The bulk of the present book has not been published previously though Chapters II and IV are based in part on two earlier papers of mine: "The Influence of Harald H!1lffding's Philosophy on Niels Bohr's Interpretation of Quantum Mechanics", which appeared in Danish Yearbook of Philosophy, 1979, and "The Bohr-H!1lffding Relationship Reconsidered", published in Studies in History and Philosophy of Science, 1988. These two papers comple ment each other, and in order to give the whole issue a more extended (...) treatment I have sought, in the present volume by drawing on relevant historical material, to substantiate the claim that H!1lffding was Bohr's mentor. Besides containing a detailed account of Bohr's philosophy, the book, at the same time, serves the purpose of making H!1lffding' s ideas and historical significance better known to a non-Danish readership. During my work on this book I have consulted the Royal Danish Library; the National Archive of Denmark and the Niels Bohr Archive, Copenhagen, in search of relevant material. I am grateful for permission to use and quote material from these sources. Likewise, I am indebted to colleagues and friends for commenting upon the manuscript: I am especially grateful to Professor Henry Folse for our many discussions during my visit to New Orleans in November-December 1988 and again here in Elsinore in July 1990. (shrink)

Since the Niels Bohr centenary of 1985 there has been an astonishing international surge of scholarly analyses of Bohr's philosophy. Now for the first time in Niels Bohr and Contemporary Philosophy Jan Faye and Henry Folse have brought together sixteen of today's leading authors who have helped mould this new round of discussions on Bohr's philosophy. In fifteen entirely new, previously unpublished essays we discover a surprising variety of the different facets of Bohr as the natural philosopher whose (...) `framework of complementarity' shaped the final phase of the quantum revolution and influenced two generations of the century's leading physicists. There is much on which the authors included here agree; but there are also polar disagreements, which assure us that the philosophical questions revolving around Bohr's `new viewpoint' will continue to be a subject of scholarly interest and discussion for years to come. This collection will interest all serious students of history and philosophy of science, and foundations of physics. (shrink)

Steen Brock paints a cross-disciplinary picture of the philosophical and scientific background for the rise of the quantum theory. He accounts for the unity of Kantian metaphysics of Nature, the Helmholtzian principles, and the Hamiltonian methods of modern pre-quantum physics. Brock shows how Planck's vision of a generalization of classical physics implies that the original quantum mechanics of Heisenberg can be regarded as a successful attempt to maintain this modern unity of physics.However, for Niels Bohr, the unity of science (...) and metaphysics did not end in the world of physics. The development of quantum physics had general implications both for other sciences and for various philosophical issues. Brock discusses these matters with respect to recent topics within the philosophy of science and major interpretations of Bohr's ideas. The author invites the reader to follow a long andwinding route of thought which, in the end, culminates in Bohr's ideas of complementarity, culture and Spirit. (shrink)

It is well known that Niels Bohr insisted on the necessity of classical concepts in the account of quantum phenomena. But there is little consensus concerning his reasons, and what he exactly meant by this. In this paper, I re-examine Bohr’s interpretation of quantum mechanics, and argue that the necessity of the classical can be seen as part of his response to the measurement problem. More generally, I attempt to clarify Bohr’s view on the classical/quantum divide, arguing that the (...) relation between the two theories is that of mutual dependence. An important element in this clarification consists in distinguishing Bohr’s idea of the wave function as symbolic from both a purely epistemic and an ontological interpretation. Together with new evidence concerning Bohr’s conception of the wave function collapse, this sets his interpretation apart from both standard versions of the Copenhagen interpretation, and from some of the reconstructions of his view found in the literature. I conclude with a few remarks on how Bohr’s ideas make much sense also when modern developments in quantum gravity and early universe cosmology are taken into account. (shrink)

Niels Bohr and Philosophy of Physics: Twenty-First Century Perspectives examines the work, influences and legacy of the Nobel Prize physicist and philosopher of experiment Niels Bohr. While covering Bohr's groundbreaking contribution to quantum mechanics, this collection reveals the philosophers who influenced his work. Linking him to the pragmatist C.I. Lewis and the Danish philosopher Harald Høffding, it draws strong similarities between Bohr's philosophy and the Kantian way of thinking. Addressing the importance of Bohr's views of classical concepts, it (...) discusses how his interpretation of quantum mechanics now compares with a variety of issues that have arisen only since his lifetime, including decoherence and other non-collapse arguments. Balancing historical themes with contemporary ideas, Niels Bohrs and Philosophy of Physics reveals Bohr's on-going contribution to the philosophy of science and confirms his place in the history of philosophy. (shrink)

