plenary sessions, round tables, and poster sessions, and the present volume collects most-but not all-of the presented papers. A number of acknowledgements are due. We thank, first of all, the contributors, without whose constant dedication this volume could not have been published.

E.U. Condon's major contributions were in atomic and molecular physics and spectroscopy; his book with G.H. Shortley on The Theory of Atomic Spectra dominated the field of spectroscopy for half a century and remains an invaluable reference. He also played an important role in the institutions of American science. He served for many years as the editor of Reviews of Modern Physics, and with Hugh Odishaw he edited the still widely used Handbook of Physics. After World War II, Condon became director of the National Bureau of Standards (now NIST), and helped to make it one of the premier research laboratories in the physical sciences in the world. The Selected Scientific Papers reprint many of the most important contributions Condon made to atomic physics, quantum theory, nuclear physics, condensed-matter physics and other fields. The Selected Popular Writings contain articles he wrote on technical topics for such journals as The American Journal of Physics, Science, and Nature, as well as reflections on education, UFO's, and other topics.

Simply to say that this is a collection of essays in honor of the late Wolfgang Yourgrau (1908-1979) is to explain, at least for-the obviously many-"insiders," the unusually wide-ranging title of the present volume. In a Foreword to the Proceedings of the First International Colloquium (focusing on logic, physical reality, and history), held at the University of Denver in May of 1966 under their leadership, Wolfgang Y ourgrau and Allen Breck wrote, in an oblique reference to C. P. Snow: "Indeed there are not two or three or four cultures: there is only one culture; our generation has lost its awareness of this . . . . Historians, logicians, physicists-all are banded in one common enterprise, namely in their des ire to weave an enlightened fabric of human knowledge. " Augment, if you will, the foregoing categories of scholars with biologists, philos­ ophers, cosmologists, and theologians-all of whom, in addition to historians, Wolf­ gang Yourgrau, by dint of his inextinguishable enthusiasm and charismatic qualities, assembled in Denver for the Second and Third International Colloquia (in 1967 and 1974, respectively)-and a few other besides, and one arrives at a statement of the credo wh ich Y ourgrau not only professed, but consistently exemplified throughout his adult life.

Due to its extraordinary predictive power and the great generality of its mathematical structure, quantum theory is able, at least in principle, to describe all the microscopic and macroscopic properties of the physical world, from the subatomic to the cosmological level. Nevertheless, ever since the Copen­ hagen and Gottingen schools in 1927 gave it the definitive formu­ lation, now commonly known as the orthodox interpretation, the theory has suffered from very serious logical and epistemologi­ cal problems. These shortcomings were immediately pointed out by some of the principal founders themselves of quantum theory, to wit, Planck, Einstein, Ehrenfest, Schrodinger, and de Broglie, and by the philosopher Karl Popper, who assumed a position of radical criticism with regard to the standard formulation of the theory. The aim of the participants in the workshop on Open Questions in Quantum Physics, which was held in Bari (Italy), in the Department of Physics of the University, during May 1983 and whose Proceedings are collected in the present volume, accord­ ingly was to discuss the formal, the physical and the epistemo­ logical difficulties of quantum theory in the light of recent crucial developments and to propose some possible resolutions of three basic conceptual dilemmas, which are posed respectively ~: (a) the physical developments of the Einstein-Podolsky-Rosen argument and Bell's theorem, i. e.

Theoretical physicists allover the world are acquainted with Lande's celebrated computation of the g factor or splitting factor or, more precisely, the magne­ togyric factor. The so-called anomalous Zeeman effect had intrigued, if not vexed, some of the most distinguished physicists of that time, such as Bohr, Sommerfeld, Pauli, and others. Lande realized that this recalcitrant effect was inseparable from the multiplet line structure - a breakthrough in understanding which he achieved in 1922 at the age of thirty four. It was in the same year that Lande discovered the interval rule for the separation of multiplet sublevels, a significant result that holds in all cases of Russell-Saunders coupling and renders comparatively easy the empirical analysis of spectral multiplets. In the twenties, Lande succeeded in constructing some original concepts of axiomatic thermodynamics by employing Caratheodory's somewhat esoteric approach as his guiding concept. Published in the Handbuch der Physik, his comprehensive treatise, evincing several novel ideas, has become a classic. Lande, Sommerfeld's student though never a true disciple, published two monographs on quantum mechanics that are remarkable for their content and exposition. In this connection it may be apposite to stress that Lande had sub­ scribed for many years to the (infelicitously named) Copenhagen interpretation.

