Quantum Drummer

Introduction

       In the time period between 1913 and 1930, Niels Bohr and his team of scientists at the Copenhagen Institute developed the theories of Quantum Physics, one of the most complete and complicated set of knowledge regarding the way the Universe behaves. This work is known as the Copenhagen interpretation of Quantum Theory. In order to develop the quantum theories, they were required to break the dogma and paradigms of classical physics, and enter in a strong debate with Einstein and other leader scientists of the time. Bohr’s atomic theory from 1913 and his views on complementarity from 1927 conform a radical separation from the previous Newtonian paradigm. For this reason, great interest has been placed in trying to understand how Bohr was able to develop these ideas and think what others were not able to think. Historians of science have tried to look for Bohr’s sources of inspiration, even outside of the domain of pure science, and the most accepted belief is that Bohr was able to achieve this task because he had a special philosophical background, very different from his contemporary peers (Favrholdt, 1992, p. 6).

      There is some evidence that seems to point out that Bohr received influence from the works of William James, particularly in regards to the development of complementarity. Holton (1973) indicates that among German scientists Bohr used to mention James but only a few other philosophers, and his 1929 work The Quantum of Action and Description of Nature “could well refer directly to William James’ chapter on the ‘Stream of Thought’ in James’ book, The Principle of Psychology (1890).” (Holton, 1973, p. 122). The physicist Leon Rosenfeld, close colleague of Bohr’s, points out that Bohr became interested and excited about James’ work until around 1932, many years after the completion of Bohr’s theories. Rosenfeld also says that Bohr himself told him one time that “you must not forget that I was quite alone in working out these ideas, and had no help from anybody.” (Holton, 1973, p. 122).

       On an interview with Bohr, held on November 17, 1962 by T.S. Kuhn, A. Petersen and E. Rudinger one day before Bohr’s death, Kuhn asked Bohr whether he actually read some of the works of various philosophers. Bohr recollects that with intervention of his friend Rubin, who was a psychologist, he read the work of William James, and specifically mentions The Steam of Thought. From this interview, the exact time when Bohr read James’ work is not clear, and this interview only adds to the debate between the believers of James’ influence on Bohr and the believers of Bohr’s independent work. (Holton, 1970, p. 1035).

      Regardless if James was an influence to Bohr and his team or not, Stapp (2007) shows that by reading James’ work, we can clearly see how he foresaw the fall of classical physics, which does not allow for any involvement of the mind on its precepts, while the connections described in James’ works provide an explanation that supports the belief that the same dynamical principles that explain atomic phenomena are shown in the mind-brain dynamics, when the world is seen not as made of matter, but rather “as an informational structure that causally links the two elements that combine to constitute actual scientific practice, namely the psychologically described contents of our streams of conscious experiences and the mathematically described objective tendencies that tie our chosen actions to experience.” (Stapp, 2007, p. 38).

The Concept of Correspondence

        One of the areas where there is great similarity in the works of Bohr with the earlier philosophy of James is in the concept of correspondence, when applied to “transitive parts” or “leaps”. Holton (1970) describes how, during Kuhn’s interview with Bohr, he mentions that after reading the chapter “The Stream of Thought” from James’ book The Principles of Psychology (1890), one can find that James establishes that thoughts can exist only in relation to the specific owner of that thought, making the thought and the thinker, subject and object, tightly coupled (Holton, 1970, p. 1036).  If we read the works of James, we found how he describes that “Consciousness does not appear to itself chopped up in bits……It is nothing jointed; it flows. A ‘river’ or a ‘stream’ are the metaphors by which it is most naturally described. In talking of it thereafter, let us call it the stream of thought, of consciousness, or of subjective life.” (James, 1890, p. 239).

