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p Since the time of Galileo, the identifying of the concepd ‘observation’ and ‘measurement’ in physics has provet in a certain respect justified, because physics became (and will forever remain) a quantitative or, as it is said, an exact science. Something similar happened in quantum mechanics in which, from Bohr’s day, the interaction of a ’classical object’, called in a certain connection an instrument, with a ’quantum object’ (e.g. the electron) is spoken of as 304 measurement. It is noted that this interaction occurs independently, and without the participation, of an observer. In Landau and Lifshitz’ excellent course of theoretical physics one can find precisely such a statement, and there are as many as you like in the literature on quantum mechanics.^^62^^

p Such identifying of ‘interaction’ and ‘measurement’ in quantum mechanics (frequently discussed in the works of Bohr, Heisenberg, and the other founders of this physical theory) also has its definite content and meaning from the philosophical (logical and epistemological) aspect. This is also often mentioned in current literature on quantum theory. Their analysis, which is the task of this chapter, should certainly present interest in more than a ’quantum- mechanical’ respect.

p Let us discuss the interaction itself of the measuring instrument and the measured object to begin with. Any measurement, and not just in quantum mechanics, always implies the possibility of a reciprocal change of the state of the instrument and of the object. (1) Without a change of the instrument’s state nothing would be known about the measured object; (2) the very process of measurement can affect its result. This possibility is realised in certain conditions, since both the measuring instrument and the measured object are physical realities (physical objects) and there is force effect between them (with transfer of momentum, energy, or both, from the one physical object to the other).

p Are we dealing with that kind of interaction in quantum mechanics?

p When it is a matter of measurement in classical physics, the very essence of the measurements necessitates existence of the concept of a force effect in the theory of the appropriate measurements. The interaction of the instrument and the object, which is practically inseparable from the measurement itself, affects its result; in classical theory, however, this influence can be abstracted in the final analysis, and ignored, since the force interaction of the measuring instrument with the object measured can be arbitrarily small in principle (which is reflected in the theory of the processes being studied). If we want to measure accurately the temperature of the water in a container by a thermometer, for instance, we must allow for the change in the water’s temperature as a result of immersing the thermometer in it. But, on the basis of the theory of heat exchange, we can draw a 305 conclusion about the water’s temperature before the thermometer was immersed in it from the thermometer readings, i.e. ’get rid’ of its distorting effect on the water’s temperature.

p The situation with measurement in quantum mechanics would seem to be exactly the same. Let us assume that an electron flux (from an electron gun) passes through a crystal, and that the electrons hitting a screen produce scintillations that form a diffraction pattern. De Broglie’s wavelength and, consequently, the electron’s momentum before passing through the crystal, are determined from this pattern, i.e the data of the diffraction experiment, plus quantum theory, allow us to infer the electron’s state before the crystal that altered it was used.

p And yet, while the formal structure of measurement is the same in classical theory and in quantum mechanics, their essential content is profoundly different. It was not fortuitous that there was such an intense polemic around the problem of measurement in quantum mechanics. The point is that quantum mechanics is a radically new theory, as regards its foundations, compared with classical theories, including relativistic physics; it contains the concept of the wave function  [305•*  (in our second example it is expressed by de Broglie’s wave), specific to its theoretical content, and since measurement is impossible without applying the theory of the phenomena being studied to the instrument readings, the difference between the content of ‘quantum’ and ‘classical’ measurement becomes clear from that.

p We would emphasise once more that any measurement, since it is based on experiment, is inconceivable without a force action (effect) of the measuring instrument (device) on the object measured; the problem in measuring an object is in fact to get rid of the outside influences, external to the measured object itself (and its inherent quantitative characteristics), that distort the measurement result. In that one cannot do without the theory of the respective phenomena, and 306 some or other of its principles: in this case they are intended, so to say, to clear the result of measuring a quantity of everything that is not proper to the measured quantity itself (in the context of the theory of the relevant phenomena), i.e. to obtain thereby an adequate expression (in certain measures) of the quantity itself (the parameter of the object measured).

