Jean-Philippe Martinez and Jan Lacki, Uni Genève
Nowadays Fock is a familiar name to many physicists, especially those busy with quantum theory. The Hartree-Fock method of approximation for the determination of the wave function in many-body problems or the Fock space used to describe quantum states in situations where the number of particles is not fixed, are recognized as fundamental contributions to quantum physics. Those interested in relativity theory will instead remember his contributions to the motion problem in general relativity and possibly his unorthodox views on its interpretation. But only a few know more about the man behind the name and his fight on the behalf of quantum theory and relativity in Soviet Union. Indeed, Fock used his prominent position to promote in his country the two fundamental theories of 20th century and to protect them from undue ideological attacks.
Vladimir Fock was born in 1898 in Saint-Petersburg. Graduated in 1922 of the physico-mathematical faculty of the University of Petrograd 1, he made his entire career there, becoming first a PhD student, then a docent and finally a Professor in 1932. He obtained in 1927 a Rockefeller grant 2 to work with Max Born in Göttingen. Stimulated by the emulation of the Copenhagen school he found there the ideal ground to develop a rare combination of strong physical intuition and deep mastery of mathematical tools. Back in Soviet Union he made his fundamental contributions to quantum mechanics (Hartree-Fock method, 1930, Fock space, Dirac-Fock-Podolsky formalism of quantum electrodynamics 1932, etc.), and later to general relativity (the spinor field in a gravitational field, 1929, the problem of motion, 1939) 3. In 1939 he was also elected full-member of the Academy of Sciences of the USSR. Beyond his purely scientific achievements, Fock played a key role in popularizing quantum and relativity theories in Soviet Union: there is his 1932 publication of the first textbook on quantum theory (Foundations of quantum mechanics) 4; and later in 1955 a very important monograph on the theory of relativity, The theory of space, time and gravitation5.
Any historical study of Soviet science in the times of Fock has to take into close account its ideological and political context. 1929 marked in USSR the beginning of the so-called ''Great Break'': rapid industrialization, collectivization of agriculture and the beginning of specific cultural policies, all this mirroring the generalization of the idea of the ''construction of socialism'' 6. As a result, physics and physicists (among many others) came under close scrutiny and underwent criticisms. Of course, the ideological pressure was more or less strong over the years, but, as we shall see, severe controversies popped up in many debates.
The official philosophy of the regime, dialectical materialism, was based, to make it short, on the assertion that the existence of matter is separate and independent from mind. Consequently, idealism, positivism and the philosophical positions of their prominent representatives, Richard Avenarius, Ernst Mach and his many disciples to quote a few, were harshly criticized. Following the trend, Marxist philosophers, often with little or no training in physics at all, did not hesitate to attack the non-classical physical theories accusing Einstein and Bohr, their main creators and promoters, of all the sins of the erroneous philosophies.
Memorable clashes such as the one between the biologists Lyssenko and his opponent Vavilov 7, retrograde opinions such as those of physicist Timiryazev 8, or still the tragic fate of many scientists during the "Great Purge" 9 would suggest that Fock had to make a clear-cut choice between rejecting modern theories, in accordance with dialectical materialism, or continuing their investigation at the price of keeping low profile and refraining expressing his opinions publicly. The picture is more complex and surprising. In the early thirties, Fock was actually a supporter of dialectical materialism, but he remained faithful to quantum mechanics and general relativity, not a small feat in these troubled times! He held indeed a very peculiar position in the Soviet landscape because, in each controversial case, he managed to develop a specific interpretation of the theory under criticism that allowed him to prove it after all compatible with the dominant ideology.