       Furthermore, Holton (1970) describes the following metaphor presented by James: “Like a bird’s life, (thought) seems to be made of an alternation of flights and perchings. The rhythm of language expresses this, where every thought is expressed in a sentence and every sentence closed by a period…..Let us call the resting places the ‘substantive parts’ and the places of flight the ‘transitive parts’, of the stream of thought.” (Holton, 1970, p. 1036).

      Since his early work on the atomic theory, Bohr (1935) became aware that was not possible to carry out a “coherent causal description of atomic phenomena.” (p.7). The theory that he and his team were developing was not explainable by the use of classical, or causal terms. Bohr was required to introduce to his theory Heisenberg’s element of uncertainty, in which any measurement aimed to trace the motion of elementary particles brings an interference determined by the magnitude of the quantum of action, which applies to the “agencies of observation as well as to the phenomena under investigation….. The finite magnitude of the quantum of action prevents altogether a sharp distinction being made between a phenomenon and the agency by which it is observed.” (Bohr, 1935, p. 11).

      Later on, around 1929, Bohr (1935) writes about the general conditions that are present during the creation of man’s concepts (p. 15), again as an explanation of the need to leave the causal modes of classical physics. He writes: “The impossibility of distinguishing in our customary way between physical phenomena and their observation places us, indeed, in a position quite similar to that which is so familiar in psychology where we are continually reminded of the difficulty of distinguishing between subject and object.” (Bohr, 1935, p. 15). In these two parts of Bohr’s work we can see the similarities with the concepts used by James as part of his description of the relationship between thought and thinker, and the relationship of the observer and the observed.

      In addition, Bohr’s first postulate of quantum theory indicates: “An atomic system possesses a certain manifold of states, the ‘stationary states’, to which corresponds in general a discrete sequence of energy values and which have a peculiar stability. This latter shows itself in that every change in the energy of the atom must be due to a ‘transition’ of the atom from one stationary state to another.” (Bohr, 1935, p. 31). We can see here, how the concepts of stationary and transitional states by Bohr used in his atomic theory show great similarity with the concepts introduced by James in his theories of thought.

The Concept of Complementarity

       In the chapter “The relations of minds to other things”, found in James’ book The Principles of Psychology (1890), he describes how it was shown by Janet and Binet that in times of anesthesia, “and coexisting with it, sensibility to the anesthetic parts is also there, in the form of a secondary consciousness entirely cut off from the primary or normal one, but susceptible of being tapped and made to testify to its existence in various odd ways.” (James, 1890, p. 203). Later in the same chapter, James describes that in some individuals their consciousness might be split into “parts that coexist but mutually ignore each other, and share the objects of knowledge between them. More remarkable still, they are complementary.” (James, 1890, p. 206).

       In September 1927 in Como, Italy, during the International Congress of Physics, Niels Bohr for the first time introduced to the public his formulation of complementarity (Holton, 1973, p.99). In tackling the behavior of particles at the quantum level, Bohr was required to move away, once again, from classical physics by using a different philosophical basis. The problem was in regards to how to explain the behavior of some fundamental properties of matter at the elementary particle level, such as momentum and position, in a way that Heisenberg’s Uncertainty Principle is maintained. Classical theories indicate that the behavior of particles can be completely described in terms of “suitable dynamical variables which are all, in principle, capable of being defined at the same time with arbitrarily high precision” (Bohm, 1951, p. 158) but according to the uncertainty principle, momentum and position cannot be known at the same time, and should be considered “interwoven variables” or more accurately, “interwoven potentialities” representing opposing properties that can be comparatively well defined under different conditions. Per Bohm (1951), these potentialities complement each other, since each is necessary in a complete description of the physical processes through which the electron manifests itself; hence the name ‘principle of complementarity.’ “ (p. 159).

       As shown in the presented evidence, similar to the concept of split consciousness in some individuals during anesthesia, described as being “complementary” by James in his work published in 1890, Bohr  later provides in his works  a description of momentum and position properties in elementary particles as “complementary” to each other, raising the possibility that it was James’ philosophy that influenced Bohr in the development of his quantum theories.