Of all the developments in twentieth century physics, none has given rise to more heated debates than the changes in our understanding of science precipitated by the quantum revolution''. In this revolution, Niels Bohr's dramatically non-classical theory of the atom proved to be the springboard from which the new atomic physics drew it's momentum. Furthermore, Bohr's contribution was crucial not only because his interpretation of quantum mechanics became the most widely accepted view but also because in his role as (...) educator and spokesman for atomic physics Bohr was very much the patron spirit of the entire quantum revolution. The conceptual framework which he proposed to provide a new viewpoint for understanding the quantum theoretical description of atomic systems became for most of this century the dominant outlook of countless productive experimental and theoretical physicists. He called this new framework complementarity''. (shrink)

Berichte zur Wissenschaftsgeschichte, EarlyView.

Murdoch describes the historical background of the physics from which Bohr's ideas grew; he traces the origins of his idea of complementarity and discusses its meaning and significance. Special emphasis is placed on the contrasting views of Einstein, and the great debate between Bohr and Einstein is thoroughly examined. Bohr's philosophy is revealed as being much more subtle, and more interesting than is generally acknowledged.

The book gives an painstaking analysis of Niels Bohr's understanding of quantum mechanics based on a claim that Bohr was influenced by Harald Høffding's approach to philosophical problems.

Niels Bohr began his career with an attempt to give a correct descriptive account of the motion of electrons. When forced to abandon this interpretation, he adopted, but soon rejected, a hypothetical-deductive account. In his development of an interpretation for the new quantum theory Bohr began to concentrate on the way language functions to make descriptions possible. His later work on this problem and on the role of concepts in the foundations of science led him to anticipate some of (...) the basic ideas developed in Wittgenstein's Investigations. Bohr eventually saw his own analysis of the conditions of the possibility of unambiguous communication as the basis for making explicit the unity implicit in science. (shrink)

Niels Bohr’s complementarity principle is a tenuous synthesis of seemingly discrepant theoretical approaches based on a comprehensive analysis of relevant experimental results. Yet the role of complementarity, and the experimentalist-minded approach behind it, were not confined to a provisional best-available synthesis of well-established experimental results alone. They were also pivotal in discovering and explaining the phenomenon of quantum tunneling in its various forms. The core principles of Bohr’s method and the ensuing complementarity account of quantum phenomena remain highly relevant (...) guidelines in the current controversial debate and in experimental work on quantum tunneling times. (shrink)

It has often been remarked that Bohr's writings on the interpretation of quantum mechanics make scant reference to the mathematical formalism of quantum theory; and it has not infrequently been suggested that this is another symptom of the general vagueness, obscurity and perhaps even incoherence of Bohr's ideas. Recent years have seen a reappreciation of Bohr, however. In this article we broadly follow this "rehabilitation program". We offer what we think is a simple and coherent reading of Bohr's statements about (...) the interpretation of quantum mechanics, basing ourselves on primary sources and making use of and filling lacunas in|recent secondary literature. We argue that Bohr's views on quantum mechanics are more firmly connected to the structure of the quantum formalism than usually acknowledged, even though Bohr's explicit use of this formalism remains on a rather global and qualitative level. In our reading, Bohr's pronouncements on the meaning of quantum mechanics should first of all be seen as responses to concrete physical problems, rather than as expressions of a preconceived philosophical doctrine. In our final section we attempt a more detailed comparison with the formalism and conclude that Bohr's interpretation is not far removed from present-day non-collapse interpretations of quantum mechanics. (shrink)

We clarify Bohr’s interpretation of quantum mechanics by demonstrating the central role played by his thesis that quantum theory is a rational generalization of classical mechanics. This thesis is essential for an adequate understanding of his insistence on the indispensability of classical concepts, his account of how the quantum formalism gets its meaning, and his belief that hidden variable interpretations are impossible.