Fock as an engaged scientist
According to testimonies, Fock studied and adhered to dialectical materialism at the beginning of the thirties (he read at that time Lenin, Engels and probably Marx as well). During that decade one can observe a subtle shift from his stand as a pure scientist to that of a resolute actor of philosophical, social and political struggles. Fock’s evolution appears retrospectively catalyzed by a dispute started in the main scientific journal dedicated to physics in Soviet Union, the Uspekhi Fizisheskikh Nauk (Progress of the physical sciences). In 1937, Fock had indeed published a criticism of the statistical conception of quantum theory developed by his colleague Nikolskiy 10. In spite of the fact that Fock's criticism was based on the mathematical formalism of quantum mechanics and on related facts and argumentations, Nikolskiy did not hesitate to fire back using instead the purely ideological rhetorics of the regime:
Beyond the fact that the conception of quantum mechanics, developped by Niels Bohr, is totally incompatible with the progressist orientation of theoretical physics, it is constantly accompanied of idealism, in the conception of Mach. This conception is very persistant, and systematically protected here by M. P. Bronshtein (Leningrad), L. D. Landau (Kharkiv) , I. E. Tamm (Moscow) and V. A. Fock (Leningrad) 11.
Nikolskiy’s answer, loaded with ideology but published in a scientific journal devoted in principle only to purely scientific matters, shocked deeply Fock. He was a man of principles, rigorous both in his work as in his life. No wonder that he answered bluntly that he refused to continue such a debate 12. But Fock was also proud and courageous 13 and Nikolskiy’s ideological attack led him to reconsider his strategy of publication. As a result, he started to publish his ideas in philosophical journals as well.
Among the latter, one of the most influential at the time was Pod Znamenem Marksisma (Under the banner of Marxism). Its chief-editor was Alexander Maksimov, a prominent Marxist philosopher of science. When Maksimov proposed Fock to use his journal to denounce the ''idealistic views held by eminent scientists'' or to comment on ''the main theoretical problems of modern physics'', the result went, least to say, much beyond Maksimov’s expectations… Published in 1938, Fock's paper ''On discussions on questions of physics'' was not only a resolute defense of the Copenhagen interpretation and an attempt to prove its compatibility with dialectical materialism but also a denunciation of the action of marxists philosophers against modern science. That article led naturally to a dispute with Maksimov which was stopped only by the events of the Second World War. The post-war period did not see a calm-down of the ideological debates. On June 24, 1947, Andreï Zhdanov, third secretary of the Communist Party of Soviet Union made a speech which marked the beginning of the most intense ideological campaign in the history of Soviet science, the Zhdanovshchina. The intervention of this major political authority was indeed perceived by Marxist philosophers as a clearance to be more aggressive and radical in their attacks against nonconformist views 14. In 1952, the book Philosophical Problems of Modern Physics15, edited by Maksimov and published by the Academy of Sciences of USSR, condemned firmly the philosophy of the “Copenhagen” school and called as well for a rejection of relativity theory. Fock did not wait long to react. He first managed to obtain from the Academy of Sciences a statement that the opinions expressed in Maksimov’s book were not mirroring the official position. Next, he published in Voprossy Filosofy16 (Questions of philosophy) a virulent article, ''Against the ignorant criticism of modern physical theories'' 17 that denounced the incapability of Soviet philosophers to deal with scientific subjects.
Criticizing Einstein’s general theory of relativity for the sake of Einstein’s theory of gravitation
Many attacks aimed at relativity in Soviet Union were indeed of rather poor intellectual content, originating most often from incompetent people with a shallow if not wrong understanding of the theory. Relativities of length, time or simultaneity was flatly condemned, simply because of their postulated incompatibility with the objective materiality of the world required by Soviet philosophy. The question of the existence of a world independent of our sensations led, on the other hand, to frequent criticisms directed against western commentators of general relativity, Arthur Eddington, James Jeans or Philipp Frank to quote a few. Einstein’s views were criticized as well because of the alleged influence exerted on him by Mach’s philosophy. Soviet philosophers, following Lenin’s claims against the Austrian scientist-philosopher, could not help but viewing the theory of relativity as a perfect expression of Mach’s idealism.