Quantum mechanics has reached maturity as an a wesome scientific theory, and undeniably no experiment has so far produced any result conflic­ ting with its predictions. Nevertheless, an increasing number of scholars are seriously questioning the limits of this discipline's validity, a fact that is eloquently attested to by the four international conferences devoted to the foundations of quantum theory which were held in 1987 alone - in Joensuu, Vienna, Gdansk, and Delphi, respectively. There is an increa~ing awareness that the founding fathers of quantum mechanics have left behind a theory which, though spectacularly successful in its applications, severely limits our intuitive understanding of the microworld, and that their reasons for doing so were at least partly arbitrary and open to question. The problem of the relationship between the existing quantum theory and objective reality at the atomic and subatomic levels can be tackled in essentially two ways: (i) One may focus attention on the formalism of the theory and attempt to deduce from it a coherent description of our measuring processes and a deeper understanding of the microworld. Oi) Alternatively, one may start from the experimental evidence and/or from models of the objective reality compatible with it and go on to inves­ tigate whether or not formalization of this knowledge can be accomodated within the broad confines of existing quantum theory.

For many physicists quantum theory contains strong conceptual difficulties, while for others the apparent conclusions about the reality of our physical world and the ways in which we discover that reality remain philosophically unacceptable. This book focuses on recent theoretical and experimental developments in the foundations of quantum physics, including topics such as the puzzles and paradoxes which appear when general relativity and quantum mechanics are combined; the emergence of classical properties from quantum mechanics; stochastic electrodynamics; EPR experiments and Bell's Theorem; the consistent histories approach and the problem of datum uniqueness in quantum mechanics; non-local measurements and teleportation of quantum states; quantum non-demolition measurements in optics and matter wave properties observed by neutron, electron and atomic interferometry. Audience: This volume is intended for graduate students of physics and those interested in the foundations of quantum theory.

The Centre pour la Synthese d'une Epistemologie Formalisee, henceforth briefly named CeSEF, was founded in June 1994 by a small group of s- entists working in various disciplines, with the definite aim to synthesize a "formalized epistemology" founded on the methods identifiable within the foremost modern scientificdisciplines. Most of the founders were already authors of well-known works displaying a particular sensitivity to episte- logical questions. But the aim that united us was new. This aim along with the peculiar choice of its verbal expression are thoroughly discussed in the Introduction. In the present volume, we publish the first harvest of explorations and constructive proposals advanced in pursuit of our goal. The contributions are expressive also of the views of those who shared only our beginnings and 1 then left us; they equally reflect input from those who participated in our workshops but did not contribute to this volume. We are indebted to the Association Naturalia et Biologica for having supported with a donation the publication of this volume. The camera-ready form of this book we owe to the patient and met- ulous labor of Ms. Jackie Gratrix.The superb job she has done is herewith gratefully acknowledged. Mioara Mugur-Schachter and Alwyn van der Merwe 1 Paul Bourgine and, quite specially, Bernard Walliser.

This book is unique, since it reveals the outstanding personality underlying Majorana's notes. An extraordinary mixture of mathematical command, physics intuition and creative thought makes the Notes enjoyable for physicists of every discipline. The Notes are interesting for both graduate students and theoretical physics experts. In fact, the contents range from applied physics models, thorough fundamental atomic physics, to advanced group theory. The Notes have never been published and here they appear in the same format as organized by Ettore Majorana. The style is plain, proposed solutions to physics problems are original. These notes are intended as a series of fundamental physics themes treated by Ettore Majorana during the first "burning years" of the Panisperna Group, as the new deal of physics started in Rome around Enrico Fermi.

This book ushers in a new era of experimental and theoretical investigations into collective processes, structure formation, and self-organization of nuclear matter. It reports the results of experiments wherein for the first time the nuclei constituting our world (those displayed in Mendeleev's table as well as the super-heavy ones) have been artificially created. Pioneering breakthroughs are described, achieved at the "Proton-21" Laboratory, Kiev, Ukraine in a variety of new physical and technological directions.

Without listing his works, all of which are highly notable both for the originality of the methods utilized as well as for the importance of the results achieved, we limit ourselves to the following: Inmodernnucleartheories, thecontributionmadebythisresearcher to the introduction of the forces called ‘Majorana forces’ is universally recognized as the one, among the most fundamental, that permits us to theoretically comprehend the reasons for nuclear stability. The work of Majorana today serves as a basis for the most important research in this ?eld. In atomic physics, the merit of having resolved some of the most - tricate questions on the structure of spectra through simple and elegant considerations of symmetry is due to Majorana. Lastly, he devised a brilliant method that permits us to treat the positive and negative electron in a symmetrical way, ?nally elimin- ing the necessity to rely on the extremely arti?cial and unsatisfactory hypothesis of an in?nitely large electrical charge di?used in space, a question that had been tackled in vain by many other scholars [4].