The Copenhagen interpretation, which informs the textbook presentation of quantum mechanics, depends fundamentally on the notion of ontological wave-particle duality and a viewpoint called “complementarity.” In this paper, Bohr's own interpretation is traced in detail and is shown to be fundamentally different from and even opposed to the Copenhagen interpretation in virtually all its particulars. In particular, Bohr's interpretation avoids the ad hoc postulate of wave function ‘collapse' that is central to the Copenhagen interpretation. The strengths and weakness of both (...) interpretations are summarized. ‡I thank Edward Mackinnon, Henry Folse, and Greg Anderson for valuable comments on the penultimate draft. The final responsibility for the paper rests with the author. †To contact the author, please write to: Bhaktivedanta Institute, 2334 Stuart Street, Berkeley, CA; e-mail: [email protected]. I have been unable to achieve a sharp formulation of Bohr's principle of complementarity despite much effort I have expended on it. (Einstein 1949, 674) While imagining that I understand the position of Einstein, as regards the EPR correlations, I have very little understanding of his principal opponent, Bohr. (Bell 1987, 155) Niels Bohr brain-washed a generation of physicists into believing that the problem had been solved fifty years ago. (Gell-Mann 1979, 29) Every sentence I say must be understood not as an affirmation, but as a question. (Niels Bohr, quoted in Jammer 1966, 175) Bohr's interpretation has never been fully clarified. It needs an interpretation itself, and only that will be its defense. (Weizsäcker 1971, 25). (shrink)

Niels Bohr was a central figure in quantum physics, well known for his work on atomic structure and his contributions to the Copenhagen interpretation of quantum mechanics. In this book, philosopher of science Slobodan Perović explores the way Bohr practiced and understood physics, and analyzes its implications for our understanding of modern science. Perović develops a novel approach to Bohr’s understanding of physics and his method of inquiry, presenting an exploratory symbiosis of historical and philosophical analysis that uncovers the (...) key aspects of Bohr’s philosophical vision of physics within a given historical context. -/- To better understand the methods that produced Bohr’s breakthrough results in quantum phenomena, Perović clarifies the nature of Bohr’s engagement with the experimental side of physics and lays out the basic distinctions and concepts that characterize his approach. Rich and insightful, Perović’s take on the early history of quantum mechanics and its methodological ramifications sheds vital new light on one of the key figures of modern physics. (shrink)

Niels Bohr, founding father of modern atomic physics and quantum theory, was as original a philosopher as he was a physicist. This study explores several dimensions of Bohr's vision: the formulation of quantum theory and the problems associated with its interpretation, the notions of complementarity and correspondence, the debates with Einstein about objectivity and realism, and his sense of the infinite harmony of nature. Honner focuses on Bohr's epistemological lesson, the conviction that all our description of nature is dependent (...) on the words we use and the ways we can unambiguously use them. (shrink)

In this paper, the main outlines of the discussions between Niels Bohr with Albert Einstein, Werner Heisenberg, and Erwin Schrödinger during 1920–1927 are treated. From the formulation of quantum mechanics in 1925–1926 and wave mechanics in 1926, there emerged Born's statistical interpretation of the wave function in summer 1926, and on the basis of the quantum mechanical transformation theory—formulated in fall 1926 by Dirac, London, and Jordan—Heisenberg formulated the uncertainty principle in early 1927. At the Volta Conference in Como (...) in September 1927 and at the fifth Solvay Conference in Brussels the following month, Bohr publicly enunciated his complementarity principle, which had been developing in his mind for several years. The Bohr-Einstein discussions about the consistency and completeness of qnautum mechanics and of physical theory as such—formally begun in October 1927 at the fifth Solvay Conference and carried on at the sixth Solvay Conference in October 1930—were continued during the next decades. All these aspects are briefly summarized. (shrink)

Brief discussion of Niels Bohr's place in the history of philosophy (including his philosophical forebears, Søren Kierkegaard, Rasmus Nielsen, and Harald Høffding).

This is a book review of John Heilbron's book _Niels Bohr: a very short introduction_.