As we already hinted at, Fock was a supporter of Einstein’s theory. He was introduced to relativity theory while still a student thanks to the teachings of his masters Friedmann and Frederiks at Leningrad University at the beginning of the twenties 18. Over the next fifteen years Fock’s scientific activity was almost exclusively focused on quantum theory and he turned again to relativity problems only at the end of the thirties (this is when he obtained some of his main results in general relativity). Meanwhile, he had become a supporter of dialectical materialism and this had direct effects on his contemporary understanding of general relativity. The introduction of Fock's monograph on the theory of relativity makes this very clear:
The philosophical side of my views on the theory of space, time and gravitation was formed under the influence of the philosophy of dialectical materialism. [...] The teaching of dialectical materialism [...] helped me also to understand correctly, and to interpret, the new results obtained by me 19.
This quote seems to indicate that dialectical materialism was for Fock more than an a posteriori intellectual framework where he construed his philosophical views on space, time and gravitation. It hints indeed at a methodological guidance directly exerted on Fock's research. A closer inspection of Fock’s contributions to relativity shows this guidance in the requirement to analyze rigorously every concept involved in the theory. This is what led Fock to a sweeping criticism of Einstein's own understanding of general relativity. Indeed, Fock developed a very personal point of view on what Einstein’s theory really was (and was not), a position that he defended until the end in spite of the skepticism of his colleagues both in the East and West (albeit not always for the same reasons).
The main point of Fock’s criticism is that general relativity is actually no "general" at all: the general principle of relativity not only is not a generalization of the special (1905) one, but has rather to be considered as a restriction of the latter. This has to be understood in the following way. Fock’s conception opposes the "homogeneous" space-time of Minkowski with the “inhomogeneous” one of Einstein. The homogeneous case is physically characterized by the absence of privileged points in space and time, of privileged directions as well as of privileged inertial frames. Mathematically, this is expressed by the Lorentz group being the invariance group of the pseudo-euclidean Minkowski metric. This is an example of a more general situation where space-time admits a transformation group, a situation which commands that its curvature must be constant. In the inhomogeneous "Einsteinian" space-time, on the contrary, there is no such transformation group.
Now, for Fock, the assessment of "relativity" is naturally connected with uniformity of space and time: Lorentz invariance enables one indeed to speak of relativity of position (invariance under translations), direction (rotations) and of absence of privileged observation frames (Lorentz boosts). Given that Lorentz invariance, as a transformation group invariance of space and time, is lost in the inhomogeneous case, there is consequently no way to speak of relativity left alone of general relativity: "in the theory of nonuniform space-time, there is no principle of relativity […] If one uses the word relativity consistently, then the general principle of relativity is nonsensical" 20. Consequently also, the requirement of general covariance is not crucial to the theory as neither is the principle of equivalence. Fock did grant the latter a heuristic value in the discovery of general relativity but he did not consider it instrumental to the physical meaning of it. To resume, Fock used to say that "the physical relativity is not general; the general relativity is not physical". So what did Fock understand by "Einstein’s theory"? Well, it was for him a mere, albeit very successful and impressive, theory of gravitation.
All this explains that while defending relativity theory against the Soviet ideologues, Fock did not hesitate in the fifties to attack directly Einstein’s views 21. One of the most peculiar expressions of his criticism of Einstein was an article published in the Pravda22 in 1956 untitled "Half a Century of a Great Discovery. On Albert Einstein's Theory of Relativity" 23. While this article was highlighting the successes of the theory of special but also general relativity, it was as well criticizing Einstein’s deep misunderstanding of the real signification of the theory and promoting Fock’s own interpretation. The article gave rise to an interesting exchange between Fock and Igor Tamm 24: Tamm judged it inappropriate, especially given the jubilee circumstances, but Fock gave the following justification:
[…] I had to mention the erroneous philosophical declarations of Einstein. To occult them would be a tactical error. The only manner to give the theory of relativity (but also quantum mechanics) immunity against the attacks of philosophers, is that the physicist himself recognize the philosophical errors of the author of the theory, and separate these errors from the substance of the theory 25.