General Concepts in Pragmatism  

      One of the elements of the philosophy of Pragmatism that seems to be found in Bohr’s philosophy is the Principle of Peirce, which estates that “To attain perfect clearness in our thoughts of an object, then, we need only consider what conceivable effects of a practical kind the object may involve – what sensations we are to expect from it, and what reactions we must prepare.” (James, 1907, p. 20).  Another important element is the concept of unity, including the elements of continuity, causal unity, generic unity and unity of purpose. In this regard, James (1907) summarizes that “The oneness of things, superior to their manyness, you think must also be more deeply true, must be the more real aspect of the world. The pragmatic view, you are sure, gives us a universe imperfectly rational. The real universe must form an unconditional unit of being, something consolidated, with its parts co-implicated through and through.” (p. 65).

      Bohr orientation seems to be strongly pragmatic. Plotnitsky (1994) cites Murdoch in describing how “Bohr was agreeing that whether or not electrons have such conjunctive property (simultaneously existing position and momentum) (even though we cannot measure it) is a metaphysical question in the pejorative sense which positivists are wont to give this term…..The basis of Bohr’s agreement however, was not positivism, but pragmatism.” (Plotnitsky, 1994, p. 84). Also, Beller (1999) writes that Bohr’s concept of wholeness goes back to James’ analysis of mental phenomena, in which Bohr connects to the idea of wholeness expressed by James: “If you have some things…. They are so connected that if you try to separate them from each other, it just has nothing to do with the actual situation.” (Beller, 1999, p. 255). Stapp (1972) writes that Bohr believed that there is an element of wholeness in the atomic process, which is related to the quantum of action, and completely unknown to classical science, which rejects the classical beliefs of having the measuring instruments and the atomic objects as separate from each other, and that “the resulting inseparability of the atomic object from the whole phenomenon renders statistical description unavoidable.” (Stapp, 1972, p. 1109).

      Stapp (1972) also makes a strong point regarding the pragmatic orientation of the Copenhagen interpretation (p. 1105), referencing the opening words of Bohr’s first book: “The task of science is both to extend the range of our experience and reduce it to order….In physics our problem consists in the co-ordination of our experience of the external world…. In our description of nature the purpose is not to disclose the real essence of phenomena but only to track down as far as possible relations between the multifold aspects of our experience.” (Bohr, 1934, p. 1). Boh’r pragmatism is demonstrated in the way that he developed his theories with a focus in what worked and made sense first, having a strong basis on the experience itself, and then in searching for the detailed theoretical and mathematical explanation.

The connection: James-Bohr

      Exactly how did Bohr was made aware of James’ theories and philosophies is not known. There are several possible explanations that historians have identified, based on the known fact that Bohr read the chapter “The Steam of Thought” from James’ book The Principles of Psychology, and he was very enthusiastic about it (Favrholdt, 1992, p. 64). The issue is to identify exactly when did Bohr read James’ works, so it can be determined if his theories developed in the early years of the Copenhagen Institute, between 1913 and 1927, could already have been influenced by James’ philosophies. There is no evidence of direct contact between Bohr and James, but it is possible that Bohr’ read James’ works as early as 1905. The way this possible connection is explained occurs through Bohr’s teacher and friend Harald Hoffding, who attended a conference in St. Louis in 1904, and later visited James at his home in New Hampshire. Bohr, his friend Rubin, a psychologist, and Hoffding, all frequently attended talks at a group called the Ekliptika-circle, and it is very possible that Hoffding brought up the works of James in these conversations, raising Bohr’s awareness and interest. (Favrholdt, 1992, p. 64). However, Leon Rosenfeld, who collaborated with Bohr later, strongly suggests that Bohr did not read James until 1935 or 1936 even if he might have heard about him in 1905 (Favrholdt, 1992, p. 67).