p As already noted, it was always possible in principle, in classical theory, to ‘exclude’ (eliminate) the relevant, effect of the measurement or observation, which meant exclusion of the measuring instrument and, therefore, in the end, of the observer, since the instrument is a kind of extension of the observer, his artificial organ of cognition. In this case the sting is not that the physicist can make the instrument, but that the object serving as an instrument is linked, as it were, by the physicist to his sense organs thus, so to say, ‘extending’ his brain.

p It seems to us that this ’classical path’ of understanding of measurement was actually also followed by quantum mechanics in the first stages of its construction as a physical theory. Such a ‘classical’ beginning of the understanding of measurement in quantum mechanics was inevitable not just historically. As we shall see later, however, the development of this understanding proved to be quite unique, resembling, at first glance, the development of the problematics of measurement in classical physics but characterised, in fact, by a content unknown to classical physics.

p The famous imaginary experiment with an X-ray microscope conceived by Heisenberg so as to illustrate the physical meaning of the uncertainty relation, brings out the essence of the initial understanding of measurement in quantum mechanics which we arbitrarily called ‘classical’ above. From the standpoint of this experiment, the electron cannot be observed (its position cannot be determined) if there is no interaction between it and a photon (i.e. if it is not illuminated by light of a certain wavelength A,)  [306•* ; the momentum p = H/h transferred by the photon, however, introduces an’ uncertainty Ap_x   H/h into the electron’s initial momentum; as a result, increase in the accuracy of measurement of the electron’s position leads to a loss of accuracy 307 in the measurement of momentum AzAj^   h; in other words, the photon-electron interaction makes simultaneous accurate determination of the electron’s position and momentum impossible.

p Reasoning of this kind also contains the source of the idea of an uncontrollable (indeterminable) interaction between the measuring instrument and the micro-object; at one time this idea was regarded as the core of the conception of complementarity, and the dialectics of the atomic processes were revealed and at the same time obscured in it. We shall not dwell on the principle of uncontrollability (indeterminacy) (it has been extensively discussed in the physical and philosophical literature), but we would like once more to stress here that the conception of complementarity, in the sense of the accuracy and perfection of the terminology and reasoning (and consequently of the further development of the theory’s logic), is now very far removed from the formulations that can be found in the relatively early work on quantum mechanics. To this end, let us consider some of Bohr’s ideas.

p He spoke, in 1935, of ’the impossibility, in the field of quantum theory, of accurately controlling the reaction of the object on the measuring instruments, i.e., the transfer of momentum in case of position measurements, and the displacement in case of moment of measurements’.^^63^^

p And how did the uncontrollable interaction arise? We learn this from Bohr’s following considerations: ’The finite interaction between object and measuring agencies conditioned by the very existence of the quantum of action entails— because of the impossibility of controlling the reaction of the object on the measuring instruments if these are to serve their purpose—the necessity of a final renunciation of the classical ideal of causality and a radical revision of our attitude towards the problem of physical reality’.^^54^^

Thus, from this angle the interaction between the measuring instrument and the measured micro-object can be classified as a force effect that is, however, uncontrollable. The fact that classical physics does without an uncontrollable (force) effect can be explained by quantum of action’s being very tiny so that we are justified, when considering the interactions between macroscopic objects, in abstracting ourselves from its existence. On the other hand, when atomic phenomena are discussed, it is in principle impossible to neglect 308 the existence of the quantum of action (because of the smallness of the phenomena), so that it is necessary to assume that the effect in transfer of momentum or energy cannot be smaller than the value of the quantum of action and, consequently, that effect of the measuring instrument on the object cannot be reduced to nothing in measurement; these are considerations that cannot be by-passed from the standpoint of the idea of uncontrollability in principle. Discovery of the quantum of action thus seemingly leads inevitably to acceptance of the idea of uncontrollability in principle, and the quantum-mechanical probabilities, and the impossibility of separating the behaviour of an atomic object from its relation with the measuring instrument (in the study of phenomena) are seemingly necessarily linked internally with the uncontrollability principle. We shall now try to clarify whether this is true or whether the heart of the matter does not consist in the ’force effect’ between the atomic object and the measuring instrument.