Fock’s conclusion was that what really mattered was that the publication of his article in a newspaper such as Pravda, known to represent the official line of the regime, had to be considered as an official recognition of the theory, "a great discovery and expression of human genius". Fock’s answer to Tamm makes his tactics clear: in the ideological context of Soviet Union, the defense of modern theories, to avoid a frontal clash with dialectical materialism, could not spare alternate expositions, interpretations and even revisions of some of their concepts. Disagreeing with Einstein and putting forth his own interpretation highly influenced by dialectical materialism was just Fock’s way to protect Einstein’s theory from ignorant criticisms.
Criticizing Bohr’s philosophy for the sake of Bohr’s complementarity
We just saw how Fock, while fully accepting the mathematical core of the general relativity, challenged Einstein’s interpretation of the theory. Fock adopted a similar attitude with respect to quantum mechanics that he defended against the attacks of the ideologues of his country while rejecting nonetheless some aspects of Bohr’s "orthodox" interpretation. The latter was judged guilty of the charge of positivism and non-objectivity because of the importance it gave to observation. In fact, the "Zhdanovshchina" period was sometimes significantly called "the age of the banishment of complementarity" 26. It saw increased attention, in Soviet journals, given to papers from Blokhintsev, de Broglie, Vigier, and Bohm, all proposing alternative interpretations of quantum mechanics. In historical investigations of the confrontation of quantum theory with Marxism, one tends to focus indeed on such interpretations (dubbed "statistical") to illustrate the attempts that have been made to reconcile quantum mechanics with the dominant ideology. Such focus oversees the fact that Fock tried to do the same without however denying the general framework of Bohr’s philosophy, which makes Fock, retrospectively, a distinguished (albeit special) Russian representative of the Copenhagen school.
Contrary to debates over relativity theory, those stirred by the Copenhagen interpretation of quantum mechanics were of a higher scientific standard, not least because, besides philosophers, there were also more physicists involved in the controversy. As we know from the "Nikolskiy's affair" mentioned above, Fock rejected statistical interpretations. According to Fock, the wave function enables to obtain the theoretical distribution of probabilities for a physical quantity and the probabilities so obtained have, on the other hand, an intrinsic (objective) meaning, in the sense that one can attribute probabilities to single events. In this context, statistics are to be viewed only as a way to test such probabilistic hypotheses. On the contrary, in a "statistical" theory (interpretation), probabilities intervene because of the absence of a (more) complete knowledge of the state of the system. Fock considered thus that statistical interpretations were only attempts "to invent a deterministic, subatomic and subelectronic mechanism in a way that a statistic applied to hypothetical movements of this mechanism would, on average, give the same results as statistical probabilities based on quantum mechanics " 27.
How did Fock match his scientific belief, namely that the quantum state provides a complete knowledge, with his philosophical materialistic - realist principles? This is where Fock gave his Copenhagen orthodoxy a peculiar twist with the help of what he called "mentally interrupted experiments" and probabilities of "virtually possible facts". Fock considered here, following Bohr, the emblematic case of a particle passing through a double slit in a diaphragm. If the latter is suspended in its plane, one can measure its position when the particle passes it, or measure the momentum exchanged between it and the particle after the particle has passed it (but one cannot do both). In the latter case, one can deduce which slit the particle went through (the upper one if the gain in momentum of the slit system was upwards, the lower one otherwise), but, because the position of the slit during the passing is unknown, one loses the interference pattern on the screen past the slit system. In the first case, the position of the diaphragm is known and this case is then equivalent to a rigidly fixed diaphragm with, consequently, an interference pattern visible.
As long as one does not decide what to measure, one is facing what Fock calls a "mentally interrupted experiment", a situation he judged crucial when interpreting quantum mechanics 28. Indeed, the important point here is that there are different ways to end up the experiment (by choosing what will eventually be measured). In each case, quantum mechanics will enable to compute a set of probabilities for the corresponding physical quantity and this computation will be done starting from the same wave function (before the particle hits the setup) corresponding to the initial conditions. The same wave function hence accounts for all the observables that one can measure starting from the initial conditions, i.e. for all the virtual modifications of the setup in the very last stage of the experiment. This implies that, in defining the quantum state of a system as given by its wave function, it is possible to make abstraction of the last state of the experience, the effective setup and the resulting measurement:
The quantum state of the system relates then to what is virtually possible and not to what is effectively done. The wave function enables to compute, starting from given facts, the probabilities of other virtually possible facts 29.