Abstract.Some authors have described Niels Rohr as “never being open to anything transcendental.” Wolfgang Pauli, on the other hand, spent many years trying to persuade Bohr to admit to a kind of’ mysticism. This study offers support to Pauli's claims. First, a distinction between what is vague on the one hand, and what is necessarily circular on the other, clarifies the work of Bohr. This discussion leads to comments on Bohr's attitude towards the mutuality of spirit and matter and (...) of reason and mysticism. Finally, some reflections are made about the relevance of Bohr's covert transcendental philosophy for theological endeavors. (shrink)

Com base na produção bibliográfica de Niels Bohr, entre os anos de 1913 e 1931, o presente artigo busca reconstruir o processo de elaboração das duas principais ideias do físico dinamarquês: os princípios de correspondência e complementaridade. Através desta reconstrução, busca-se analisar as possíveis motivações (a nível físico, filosófico e em prol de uma agenda de pesquisa) que guiaram Bohr neste período de elaboração da correspondência e complementaridade. Ao analisar este processo, é possível identificar que ambos os princípios estão (...) interligados, de maneira que, para a compreensão mais ampla do pensamento bohriano, é preciso considerar ambos os conceitos enquanto agentes praticamente indissociáveis. Outro aspecto discutido é quais lições epistemológicas e ontológicas Bohr nos apresenta, ao propor a correspondência e complementaridade. (shrink)

Soviet attitude towards Bohr reflects changes in the ideological approach to science. During the last period before Stalin's death danov proclaimed the campaign against Western influence in Soviet philosophy and science. Nevertheless the physicist M. A. Markov tried to introduce complementarity as a materialistic interpretation of quantum-mechanics in 1948. He was officially condemned. This was followed by a period (1948-54) during which heavy attacks were made against the Copenhagen school. In 1958, after a personal exchange of thoughts with Bohr, academician (...) Fock declared complementarity and probability to be irreversible steps towards a new insight into physical reality, at the same time correcting some of Bohr's epistemological conceptions. (shrink)

Logical positivism had an important impact on the Danish intellectual climate before World War Two. During the thirties close relations were established between members of the Vienna Circle and philosophers and scientists in Copenhagen. This influence not only affected Danish philosophy and science; it also impinged on the cultural avant-garde and via them on the public debate concerning social and political reforms. Hand in hand with the positivistic ideas you find functionalism emerging as a new heretical language in art, architecture, (...) and design. Not surprisingly, you may say, since the logical positivists’ wishes of stripping philosophy of metaphysics is spiritually similar to the functionalists’ desire to get rid of symbols and ornaments. One event more than anything confirmed the connection between the Vienna Circle, Denmark, and the rest of the Nordic countries. For a short while Copenhagen became the centre for the Circle’s activities when in 1936 the 2nd Inter national Congress for the Unity of Science was held there between June 21 and 26. A photograph, taken during the conference, shows many of the participants sitting in the hall of Carlsberg’s honorary mansion where Niels Bohr was living at the time. Among the audience you find Otto Neurath , Carl Gustav Hempel and Karl Popper , but also some of the more prominent Danish scientists and scholars whose world views were congenial with the logical positivists. (shrink)

The impact of Niels Bohr’s 1932 “Light and Life” lecture on Max Delbrück’s lifelong search for a form of “complementarity” in biology is well documented and much discussed, but the precise nature of that influence remains subject to misunderstanding. The standard reading, which sees Delbrück’s transition from physics into biology as inspired by the hope that investigation of biological phenomena might lead to a breakthrough discovery of new laws of physics, is colored much more by Erwin Schrödinger’s What Is (...) Life? than is often acknowledged. Bohr’s view was that teleological and mechanistic descriptions are mutually exclusive yet jointly necessary for an exhaustive understanding of life. Although Delbrück’s approach was empirical and less self‐consciously philosophical, he shared Bohr’s hope that scientific investigation would vindicate the view that at least some aspects of life are not reducible to physico‐chemical terms. (shrink)

The Copenhagen interpretation, which informs the textbook presentation of quantum mechanics, depends fundamentally on the notion of ontological wave-particle duality and a viewpoint called “complementarity”. In this paper, Bohr’s own interpretation is traced in detail and is shown to be fundamentally different from and even opposed to the Copenhagen interpretation in virtually all its particulars. In particular, Bohr’s interpretation avoids the ad hoc postulate of wave function ‘collapse’ that is central to the Copenhagen interpretation. The strengths and weakness of both (...) interpretations are summarized. (shrink)

