Contrary to Mermin, Bohr Did Acknowledge a Significant Quantum Measurement Problem - The Importance of William James, The Early American Psychologist, To Bohr, Mermin, And Carroll’s Epistemic Option For Quantum Measurement
James’s complementarity works very well with the proofs that are at the heart of null and positive measurements in quantum mechanics. It is important for the physics community to know that complementarity originated in psychology in 1890, in the work of William James, to know James’s finding that “the total possible consciousnesses may be split into parts which coexist but mutually ignore each other, and share the objects of knowledge between them.” The human observer is central in James’s formulation of complementarity. Consciousness and knowledge are essential. It appears that James’s concept of complementarity may truly characterize what Carroll is referring to as the epistemic option. It seems it is likely the correct conceptual model for quantum mechanical measurement. For example, there can be no hidden physical variables with a null measurement because the outcome of a null measurement as discussed above is not dependent on a physical interaction. Bohr was open to ideas from psychology. Bohr borrowed James’s complementarity and adapted it for physics by introducing an unavoidable physical interaction between a physical measuring instrument and the physical system measured. This physical interaction has an aspect that cannot be controlled. This lack of control allowed Bohr to apply the uncertainty principle. Bohr’s complementarity for physics is unwarranted. Once there is a logical proof that the electron will not pass through one of the slits, the wave component associated with the slit through which the electron does not pass vanishes. No superposition is possible because that wave component has vanished. Contrary to Mermin, Bohr did acknowledge a significant quantum measurement problem. Bohr held to his view discussed above of complementarity for physics instead of adopting James’s approach where the knowing individual is directly related to the physical system measured as an object of knowledge. Perhaps through the collaboration of physics and other fields, in particular psychology, further progress can be made in developing a self-consistent view of quantum mechanical measurement that is supported by empirical evidence.
James’s complementarity works very well with the proofs that are at the heart of null and positive measurements in quantum mechanics. It is important for the physics community to know that complementarity originated in psychology in 1890, in the work of William James, to know James’s finding that “the total possible consciousnesses may be split into parts which coexist but mutually ignore each other, and share the objects of knowledge between them.” The human observer is central in James’s formulation of complementarity. Consciousness and knowledge are essential. It appears that James’s concept of complementarity may truly characterize what Carroll is referring to as the epistemic option. It seems it is likely the correct conceptual model for quantum mechanical measurement. For example, there can be no hidden physical variables with a null measurement because the outcome of a null measurement as discussed above is not dependent on a physical interaction. Bohr was open to ideas from psychology. Bohr borrowed James’s complementarity and adapted it for physics by introducing an unavoidable physical interaction between a physical measuring instrument and the physical system measured. This physical interaction has an aspect that cannot be controlled. This lack of control allowed Bohr to apply the uncertainty principle. Bohr’s complementarity for physics is unwarranted. Once there is a logical proof that the electron will not pass through one of the slits, the wave component associated with the slit through which the electron does not pass vanishes. No superposition is possible because that wave component has vanished. Contrary to Mermin, Bohr did acknowledge a significant quantum measurement problem. Bohr held to his view discussed above of complementarity for physics instead of adopting James’s approach where the knowing individual is directly related to the physical system measured as an object of knowledge. Perhaps through the collaboration of physics and other fields, in particular psychology, further progress can be made in developing a self-consistent view of quantum mechanical measurement that is supported by empirical evidence.
Today it is important to see James’s original complementarity in 1890 independently of Bohr’s discussions on complementarity in order that James’s conception can be properly evaluated as the model on its own merits for quantum measurement. On the basis of new evidence and a deeper analysis of previous evidence presented here, it is very reasonable to conclude based on Bohr’s own words that Bohr read James’s complementarity between approximately 1908 and 1912. An Appendix provides the relevant text from both Bohr’s Nobel biography and his interview with the American Institute of Physics to support this conclusion. Bohr’s description of significant events in his life are matched with dates in his Nobel biography, adding support to the conclusion. How Bohr specifically adapted James’s complementarity to physics is presented. Bohr’s discussion of “mental activity” is compared here to James’s definition of complementarity focusing on consciousness and is found to be extremely similar to James’s definition. In addition, a side by side comparison of James’s definition of complementarity and Bohr’s most important and well-known definition of complementarity for physics is presented. This comparison shows just how Bohr adapted James’s complementarity to Bohr’s complementarity for physics. Examining the chapters “The Stream of Thought”” (chapter 9 in James’s “The Principles of Psychology”) and “The Relation of Minds to Other Things” (chapter 8 in “The Principles of Psychology”) shows that the very evidence that James used to develop complementarity in “The Relation of Minds to Other Things” is discussed in “The Stream of Thought,” a chapter that Bohr acknowledged reading and concerning which he had a very high opinion. It is also made clear in the paper that Bohr was aware that he had a choice to adopt complementarity for physics along the lines of James’s complementarity, which he had read, and that he rejected this possibility. Instead, in his complementarity for physics, Bohr adopted a very different approach fundamentally based on the necessity of a physical interaction between a physical system and a physical measuring apparatus with an uncontrolled aspect to obtain a specific measurement result. Bohr attempted to apply the uncertainty principle to this uncontrolled feature of the physical interaction. Bohr’s approach has been the widely adopted framework for understanding quantum measurement since 1927. The historical description of complementarity in Bohr’s Nobel biography is discussed in light of the evidence presented and is shown to be incorrect. It is important to set the record straight regarding the origin of complementarity so that James’s complementarity is not seen as an appendage of Bohr’s version of complementarity for physics. Bohr’s attempt to extrapolate what his Nobel biography incorrectly states was complementarity originally developed by Bohr, which was for physics, to other fields confuses and detracts from the importance of James’s complementarity which was in fact the original. Bohr’s detour with his proposed necessity (and its proposed fundamental significance) of a physical interaction in the measuring process with an uncontrolled aspect in quantum mechanics has distracted attention away from the possible significance of James’s original concept in psychology to quantum measurement, including its evaluation on its own merits as to whether it provides the correct conceptual framework for this measurement.