       Holton (1973) describes two possible sides of the story, either Bohr read James early enough to be directly influenced by his ideas, or as Rosenfeld claims, Bohr independently arrived to similar thoughts and conclusions, and only later became enthusiastic about James works (p. 123). There are defenders on both sides of the debate, such as Meyer-Abich (2004), who shows how Bohr studied and appreciated James’ works as part of the development of the complementarity concept (p. 95), and how Bohr’s philosophy of knowledge “may be denoted as pragmatic in the Greek sense. As William James, one of the founding fathers of modern pragmatism, put it: ‘Man engenders truth upon’ the world.” (Meyer-Abich, 2004, p. 96). On the other hand, we find some extreme explanations, as in the case of Favrholdt (1992) who indicates that “Bohr was a completely independent thinker; from early youth, he developed his epistemological ideas single-handed and with no more philosophical preparation than Hoffding’s elementary course of lectures.” (p. 40). This seems to be an aggressive attempt on defending Bohr’s capabilities but does not have any real and sustainable basis.

      Another potential lead in finding the connection of Bohr with James could be the search for young physicists that could have been in contact with James between 1890 and 1907, and that later participated with Bohr in Copenhagen. That could indirectly the case of J.C. Slater, an American physicist that worked with Bohr in Copenhagen and co-authored the famous paper known as “the BKS paper” in 1924. (Beller, 1999, p. 23). Slater did graduate studies in Physics at Harvard, and was assistant to Professor Percy Williams Bridgman (Kuhn, T. & Van Vleck, J., 1963, p. 12). Bridgman arrived to study physics at Harvard in 1900 and later became a distinguished physicist known for his interest in philosophy and pragmatism (Kremble & Birch, 1970, p. 24). Exactly how much, if any, contact did Bridgman had with James and how much of the philosophy could have been transferred to Slater and eventually to Bohr is unknown, but it might be worth analyzing as a potential source of connection between James and Bohr.

Conclusion

       With the development of the quantum theory, more than any other pioneers, Niels Bohr participated in the development of a general philosophical point of view that broke old paradigms of the classical science and provided a brand new understanding of physical reality. Bohr ‘s essays and lectures led up to the explanation of the concepts such as complementarity through an historical survey of the development of quantum physics, using a “rational reconstruction” of the stories, selecting the events with the philosophical objective of making the complementarity viewpoint appear as inevitable and best possible answer (Faye, J. & Folse, H., 1998, p. 2). The rational reconstruction of this development of scientific knowledge deserves a detailed analysis in the attempt to understand the genesis of ideas, and in the case of Bohr and his ideas on complementarity and correspondence, there seems to be wide evidence of the influence of William James. 

Beller (1999) indicates, quoting Werner Heisenberg, that “Science is rooted in conversations.” (p. 1) So a good question to analyze is how much of an extended and indirect conversation occurred between William James and Niels Bohr in the development of quantum physics. This paper has presented some evidence of that conversation, but there is much more analysis required to be able to reach a solid conclusion.

References

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Faye, J. & Folse, H. (ed) (1998) The Philosophical Writings of Niels Bohr, Volume IV: Causality and Complementarity. Woodbridge, CT: Ox Bow Press.

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Holton, G. (1973). Thematic Origins of Scientific Thought: Kepler to Einstein. Cambridge, MA: Harvard University Press.

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Kremble, E. & Birch, F. (1970). Percy Williams Bridgman 1882-1961, A Biographical Memoir. Washington DC: National Academy of Sciences.

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Meyer, Abich, K. (2004) Bohr’s Complementarity and Goldstein’s Holism in Reflective Pragmatism Mind and Matter 2 (2) p. 91-103.

Plotnitsky, A. (1994). Complementarity. Durham, NC: Duke University Press.

Stapp, H. P. (1972) The Copenhagen Interpretation, AJP Vol. 40 p. 1098-1116.

Stapp, H. P. (2007) Mindful Universe: Quantum Mechanics and the Participating Observer. New York, NY: Springer.