This position enabled Fock to state that the wave function, and hence quantum mechanics, were an objective description, objective in the sense of independent from the last stage of the measurement (observation) hence, independent of the "observer", a major requirement to reach compatibility with dialectical materialism.
Fock’s rather elegant argument for the objectivity of the quantum description was not, however, sufficient to lift the criticisms directed against Bohr’s views on quantum theory. Fock hoped initially to bridge the gap between the Copenhagen doctrine and dialectic materialist philosophy using a linguistic reassessment of Bohr’s writings. The following excerpt from a letter Fock send to Léon Rosenlfeld makes this clear 30:
[...] I am convinced that despite his slightly positivist language, Bohr believes as much as we do in the reality of phenomena of which he speaks, and then the difference between the views of Bohr and mine is more a difference of language than a difference of content 31.
It occurred eventually to Fock that he could not defend Bohr against the charges of idealism without revising the latter’s interpretation of quantum mechanics. Indeed, Fock was genuinely disturbed by the positivistic overtones of Bohr's philosophy and in particular the use the latter made of two key notions, "causality" and "uncontrollable interaction". In what concerns causality, Bohr used it as an expression of the energy-momentum transfer description of phenomena, contrasting it (in the complementarity doctrine sense) with the space-time one. Because of the incompatibility of the relevant experimental setups (expressed formally by the Heisenberg relations), Bohr declared that one had, in given circumstances, to give up the causal description. Such a statement was highly incompatible with dialectical materialism. On this point Fock simply pointed out that this conception ("giving up the causal description") was valid only if causality was narrowly understood in terms of laplacian determinism. Causality in a broader sense was however preserved.
In what concerns the thesis of "uncontrollable interaction'', things were more involved. It was Bohr’s way to describe the relation between the measurement device and the atomic object in the case when the existence of a "quantum of action" (the finite value of Planck’s constant) could not be neglected. Considering that every physical interaction is by definition controlled, Fock rejected the idea of uncontrollability at the physical level and suggested rather that Bohr’s "uncontrollability" thesis had to be construed in purely logical terms when analyzing the measurement process.
Fock and Bohr could confront directly their views during a sojourn Fock did in Copenhagen at the beginning of 1957. Fock judged the meeting fruitful since, as he reported, Bohr declared that "he is not positivist and only tries to consider nature as what it is" 32. Bohr’s plain and public answer to the criticisms mentioned above followed in his 1958 article entitled ''Quantum Physics and Philosophy'' 33. In particular, in what concerned the idea of an ''uncontrollable interaction'', Bohr recognized there that the question was subject to debates and possibly involved a logical aspect:
[…] the use of phrases like "disturbance of the phenomena by observation'' or ''creation of physical attributes of objects by measurements'' is hardly compatible with common language and practical definition. In this connection, the question has even to be raised whether recourse to multivalued logics is needed for a more appropriate representation of the situation 34.
While Bohr’s article remained a strong defense of complementarity, it was incorporating nonetheless some linguistic readjustments and was claiming the objectivity of the theory. As a result, its reception in Soviet Union was quite positive as Fock reported to Rosenfeld:
This article is very appreciated in Russia because it contains very important statements on causality, objectivity, etc., which reconcile Bohr’s views with the dialectical materialist point of view duly formulated 35.