p Bohr’s discussions with Einstein on the problems of the theory of knowledge in atomic physics can help us deal with the question posed. Bohr, as we know, could not convince Einstein of the fruitfulness of his interpretation of quantum mechanics when they argued about the resolving of the paradoxes posed by Einstein, although he always managed to demonstrate the inconsistency of these paradoxes and, therefore, that Einstein was wrong. A half-joking remark by Ehrenfest, who was a close friend of the two great physicists, has come down to us: ‘I’m ashamed of you, Einstein. You put yourself here just in the same position as your opponents in their futile attempts to refute your relativity theory.’^^55^^

p It seems to us that there is a deep meaning in all this. At that time in the arguments on quantum mechanics the term ’uncontrollability in principle’ was pushed to the fore with Bohr, in the meaning that was discussed above. The term ‘complementarity’, which also appears in his publications of that period, was not yet clearly separated from ’ uncontrollability in principle’ (as happened in his later works). The argument, properly speaking, was concerned with the content of the concept of the measuring instrument’s interaction with the micro-object and, as we shall show later, that helped solve the problem.

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p Einstein, in rejecting Bohr’s conception, denied the uncontrollability principle in the form in which it existed at that time in the development of quantum mechanics. Bohr, in defending his conception, advanced as its basis the complementarity principle, which was not then, however, clearly defined (it was the dispute in fact that promoted its definition) and got lost, as it were, in the idea of uncontrollability. It would be quite instructive to trace in detail the logic of the remarkable dispute between Bohr and Einstein on the philosophical positions of quantum mechanics. It is probable that it would then be found that Einstein was to some extent justified in disagreeing with the idea of the uncontrollable interaction, while Bohr, in defending his interpretation of quantum mechanics, also, in essence, did not support ’ uncontrollability in principle’, although he used the term. We shall make only some general brief comments to clarify this point.

p The essence of Bohr-Einstein discussion on the philosophical problems in quantum physics (which took place in 1935) consists in the following. If a system composed, say, of two electrons (which at some time were in a physical interaction  [309•* ) is characterised by means of the wave function, the effect associated with measuring the first electron alters the state of the second one even when it is very far removed from the first. Einstein saw a paradox in these statements, which accord with the content of quantum mechanics, since they are incompatible with the principle of short-range interaction which implies the existence of independent realities in two parts of space distant from each other. In his view, the answer to the paradox was to recognise that modern quantum mechanics gave an incomplete, indirect description of reality, which would later be replaced by a complete, direct one. The last comment was directed against the understanding of quantum mechanics that did not essentially distinguish between the states of micro-objects ( characterised by wave functions) and possible information about them, i.e. which converted micro-objects’ states into something very far from objective reality.

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p Such was Einstein’s paradox to which he returned in other publications.^^56^^.^^67^^ One cannot, however, agree with the solution he suggested; or rather, there is no paradox here, as Bohr demonstrated, although his argument does not appear satisfactory from the standpoint of the revised terminology and reasoning of his last works.

p Einstein was certainly right when he recognised the momentum and spatial characteristics of an atomic object, i.e. its quantum state, as objective, in other words, as existing independently of the instrument readings perceived by man; he was wrong, however, when he identified these characteristics in essence with classical concepts. An atomic object’s momentum and spatial characteristics do not appertain to the object as such but to it in certain conditions that are recorded by instruments of various kinds; the quantum state has something to do with the potential possibilities of an interaction between the object and the measuring instrument (which may be either, say, a cloud chamber or a diffraction device). The underlying philosophical reason for this state of affairs is that an atomic object does not behave either as a classical particle or as a classical wave but as a material system that unites the properties of particles and waves (fields) in a unique manner. The interaction of two such atomic objects considered by Einstein differs qualitatively from all interactions between particles or fields known in classical physics, and this is reflected by quantum mechanics.