Although it is, often considered a form of anti-realism, here it is argued that Bohr's complementarity viewpoint must accept entity realism based on its analysis of the causal interaction involved in observation. However, because Bohr accepts the quantum postulate he must reject the view that the goal of theory is to represent the independently existing object apart from observation. Thus he abandons the spectator account of knowledge and with it the correspondence theory of truth. In this respect his view is (...) parallel to the positions held by Hacking, Cartwright, and Ellis. (shrink)

The so-called “orthodox” interpretation of quantum physics attributed to Niels Bohr is commonly regarded as abandoning realism. I have already opposed this view elsewhere (Folse 1985) but partially in response to criticism of my position (Shimony 1985), here I propose to relate Bohr’s realism to recent contributions to the realism debate given by Hacking (1983), Cartwright (1983), and Ellis (1985). Specifically, I argue that Bohr’s complementarity viewpoint requires a causal entity realism. Furthermore, labeling Bohr an anti-realist with respect to (...) theories is misleading because it assumes the correspondence theory of truth that Bohr holds quantum theory forces us to reject.Although there are many realist views, I take the root of realism to be the quest for knowledge about the reality producing the phenomena we experience. It is realism in this sense that Bohr defended and that makes science significant to metaphysics. (shrink)

In the present paper I aim to discuss the philosophical foundations of the early correspondence principle, by comparing the conceptual structure underlying the first correspondence principle with the procedure of analogy that Immanuel Kant introduced in the Critique of Judgment from 1790. On such a comparison, I will seek to demonstrate the consistency of the conceptual ratio according to which the correspondence principle is to the classical "concepts" of space and time, as these a priori forms of intuition, in Kant, (...) are related to the separate faculty of pure intuition. As a result, it will turn out that the conceptual structure of the correspondence principle suits to the Kantian doctrine of a separate faculty of pure intuition, which is divided from the faculty of understanding. The aim is to shed new light on the line of reasoning underlying Niels Bohr's analogical thinking in quantum physics. (shrink)

Soviet attitude towards Bohr reflects changes in the ideological approach to science. During the last period before Stalin's death ?danov proclaimed the campaign against Western influence in Soviet philosophy and science. Nevertheless the physicist M. A. Markov tried to introduce complementarity as a materialistic interpretation of quantum?mechanics in 1948. He was officially condemned. This was followed by a period (1948?54) during which heavy attacks were made against the Copenhagen school. In 1958, after a personal exchange of thoughts with Bohr, academician (...) Fock declared complementarity and probability to be irreversible steps towards a new insight into physical reality, at the same time correcting some of Bohr's epistemological conceptions. (shrink)

Der gute Mensch von Kopenhagen - Niels Bohr und die Entfesselung des Atoms Der Physiker und Nobelpreisträger Niels Bohr (1885?1962) veränderte durch seine Forschung unseren Blick auf die Welt. Mit seinem Atommodell konnte erstmals die Stabilität von Materie erklärt werden, doch zugleich machten die darauf aufbauende Atomphysik und Nukleartechnik unsere Welt so unsicher wie nie zuvor. Ernst Peter Fischer beleuchtet Leben und Werk dieses faszinierenden Mannes, dessen Erkenntnisse uns bis heute beschäftigen. Ernst Peter Fischer, geboren 1947 in Wuppertal, (...) studierte Mathematik, Physik und Biologie und promovierte 1977 am California Institute of Technology. 1987 habilitierte er sich im Fach Wissenschaftsgeschichte und lehrt seither an der Universität Konstanz. Als Wissenschaftspublizist schreibt er für GEO, Bild der Wissenschaft, Die Weltwoche und die Frankfurter Allgemeine Zeitung. Fischer ist Autor zahlreicher Bücher, darunter der Bestseller?Die andere Bildung?(2001) und die Max-Planck-Biographie?Der Physiker?(2007). Für seine Arbeit erhielt er mehre Preise, u. a. den Sartorius-Preis der Akademie der Wissenschaften zu Göttingen. (shrink)

A review of *Niels Bohr’s Philosophy of Quantum Physics in the Light of the Helmholtzian Tradition of Theoretical Physics *.