Indeed, one could witness at that time an inflection in the perception of Bohr's ideas in USSR. The late fifties were seeing a slight return to freedom of expression while ultraorthodox philosophers or representatives of pseudo-science as Maksimow were losing much of their influence. Fock took opportunity of this change to promote the Copenhagen interpretation in a more offensive way. He tried, on one hand, "to silence" the "de Broglie-Bohm-Vigier theory" qualified as "simply absurd" 36, and, on the other, to popularize Bohr's work. After his 1959 translation of Bohr’s "Quantum Physics and Philosophy" for the journal Uspekhi fizicheskikh nauk, Fock worked on a Russian version of Atomic Physics and Human Knowledge, a compilation of articles published by Bohr in 1958. This version 37 contains, on Fock’s specific request, two additional articles with respect to the original, "Quantum Physics and Philosophy" and "Quantum Physics and Biology". Devoid of any positivist expressions, these articles were for Fock the promise of a favorable reception of the book in his country.
Fock’s "double-faced" tactics had worked again: his qualified support of the Copenhagen interpretation very much helped to rehabilitate Bohr in USSR. After more than twenty years of suspicion, the Dane was invited in 1961 by the Soviet Science Academy: he spent two weeks in Soviet Union to great effect. After Bohr’s death the journal Uspekhi fizischeskikh nauk dedicated a special issue to his memory. In the same period Fock's unorthodox interpretation of the theory of relativity was receiving special attention, both in his country and abroad 38. Thanks to a deep reflection on the interpretation of these theories from a dialectical materialist point of view, Fock had become their best critic and at the same time their best proponent.
In spite of a difficult political context, Fock always managed to remain faithful to his scientific and ideological beliefs. Beyond the value of his views on the interpretation of modern theories, Fock is a very interesting character in history of science. His longevity and his first rate involvement in frontier physics is of great value when studying Soviet science beyond the clichés often associated to it. More generally, his intellectual trajectory makes an appealing case study of how a scientist deals with pressing philosophical and political questions.
1 The name of Saint-Petersburg changed two time at the beginning of the twentieth century. It became Petrograd in 1914 and Leningrad in 1924.
2 That grant was awarded to Fock partly because of his work, quasi-simultaneous Oskar Klein’s, on the equation know today as the Klein-Gordon equation.
3 Fock V. A. - ''Sur le mouvement des masses finies d'après la théorie de la gravitation'', Journal de Physique (URSS), Vol. 1, N°2 (1939), p. 81-116.
4 Fock V. A. - Nachala kvantovoy mekhaniki, Leningrad, Izdatel’stvo KUBUCH, 1932, 251 p.
5 Available in english: Fock, V. A. - The theory of space, time, and gravitation, 2nd rev. ed, translated from the Russian by N. Kemmer, New York, Macmillan, 1964, 448 p.
6 For a more general vew of science and politics in USSR, see Krementsov N. - Stalinist Science, Princeton, Princeton University Press, 1997, 372 p.
7 Trofim Lyssenko is known for his pseudo-scientific genetic theory claiming the possibility to modify genetic characteristics thanks to environment modifications. He succeeded on promoting his theory as a state doctrine while his opponent Nikolaï Vavilov, defending mendelian genetics was sentenced to death in July 1941. Even if his sentence was commuted to twenty years' imprisonment, he died in prison in 1943.
8 Arkady Timiryazev was a professor of the State University of Moscow known for condemning both the quantum and relativity theories because of their alleged idealistic stance.
9 Among them we can mention Matvei Bronstein, or the future 1962 Nobel prize winner Lev Landau arrested in 1938 and jailed for one year. Fock himself was arrested twice but “only” for a few hours the first time, and four days the second one.
10 Fock V. A. - ''K stat'ye K. V. Nikol'skogo: Printsipy kvantovoy mekhaniki'' (On the article of K. V. Nikolskiy: Principles of quantum mechanics), Uspekhi Fizisheskikh Nauk, Vol. 17, N°4 (1937), pp. 552-554.
11 Nikolskiy K. V. - ''Otvet V. A. Foku'' (Answer to V. A. Fock), Uspekhi Fizisheskikh Nauk, Vol. 17, N°4 (1937), p. 555.