p Fock regards the interaction between two atomic objects with a common wave function (the case analysed in Einstein’s paper) as a special interaction which he calls a nonforce one. He believes that Einstein was wrong when he renounced all interactions except the force ones.^^68^^ In reality, as he suggests, there are many different kinds of interaction both in science and in everyday life which are non-force ones.

p It is worth adding to what has been said about non-force interactions that the specific feature of the non-force interaction that figured in Einstein’s paradox was that it was not an interaction of particles in the sense of classical physics but of the micro-objects simultaneously possessing both corpuscular and wave properties.

p The understanding of the interaction between the measuring instrument and the measured atomic object as 311 uncontrojlable interference with a phenomenon, an understanding which was considered to form the basis of quantum mechanics, created an erroneous impression both of the content of this theory itself and of the new element that it contributed to philosophy. The idea of uncontrollability in principle is a distorted, exaggerated expression of the need to reflect in the logic of concepts something unexpected introduced into science by the development of atomic physics. The quest for these concepts or, in Bohr’s words, the perfecting of the terminology and argument, and the development of the formulation of the approach to the cognition of atomic phenomena that he described by the concept of complementarity, all this is discussed in his famous book Atomic Physics and Human Knowledge, the deep philosophical content of which, in our view, is still far from being assimilated.

p One can clearly trace in this book how Bohr (who never attributed decisive significance to formal schemes in logical analysis), surmounting the contradictions, came, not directly, but by a zigzag path, to a materialist and dialectical interpretation of quantum mecanics in order to become convinced in and steadily follow an already definite, clear philosophical road. Whereas, in his first articles (during the thirties and forties), when discussing the problems of quantum mechanics, he spoke not so much of the objective character of the quantum description as of the observer and ascribed to the idea of uncontrollability in the sense mentioned above the main role in establishing order in the apparent chaos into which physics had been plunged by the quantum theory, he changed his point of view, as is well known, in his last publications. The turning point in this respect was his paper Discussion with Einstein on Epistemological Problems in Atomic Physics (1949).^^59^^ One can clearly see in it the struggle between concepts that in time would leave the pages of his works and concepts that were in betterl accord with quantum mechanics andjits mathematical apparatus that was established and checked experimentally. Let us cite, in this connection, what seems to us the most lucid passage in this paper.

p In stressing the idea that no matter how far phenomena might go beyond the context of a classical physical explanation, the experimental data should be described by means of classical concepts, Bohr concluded that a sharp line could not be drawn between ’the behaviour of atomic objects and the 312 interaction with the measuring instruments which serve to define the conditions under which the phenomena appear’. Furthermore, he formulated an idea about complementarity that quantum effects were responsible for the impossibility of comprehending the ’evidence obtained under different experimental conditions ... within a single picture’; rather the evidence ’must be regarded as complementary in the sense that only the totality of the phenomena exhausts the possible information about the objects’.^^60^^

p When one puts together everything that Bohr said in his discussions with Einstein, and bears in mind the interaction between the measuring instrument and the micro-object, one has to note that this interaction is not a physical or force interaction. Fock in pointing out the unsatisfactory character of Bohr’s term ’uncontrollable interaction’ said: ’As a matter of fact, it is a matter here not of an interaction in the proper sense of the term but of the logical connection between the quantum and classical methods of description at the junction between that part of the system which is described in quantum-mechanical terms (the object) and that part which is described in classical terms (the measuring instrument).^>el

p Ideas of this kind led to the now well-known propositions that the classical conception about the motion (behaviour) of a particle is limited (this is expressed by the uncertainty relation), that there is relativity with respect to the means of observation characteristic of quantum mechanics, and that atomic objects are described through physical concepts that are more precise and general than those of classical theory. In this book it is neither possible nor necessary to set out the logical aspects of these considerations in greater detail, but we would like once more to emphasise that Bohr never tired of developing and logically perfecting the approaches to the cognition of atomic phenomena which he had defined through the concept of ‘complementarity’. Correct application of this concept, according to him, implied recognising that the interaction between atomic objects and the measuring instruments constituted an inseparable part of the quantum phenomenon, and not recognition of observation as ’interference with a phenomenon’.

