Bohr’s reply to Einstein, Podolsky, and Rosen’s argument for the incompleteness of quantum theory is notoriously difficult to unravel. It is so diffcult, in fact, that over 60 years later, there remains important work to be done understanding it. Work by Fine , Beller and Fine , and Beller goes a long way towards correcting earlier misunderstandings of Bohr’s reply. This essay is intended as a contribution to the program of getting to the truth of the matter, both historically and (...) philosophically. In a paper of this length, a full account of Bohr’s reply is impossible, and so I shall focus on one issue where it seems further clarification is required, namely, Bohr’s attempt to illustrate EPR’s argument by means of a thought experiment. In addition, I shall attempt to clarify a few other points which, however minor, have apparently contributed to misunderstandings of Bohr’s position. As the title of this paper suggests, an account of these few points does not constitute an account of Bohr’s reply, but it is an important step in that direction. (shrink)

In contrast to the theories of relativity, quantum mechanics is not yet based on a generally accepted conceptual foundation. It is proposed here that the missing principle may be identified through the observation that all knowledge in physics has to be expressed in propositions and that therefore the most elementary system represents the truth value of one proposition, i.e., it carries just one bit of information. Therefore an elementary system can only give a definite result in one specific measurement. The (...) irreducible randomness in other measurements is then a necessary consequence. For composite systems entanglement results if all possible information is exhausted in specifying joint properties of the constituents. (shrink)

Properties sometimes attributed to the “particle” aspect of a neutron, e.g., mass and magnetic moment, cannot straightforwardly be regarded in the Bohm interpretation of quantum mechanics as localized at the hypothetical position of the particle. This is shown by examining a series of effects in neutron interferometry. A related thought-experiment also provides a variation of a recent demonstration that which-way detectors can appear to behave anomolously in the Bohm theory.

"Science is rooted in conversations," wrote Werner Heisenberg, one of the twentieth century's great physicists. In Quantum Dialogue, Mara Beller shows that science is rooted not just in conversation but in disagreement, doubt, and uncertainty. She argues that it is precisely this culture of dialogue and controversy within the scientific community that fuels creativity. Beller draws her argument from her radical new reading of the history of the quantum revolution, especially the development of the Copenhagen interpretation. One of several competing (...) approaches, this version succeeded largely due to the rhetorical skills of Niels Bohr and his colleagues. Using extensive archival research, Beller shows how Bohr and others marketed their views, misrepresenting and dismissing their opponents as "unreasonable" and championing their own not always coherent or well-supported position as "inevitable." Quantum Dialogue, winner of the 1999 Morris D. Forkosch Prize of the Journal of the History of Ideas, will fascinate everyone interested in how stories of "scientific revolutions" are constructed and "scientific consensus" achieved. "[A]n intellectually stimulating piece of work, energised by a distinct point of view."—Dipankar Home, Times Higher Education Supplement "[R]emarkable and original. . . . [Beller's] arguments are thoroughly supported and her conclusions are meticulously argued. . . . This is an important book that all who are interested in the emergence of quantum mechanics will want to read."—William Evenson, History of Physics Newsletter. (shrink)

Why does one theory "succeed" while another, possibly clearer interpretation, fails? By exploring two observationally equivalent yet conceptually incompatible views of quantum mechanics, James T. Cushing shows how historical contingency can be crucial to determining a theory's construction and its position among competing views. Since the late 1920s, the theory formulated by Niels Bohr and his colleagues at Copenhagen has been the dominant interpretation of quantum mechanics. Yet an alternative interpretation, rooted in the work of Louis de Broglie in the (...) early 1920s and reformulated and extended by David Bohm in the 1950s, equally well explains the observational data. Through a detailed historical and sociological study of the physicists who developed different theories of quantum mechanics, the debates within and between opposing camps, and the receptions given to each theory, Cushing shows that despite the preeminence of the Copenhagen view, the Bohm interpretation cannot be ignored. Cushing contends that the Copenhagen interpretation became widely accepted not because it is a better explanation of subatomic phenomena than is Bohm's, but because it happened to appear first. Focusing on the philosophical, social, and cultural forces that shaped one of the most important developments in modern physics, this provocative book examines the role that timing can play in the establishment of theory and explanation. (shrink)

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 quantum theory of de Broglie and Bohm solves the measurement problem, but the hypothetical corpuscles play no role in the argument. The solution finds a more natural home in the Everett interpretation.

— Niels Bohr, 19231 “There must be quite definite and clear grounds, why you repeatedly declare that one must interpret observations classically, which lie absolute ly in thei r essenc e. . . . It must belong to your deepest conviction—and I cannot understand on what you base it.”.