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Historical Studies in the Physical and Biological Sciences

Léon Rosenfeld's Marxist defense of complementarity

Anja Skaar Jacobsen

Published Mar 1, 2007• 24 citations

Abstract

The Belgian physicist Leeon (1904––1974) has been called clarifier of Niels Bohr's ideas in quantum mechanics. He had a unique connection to Bohr as his close collaborator from 1930 until Bohr died in 1962. However, although he is considered Bohr's spokesman, he had his own characteristic way of articulating Bohr's views. In particular, added a dialectical-materialist layer to Bohr's ideas in certain contexts. Despite Rosenfeld's open profession of Marxism, the literature has generally avoided discussing its relevance for his work and activities. This paper suggests some reasons why and investigates Rosenfeld's combination of Marxism and complementarity, which his colleague and friend Wolfgang Pauli metaphorically denoted by the equation Rosenfeld = √√Trotsky ×× Bohr. Rosenfeld's particular views appear anomalous to the frequently expressed stereotypes of both Marxism and complementarity. The paper concentrates on the role Marxist philosophy played in Rosenfeld's fierce defense of complementarity from the late 1940s through the 1950s and the reception his campaign was accorded at the Niels Bohr Institute in Copenhagen and elsewhere.

DOI: 10.1525/hsps.2007.37.s.3

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The Belgian physicist Leeon (1904––1974) has been called clarifier of Niels Bohr's ideas in quantum mechanics. He had a unique connection to Bohr as his close collaborator from 1930 until Bohr died in 1962. However, although he is considered Bohr's spokesman, he had his own characteristic way of articulating Bohr's views. In particular, added a dialectical-materialist layer to Bohr's ideas in certain contexts. Despite Rosenfeld's open profession of Marxism, the literature has generally avoided discussing its relevance for his work and activities. This paper suggests some reasons why and investigates Rosenfeld's combination of Marxism and complementarity, which his colleague and friend Wolfgang Pauli metaphorically denoted by the equation Rosenfeld = √√Trotsky ×× Bohr. Rosenfeld's particular views appear anomalous to the frequently expressed stereotypes of both Marxism and complementarity. The paper concentrates on the role Marxist philosophy played in Rosenfeld's fierce defense of complementarity from the late 1940s through the 1950s and the reception his campaign was accorded at the Niels Bohr Institute in Copenhagen and elsewhere.

Abstract A previously unpublished manuscript by the physicist Max Born, one of the creators of quantum mechanics, is presented. The manuscript was addressed to Born's colleague Léon Rosenfeld and criticized his attempt to show that Niels Bohr's doctrine of complementarity was an example of dialectical materialism and as such in perfect agreement with Marxist philosophy. Besides illustrating the deep political divisions among defenders of the ‘Copenhagen spirit’ in quantum physics, the manuscript is also a valuable source illuminating Max Born's philosophical position about scientific methodology and epistemology.

Leon Rosenfeld was a close collaborator of Niels Bohr's, with whom both Hugh Everett and John Wheeler discussed Everett's work. After the initial debate with Bohr and his collaborators, during which nether side was convinced of the other's position, Rosenfeld took the role of defender of the faith. In a series of letters to various physicists, Rosenfeld harshly criticized Everett and his work. Here Rosenfeld reports the Copenhagen line on Everett's thesis to an industrial physicist in Massachusetts.

Soviet attitude towards Bohr reflects changes in the ideological approach to science. During the last period before Stalin's death Ždanov 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.

According to the standard view, the so-called ‘Copenhagen interpretation’ of quantum mechanics originated in discussions between Bohr and Heisenberg in 1927, and was defended by Bohr in his classic debate with Einstein. Yet recent scholarship has shown Bohr's views were never widely accepted, let alone properly understood, by his contemporaries, many of whom held divergent views of the ‘Copenhagen orthodoxy’. This paper examines how the ‘myth of the Copenhagen interpretation’ was constructed by situating it in the context of Soviet Marxist critique of quantum mechanics in the 1950s and the response by physicists such as Heisenberg and Rosenfeld.

This book explores the modern physicist Niels Bohr’s philosophical thought, specifically his pivotal idea of complementarity, with a focus on the relation between the roles of what he metaphorically calls “spectators” and “actors.” It seeks to spell out the structural and historical complexity of the idea of complementarity in terms of different modes of the ‘spectator-actor’ relation, showing, in particular, that the reorganization of Bohr’s thought starting from his 1935 debate with Einstein and his collaborators is characterized by an extension of the dynamic conception of complementarity from non-physical contexts to the very field of quantum theory. Further, linked with this analysis, the book situates Bohr’s complementarity in contemporary philosophical context by examining its intersections with post-Heideggerian hermeneutics as well as Derridean deconstruction. Specifically, it points to both the close affinities and the differences between Bohr’s idea of the ‘actor-spectator’ relation and the hermeneutic notion of the relation between “belonging” and “distanciation.”

SUMMARY. — This paper emphasizes the evolution of complementarity, in Niels Bohr's successive formulations of this idea, from 1927 to 1939, despite little, if any change in the definition of the concept with time. In the Como lecture, in 1927, Bohr introduced the idea of « complementary descriptions » in a problematic, polemical way. Against Schrödinger' s interpretation, he stressed the « irrationality » inherent in the quantum postulate. In 1935, Bohr again used complementarity polemically, in his reply to Einstein-Podolsky-Rosen. But far from intending it to convey irrationality this time, he meant to use it instead to prove that quantum mechanics is a complete theory. Finally, I will take up Bohr's attempts to apply complementarity to fundamental problems in biology, psychology, sociology, and so forth. I will argue that the introduction of complementarity outside physics was not motivated by an imperialist ambition of the Copenhagen School, but rather inspired by Bohr's own personal philosophy.