p The following scheme summarises what has been said in this section about the interaction of the measuring instrument and the object measured.

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p Classical Theory. The force interaction and controllability. Einstein saw the ideal for the quantum theory as well in an understanding of measurement of this kind.

p Quantum Theory, a) Force interaction and uncontrollability (complementarity). This understanding of measurement in quantum mechanics was developed by Heisenberg and Bohr in the thirties and forties.

p b) Non-force interaction in the sense of a logical interrelation and uncontrollability (complementarity). This understanding of measurement in quantum mechanics was held by Bohr in 1949.

p c) Complementarity and relativity with respect to the means of observation. The concepts of controllability and uncontrollability have no meaning. This is the contemporary understanding of measurement in quantum mechanics.

It must be remembered that points (a), (b), and (c), when regarded on the historical plane, were not, so to speak, rigid.

p In conclusion, let us make a few comments on the role of the instrument in the theory of knowledge in relation to atomic physics, without which the content of the above may not appear concrete.

p We shall not consider the instrument here specially as the most important means for cognising physical phenomena; scientists are quite familiar with this question in practice; as for its theoretical aspect, that has been thoroughly analysed in the existing literature on physics, and it is not our business to go into the details of it. We would like simply to note that the natural shortcomings and limitations of the sense organs that supply us with information on the external world are surmounted in the cognition of nature, as we well know, by combining them with the activity of thought; the material expression of this is precisely that man makes and uses instruments.

p The progress of pure and applied science has led to the creation of a system of instruments, or experimental devices, unified into a single, organic whole that can be called a developed experimental set-up.

p Every developed experimental set-up usually includes four elements: (1) a recording device that fixes the phenomena in the instrument by which the objects being studied are judged; (2) apparatus that makes it possible for 314 phenomena not directly perceivable by a given sense capacity to be comprehended in a mediated way, through other phenomena that are directly perceivable by this sense capacity; (3) apparatus that expands the limits of perception of a given sense capacity; (4) an experimental device that supplies the energy to bring the recording instrument into the state in which it can perform its functions. The elements of a developed experimental set-up can be combined with one another, and the last three elements exist just so that the recording apparatus can best perform its task, i.e. fix the appropriate phenomena in the instrument.

p The experimentation implies, besides use of an instrument by which a phenomenon or object is studied (it figures above as an element of a developed experimental set-up; it can be called an instrument in the proper sense of the term), the realisation of certain conditions without connection with which the existence of the phenomena being studied cannot be discovered. These conditions are either sought in nature ( natural conditions: in this case experimentation passes into observation) or created by the experimenter by means of the appropriate experimental set-up. Examples of such setups are provided by the physics equipment and instruments of all kinds that either reproduce the appropriate set of phenomena or create conditions in the absence of which it is impossible to know anything, in a certain respect, about the phenomena being studied (e.g. vacuum equipment to study the properties of a gas in a strongly rarefied state; prisms to study light; diffraction devices and the cathode-ray tube to study electron behaviour). It can be called initial-state preparation apparatus  [314•*  and it also constitutes an element of a developed experimental set-up.

p To do its job the initial-state preparation apparatus is joined to the set-up proper and forms a united whole with it during the research.