Quantum theory is one of the most fascinating and successful constructs in the intellectual history of mankind. Nonetheless, the theory has very shaky philosophical foundations. This book contains thoughtful discussions by eminent researchers of a spate of experimental techniques newly developed to test some of the stranger predictions of quantum physics. The advances considered include recent experiments in quantum optics, electron and ion interferometry, photon down conversion in nonlinear crystals, single trapped ions interacting with laser beams, atom-field coupling in micromaser cavities, quantum computation, quantum cryptography, decoherence and macroscopic quantum effects, the quantum state diffusion model, quantum gravity, the quantum mechanics of cosmology and quantum non-locality along with the continuing debate surrounding the interpretation of quantum mechanics. Audience: The book is intended for physicists, philosophers of science, mathematicians, graduate students and those interested in the foundations of quantum theory.

Although the debate about the true nature of the quantum behavior of atomic systems has never ceased, there are two periods during which it has been particularly intense: the years that saw the founding of quantum mechanics and, increasingly, these modern times. In 1954 Max Born, on accepting the Nobel Prize for his 'fundamental researches in quantum mechanics', recalled the depth of the disagreements that divided celebrated quantum theorists of those days into two camps: . . . when I say that physicists had accepted the way of thinking developed by us at that time, r am not quite correct: there are a few most noteworthy exceptions - namely, among those very workers who have contributed most to the building up of quantum theory. Planck himself belonged to the sceptics until his death. Einstein, de Broglie, and Schriidinger have not ceased to emphasize the unsatisfactory features of quantum mechanics . . . . This dramatic disagreement centered around some of the most funda­ mental questions in all of science: Do atomic objects exist il1dependently of human observations and, if so, is it possible for man to understand correctly their behavior? By and large, it can be said that the Copenhagen and Gottingen schools - led by Bohr, Heisenberg, and Born, in particula- gave more or less openly pessimistic answers to these questions.

Quantum mechanics has reached maturity as an a wesome scientific theory, and undeniably no experiment has so far produced any result conflic­ ting with its predictions. Nevertheless, an increasing number of scholars are seriously questioning the limits of this discipline's validity, a fact that is eloquently attested to by the four international conferences devoted to the foundations of quantum theory which were held in 1987 alone - in Joensuu, Vienna, Gdansk, and Delphi, respectively. There is an increa~ing awareness that the founding fathers of quantum mechanics have left behind a theory which, though spectacularly successful in its applications, severely limits our intuitive understanding of the microworld, and that their reasons for doing so were at least partly arbitrary and open to question. The problem of the relationship between the existing quantum theory and objective reality at the atomic and subatomic levels can be tackled in essentially two ways: (i) One may focus attention on the formalism of the theory and attempt to deduce from it a coherent description of our measuring processes and a deeper understanding of the microworld. Oi) Alternatively, one may start from the experimental evidence and/or from models of the objective reality compatible with it and go on to inves­ tigate whether or not formalization of this knowledge can be accomodated within the broad confines of existing quantum theory.

For three days in April of 1985, Cesena (Italy) was the scene of a national conference which was convened, by the Assessorato alia Cultura of this town under the auspices of the Societa Italiana di Logica e Filosofia delle Scienze (SILFS), in order to celebrate two historical milestones: the centenary of the birth of Niels Bohr, who was to become the leader of the orthodox, or Copenhagen, interpretation of quantum theory, and the fiftieth anniversary of the publication of the most influential challenge to this interpretation which was contained in the well-known paper coauthored by Einstein, Podolsky, and Rosen. The proceedings of the Cesena meeting, which are collected in the present volume, are intended to provide an exhaustive and panoramic view of the most recent investigations carried out by Italian scientists and philo- sophers engaged in research on the foundations of quantum physics. What emerges is a critical review of, and alternative approaches to, the orthodox interpretation of the Copenhagen school.

Theoretical physicists allover the world are acquainted with Lande's celebrated computation of the g factor or splitting factor or, more precisely, the magne­ togyric factor. The so-called anomalous Zeeman effect had intrigued, if not vexed, some of the most distinguished physicists of that time, such as Bohr, Sommerfeld, Pauli, and others. Lande realized that this recalcitrant effect was inseparable from the multiplet line structure - a breakthrough in understanding which he achieved in 1922 at the age of thirty four. It was in the same year that Lande discovered the interval rule for the separation of multiplet sublevels, a significant result that holds in all cases of Russell-Saunders coupling and renders comparatively easy the empirical analysis of spectral multiplets. In the twenties, Lande succeeded in constructing some original concepts of axiomatic thermodynamics by employing Caratheodory's somewhat esoteric approach as his guiding concept. Published in the Handbuch der Physik, his comprehensive treatise, evincing several novel ideas, has become a classic. Lande, Sommerfeld's student though never a true disciple, published two monographs on quantum mechanics that are remarkable for their content and exposition. In this connection it may be apposite to stress that Lande had sub­ scribed for many years to the (infelicitously named) Copenhagen interpretation.