The analogical extensions of Niels Bohr's principle of complementarity to the disciplines of biology, psychology, and theology are ineffective. It has been argued, moreover, that the principle of complementarity is ineffective within quantum theory itself. Bohr supported the claim that complementary pictorial-level interpretations are necessary for the explanation of quantum phenomena by invoking a correspondence argument. Henry Margenau criticized Bohr for recommending that physicists accept an irreconcilable dilemma, the horns of which are complementary "descriptions" in terms of classical observables and causal accounts in terms of abstract states. In his various publications, Margenau created a number of diagrams to represent the confirmation process. He agreed with P. W. Bridgman that operational definitions provide important links between constructs and the results of instrumental procedures. Despite Margenau's protest, many scientists in the 1930s were receptive to the idea that pictures of classical particles and waves are needed to complete the interpretation of quantum phenomena.
The analogical extensions of Niels Bohr's principle of complementarity to the disciplines of biology, psychology, and theology are ineffective. It has been argued, moreover, that the principle of complementarity is ineffective within quantum theory itself. Bohr supported the claim that complementary pictorial-level interpretations are necessary for the explanation of quantum phenomena by invoking a correspondence argument. Henry Margenau criticized Bohr for recommending that physicists accept an irreconcilable dilemma, the horns of which are complementary "descriptions" in terms of classical observables and causal accounts in terms of abstract states. In his various publications, Margenau created a number of diagrams to represent the confirmation process. He agreed with P. W. Bridgman that operational definitions provide important links between constructs and the results of instrumental procedures. Despite Margenau's protest, many scientists in the 1930s were receptive to the idea that pictures of classical particles and waves are needed to complete the interpretation of quantum phenomena.
Niels Bohr accepted the distinction stressed by Immanuel Kant and others between the awareness of an object and the awareness of being aware of that object. He noted that one of the "epistemological implications" of the success of quantum theory is the necessity of directing attention to the "placing of the subject-object distinction". Causal pictures and vitalistic pictures, like particle pictures and wave pictures in quantum theory, are interpretations that supplement each other. These pictures are complementary in the sense that both types of picture are required for completeness. This is the case both in quantum physics and psychology. The mutual exclusivity of interpretations is a cornerstone of the principle of complementarity, as it is applied within quantum theory. Bohr's analogical extension of the principle of complementarity to psychology is unconvincing. A more appropriate analogy to causal and vitalistic interpretations in psychology would be from fluid and particulate models of the behavior of aqueous solutions.
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.
This article explores Bohr's argument, advanced under the heading of 'complementarity,' concerning quantum phenomena and quantum mechanics, and its physical and philosophical implications.In Bohr, the term complementarity designates both a particular concept and an overall interpretation of quantum phenomena and quantum mechanics, in part grounded in this concept.While the argument of this article is primarily philosophical, it will also address, historically, the development and transformations of Bohr's thinking, under the impact of the development of quantum theory and Bohr's confrontation with Einstein, especially their exchange concerning the EPR experiment, proposed by Einstein, Podolsky and Rosen in 1935.Bohr's interpretation was progressively characterized by a more radical epistemology, in its ultimate form, which was developed in the 1930s and with which I shall be especially concerned here, defined by his new concepts of phenomenon and atomicity.According to this epistemology, quantum objects are seen as indescribable and possibly even as inconceivable, and as manifesting their existence only in the effects of their interactions with measuring instruments upon those instruments, effects that define phenomena in Bohr's sense.The absence of causality is an automatic consequence of this epistemology.I shall also consider how probability and statistics work under these epistemological conditions.
‘The new wave mechanics gave rise to the hope that an account of atomic phenomena might be obtained which would not differ essentially from that afforded by the classical theories of electricity and magnetism. Unfortunately, Bohr's statement in the following communication of the principles underlying the description of atomic phenomena gives little, if any, encouragement in this direction.’ This comment is to be found in the brief note prefaced by the editors of the British journal Nature to Niels Bohr's paper ‘The Quantum Postulate and the Recent Development of Atomic Theory’ in the supplement of 14 April 1928. The article in question is the famous paper which first introduced and defined the concept of ‘complementarity’ and outlined the basic points of what was to become known as the Copenhagen interpretation of quantum mechanics. In the paper, Bohr returned to the arguments contained in the paper discussed at the International Congress of Physicists held at Como in September 1927 to mark the centenary of the death of Alessandro Volta and published in the proceedings of the same congress. It was probably his conviction that the new viewpoint adopted in the description of nature fully expressed the theoretical and cognitive content of quantum physics coupled with his enthusiasm at having achieved ‘after many years of struggling in the dark […] the fulfilment of the old hopes’ that induced him to give his work broader and more prestigious circulation.
The views of Niels Bohr on complementarity are examined, both in physics and in other fields. N. Bohr's opinions on the relationship between physics and biology are discussed in detail. It is shown that, over a number of years, Bohr viewed as complementary the study of organisms as atomic-molecular and as integral systems. Subsequently, owing to the development of molecular biology, Bohr rejected the idea of the complementarity in principle of the stated two types of studies. The current status of the physical theory of biological phenomena is examined, and the role of synergetics in this field is noted. The so-called antireductionism is criticized. It is shown that the views of contemporary eminent theoretical biologists reveal them to be unfamiliar with physics. The very important role of physics in the further development of biology and its practical applications is emphasized.
In this study Arun Bala examines the implications that Niels Bohr’s principle of complementarity holds for fields beyond physics. Bohr, one of the founding figures of modern quantum physics, argued that the principle of complementarity he proposed for understanding atomic processes has parallels in psychology, biology, and social science, as well as in Buddhist and Taoist thought. But Bohr failed to offer any explanation for why complementarity might extend beyond physics, and his claims have been widely rejected by scientists as empty speculation. Scientific scepticism has only been reinforced by the naïve enthusiasm of postmodern relativists and New Age intuitionists, who seize upon Bohr’s ideas to justify anti-realist and mystical positions. Arun Bala offers a detailed defence of Bohr’s claim that complementarity has far-reaching implications for the biological and social sciences, as well as for comparative philosophies of science, by explaining Bohr’s parallels as responses to the omnipresence of grown properties in nature.