p These two types of experimental apparatus cannot, however, be identified either physically or logically, although one can find cases in the literature where it is done. Fock has stressed the need to distinguish between them (in the terms 315 of the experiment) when it is a matter of measurement in quantum mechanics.^^62^^

p In classical theory the preparation apparatus provides the conditions in which the phenomenon being studied is least distorted by disturbing effects as yet unknown to the researcher. In quantum mechanics this apparatus creates conditions outside which, and independently of which, there can be no phenomena for cognising the corpuscular and wave aspects of an atomic object’s behaviour. Thus, we repeat, a part of the apparatus is included in the phenomenon, while the instrument proper is something external in relation to the phenomenon it serves to cognise.

p At the same time, the difference between the preparation apparatus (which belongs, in a certain respect, to the system observed) and the instrument proper (which in a certain respect cannot be separated from ourselves) should not be exaggerated; it is relative, not absolute. Bohr well understood that a sharp line cannot be drawn between the cognised object and the cognising subject, the system observed and the equipment used to observe it (he analysed many aspects of this question in nearly every one of his publications). One illustration that he gave himself is striking. If a blind man holds his stick firmly in his hand ’it can serve as a sort of prolongation of the latter to explore the surroundings by touch’. On the other hand, if it is held loosely, ’it becomes itself an object whose presence is revealed to the hand by the sense of touch, and it loses thereby its function of instrument of observation’.^^63^^

p Let us return to Heisenberg’s experiment with the X-ray microscope. The observer learns the electron’s position with an accuracy that is the greater the shorter is the light wavelength, i.e. light (with its wave properties) serves as a means of cognising the electron’s behaviour; the quantum properties of this same light (which represents a flux of photons), however, make it a sort of inseparable part of the electron’s cognised behaviour. In the end, the electron’s position and momentum prove to be complementary concepts.

p Still, the relative difference between the preparation apparatus and the instrument as a means of observation considered above, or, if the matter is considered more broadly, between the cognised object and the cognising subject, or, even more broadly, between matter and mind, is not a relative and only a relative difference. It was the understanding 316 of this difference as exclusively relative that lay at the philosophical foundation of the interpretation of quantum mechanics in which uncontrollability in principle, the idea that a wave function is a record of the observer’s information, was lauded to the skies by positivism and other idealist trends in contemporary philosophy.

p When we analyse philosophical concepts and statements appertaining to the problem of the interaction between the measuring instrument and the atomic object, we cannot avoid the basic philosophical question of the relation between matter and mind. In Materialism and Empiric-criticism Lenin developed Engels’ formulation of this question and stressed the absolute nature of the opposition between matter and mind within the context of the basic question of philosophy, namely, what should be taken as primary, and what as secondary. ’Beyond these bounds,’ he wrote, ’the relative character of this antithesis is indubitable.’^^64^^ This relativity which has been ’blown up’ by positivists and subjective idealists in a one-sided way, was not seen by representatives of metaphysical anti-dialectical materialism.

p Lenin’s ideas provide the necessary basis for successful quests for a solution of philosophical problems concerned with the relation between the cognising subject and the cognised object.

p REFERENCES

p  ^^1^^ Frederick Engels. Anti-Duhring (Progress Publishers, Moscow, 1969), pp 353-358.

p  ^^2^^ H. Lebesgue. Sur la Mesure des Grandeurs (L’Enseignement mathematique, Geneva, 1956), p 81.

p  ^^3^^ See Chapters III and IV, above.

p  ^^4^^ On the significance of definition for science, see Frederick Engels. Op. cit., p 98.

p 5 See K. B. Karandeyev, V. I. Rabinovich, and M. P. TsapenkoA Contribution to Defining the Concept of Measurement. Izmeritelnaya tekhnika, 1961, 12: 4-6.

p  ^^6^^ See, for example, E. Madelung. Die mathematischen Hilfsmittel des Physikers (Springer Verlag, Berlin, 1957), p 353.

p  ^^7^^ E. Nagel. Measurement. Erkenntnis, 1931, 2, 5-6: 315.

p  ^^8^^ See Nagel’s article in Erkenntnis cited above.

p  ^^9^^ A. N. Kolmogorov. Quantity. Great Soviet Encyclopedia (Second edition), Vol. 7 (Moscow, 1951), p 340.