Having discussed the meaning of complementarity in general and wave particle complementarity in particular, I wish now to explicate Bohr's subtle argument for the thesis that certain pairs of classical concepts which are mutually compatible in classical physics are mutually exclusive in quantum physics, i.e. the thesis of kinematic–dynamic complementarity. It is generally held that Bohr regarded the mutual exclusiveness in question as being not only epistemic but also ontic or semantic, in the sense that the uncertainty principle expresses a restriction not only on the joint measurability of canonically conjugate observables but also on the joint instantiation of the properties corresponding to these observables. I shall consider the question of the ontic or semantic construal of kinematic–dynamic complementarity in Chapter 7. Bohr's argument for complementarity in the epistemic sense is, however, more fundamental: it goes to the heart of his theory of observation and measurement in quantum physics. What, then, is Bohr's argument? The mutual exclusiveness of kinematic and dynamic properties Kinematic and dynamic attributes in quantum mechanics are mutually exclusive in the sense that they cannot be simultaneously measured; they are, in this sense, epistemically incompatible. Why did Bohr think this? His reasons may seem intricate, but they are basically quite simple. Two main factors, he maintains, account for the epistemic incompatibility: ( a ) measurements of these two different sorts of properties require mutually exclusive experimental arrangements, incompatible measurement procedures; ( b ) the indeterminability of the interaction between the object and the instrument of measurement precludes extrapolation of the different measurement results to one and the same time.
The theory of complementarity became prominent during the last century (primarily as a result of the ideas of Niels Bohr and quantum physics). It gradually developed into a dominant paradigm un-derlying research into the nature of existence. Bohr’s exposition of the principle also emphasized its epistemological value for providing more accurate information regarding what seem to be paradoxical aspects of reality. The principle of complementarity has proven to have far reaching philosophical im-plications concerning such basic notions as subject and object, space-time and causality, chance and necessity, and more. However, scholars also acknowledge that it contributes to resolving the problem of the discontinuity between underlying reality and the human ability to conceptualize the ontological nature of existence. It has grown in popularity because it seems to off er a means of addressing dichoto-mies in other sciences and in philosophy.When analysts scrutinize the factors that infl uenced Bohr’s understanding of the principle of comple-mentarity they fi nd that one source clearly stems from the infl uence of American Pragmatism. Although the Pragmatist infl uence is traced primarily to William James there is at the roots of the philosophy of Pragmatism reference made to concepts that refl ect the principle of complementarity explicating how to gain reliable knowledge concerning the nature of existence. From the very inception of American Prag-matism there was the recognition that Western philosophy faced a problem connected with
Ninety years ago in 1927, at an international congress in Como, Italy, Niels Bohr gave an address which is recognized as the first instance in which the term "complementarity", as a physical concept, was spoken publicly [1], revealing Bohr's own thinking about Louis de Broglie's "duality". Bohr had very slowly accepted duality as a principle of physics: close observation of any quantum object will reveal either wave-like or particle-like behavior, one or the other of two fundamental and complementary features. Little disagreement exists today about complementarity's importance and broad applicability in quantum science. Book-length scholarly examinations even provide speculations about the relevance of complementarity in fields as different from physics as biology, psychology and social anthropology, connections which were apparently of interest to Bohr himself (see Jammer [2], Murdoch [3] and Whitaker [4]). Confusion evident in Como following his talk was not eliminated by Bohr's article [1], and complementarity has been subjected to nine decades of repeated examination ever since with no agreed resolution. Semi-popular treatments [5] as well as expert examinations [6-9] show that the topic cannot be avoided, and complementarity retains its central place in the interpretation of quantum mechanics. However, recent approaches by our group [10-13] and others [14-20] to the underlying notion of coherence now allow us to present a universal formulation of complementarity that may signal the end to the confusion. We demonstrate a new relationship that constrains the behavior of an electromagnetic field (quantum or classical) in the fundamental context of two-slit experiments. We show that entanglement is the ingredient needed to complete Bohr's formulation of complementarity, debated for decades because of its incompleteness.
Niels Bohr developed the framework of complementarity in response to the binding of measuring device and quantum system into an irreducible whole or "individual" at the instant of measurement. On the grounds that an organism and its environment are also bound irreducibly upon interaction, Bohr extended complementarity to biology and psychology, treating mechanistic reduction of the organism and neural objectification of consciousness as mere perspectives opposed by equally valid perspectives. In contrast to Bohr's aversion to metaphysical speculation, Heisenberg suggested that the quantum-mechanical wave function represents a real entity which determines probable outcomes of measurements given the forces acting on the system. In light of Bohr's parallel between quantum and biological systems, the probability wave of the atom ought to be mirrored in the equally intangible consciousness of the organism. I propose further that life is indeed an irreducible property of the organism and that mechanistic biology mischaracterizes life. Key to my analysis is the dual nature of time.