12 Fock V. A. - ''Pis'ma v redaktsiyu'' (Letter to the redaction), Uspekhi Fizisheskikh Nauk, Vol. 19, N°4 (1938), pp. 139-140.
13 During the Great Purge he is reported to have stated: "Cowardice does not influence the probability of arrest".
14 Shortly after Zhdanov’s speech the physicist Mosey Markov, defending the principle of complementarity, became the object of very virulent attacks.
15 Maksimov A. A. (ed.) - Filosofskiye voprosy sovremennoy fiziki (Philosophical problems of modern physics), Moscow, AN SSSR, 1952, 576 p.
16 This was the new name of Pod znamemen marxisma, still one of the most influential philosophical journal.
17 Fock V. A. - ''Protiv nevezhestvennoy kritiki sovremennykh fizicheskikh teoriy.'', Voprossy filosofy, N°1 (1953), pp. 168-174.
18 See the very informative paper by Gennady Gorelik, “Vladimir Fock: Philosophy of Gravity and Gravity of Philosophy”, in: The attraction of gravitation: new studies in the history of general relativity, J. Earman, M. Janssen, J. Norton (eds), Boston, Birkhäuser, 1993, pp. 308-331.
19Op. cit. n°5, p. 8.
20 Fock V. A. - ''Three Lectures on Relativity Theory'', Review of Modern Physics, Vol. 29 (1957), p. 326 (325-333).
21 Fock’s conception of Einstein’s theory definitely requires a more detailed account, especially his understanding of Einstein’s equations and the associated boundary conditions, as well as the crucial role he attributed to the so-called « harmonic coordinates ». The interested reader is referred to the paper of Gorelik mentioned above (note 20).
22Pravda was at the time the main official soviet newspaper.
23 Fock V. A. - ''Polveka velikogo otkrytiya. O teorii otnositel’nosti ?l’berta Eynshteyna'', Pravda, 15 avril 1956, N°106.
24 Igor Tamm was a Soviet theoretical physicist working in Moscow, a Nobel laureate in 1958 with Ilya Frank and Pavel Cherenkov for their discovery and interpretation of Cherenkov radiation.
25 Letter from Fock to Tamm, 17th of novembre 1955. ARAN SPb 1034-3-160.
26 Graham L. - Science and philosophy in the soviet Union, New-York, Alfred A. Knopf, 1972, p. 80.
27 Fock V. A. - ''Critique épistémologique de théories récentes'', La Pensée, Paris, N°91 (mai-juin 1960), p. 15 (8-15). See also Fock’s article directed specifically against Blokhintsev’s views: ''On so-called 'ensembles' in quantum mechanics'', Voprossy filosofy, N°4 (1952), pp. 170-174.
28 To be compared with what is called today a "delayed choice experiment"
29 see reference note 27, p. 12.
30 The Belgium physicist Léon Rosenfeld, one of the closest collaborators of Bohr in Copenhagen, was also known for being a fervent marxist.
31 Letter from Fock to Rosenfeld, 7th of April 1956. ARAN SPb 1034-3-145.
32 Fock V. A. - ''Poyezdka v Kopengagen'' (Visit to Copenhagen), Vestnik ?kademii nauk SSSR, N°7 (1957), p. 56 (54-57).
33 Bohr N. - ''Quantum Physics and Philosophy'', in: Philosophy in the mid-century, Raymond Klibansky (ed), Florence, 1958, pp. 308-314.
34Ibid, p. 313.
35 Letter from Fock to Rosenfeld, undated. ARAN SPb 1034-3-145.
36 Letter from Fock to the redaction of Uspekhi fizicheskikh nauk, 2nd of September 1958. ARAN SPb 1034-2-219.
37 Bohr N. - ?tomnaya fizika i chelovecheskoye poznaniye, translated into Russian by V. A. Fock and A. V. Lermontovoy, Moscow, Izdatel’stvo inostrannoy literatury, 1961, 151 p.
38 As testimony of his influence at that period we can note that Fock was the president of the International Committee on General Relativity and Gravitation in the years 1968-1971.
[Published: July 2015]