317

p  ^^10^^ On the axiomatic construction of the theory of measurement of quantities, see also N. Bourbaki. The Architecture of Mathematics. The American Mathematical Monthly, 1950, 57. 7: 231.

p  ^^11^^ See M. F. Malikov. Osnovy metrologii (Fundamentals of Metrology), Part 1 (Committee for Weights and Measures, Moscow, 1949), p 315.

p  ^^12^^ Ibid., p 316.

p  ^^13^^ For examples see L. V. Cherepnin. Russkaya metrologiya (Russian Metrology) (Institute of History and Archives, Moscow, 1944), pp 22-26.

p  ^^14^^ Our example is taken from Volume I, Chapter I, of Marx’s Capital (Progress Publishers, Moscow), pp 62-63.

p  ^^15^^ 0. Neugebauer. Vorlesungen iiber Geschichte der antiken mathematischen Wissenschaften (Springer Verlag, Berlin, 1934), pp 101- 102.

p  ^^16^^ J. Wallot. Dimensionen, Einheiten, Massysteme. Handbuch der Physik, Vol. II (Springer Verlag, Berlin, 1926), pp 1-41.

p  ^^17^^ Christoph Sigwart. Logik, Vol. 2 (Mohr, Freiburg, 1893), pp 747- 748.

p  ^^18^^ Hans Reichenbach. Ziele und Wege der physikalischen Erkenntnis. Handbuch der Physik, Vol. IV (Springer Verlag, Berlin, 1929), pp 1-80.

p  ^^19^^ L. I. Mandelstam. Lectures on the Fundamentals of Quantum Mechanics. Polnoye sobranie sochinenii, Vol. V (AN SSSR, Moscow, 1950), p 354.

p  ^^20^^ P. W. Bridgman. Dimensional Analysis (OUP, London, 1931); L. I. Sedov. Melody podobiya i razmernosti v mekhanike (Methods of Similarity and Dimensionality in Mechanics) (Nauka Publishers, Moscow, 1972).

p  ^^21^^ Max Born. Experiment and Theory in Physics (CUP, Cambridge, 1944), pp 38-39.

p  ^^22^^ On systems of units see, for instance, G. D. Burdun. Edinitsy fizicheskikh velichin (Units of Physical Quantities) (Standarty Publishers, Moscow, 1963).

p  ^^23^^ See, for example, L. A. Sena. Edinitsy izmerenii fizicheskikh velichin (Units of Measurement of Physical Quantities) (ONTI, LeningradMoscow, 1948), p 15.

p  ^^24^^ S. P. Kapitsa. The Natural System of Units in Classical Electrodynamics and Electronics. Uspekhi fizicheskikh nauk, 1966, 88, 1: 191.

p  ^^25^^ Of this, in connection with the logic of the relevant issues, see the final section of Chapter X.

p  ^^26^^ G. C. Wick. The Extension of Measurement. Nuovo Cimento, 1966, 4, 2 (Supplement): 319.

p  ^^27^^ Ibid., p 320.

p  ^^28^^ Ibid.

p  ^^28^^ Ibid., p 324.

p  ^^30^^ Ibid., p 325.

p  ^^31^^ Ibid., p 321.

318

p  ^^32^^ On physical processes similar to the translation problem see Leon Brillouin. Scientific Uncertainty and Information (Academic Press, New York & London, 1964), pp 13, 14.

p  ^^33^^ Niels Bohr. Essays 1958-1962 on Atomic Physics and Human Knowledge (N. Y., London, Interscience Publ., 1963), p 7.

p  ^^34^^ A. E. Kovalchuk and Yu. M. Lomsadze. The Essence of Measurement in Quantum Theory. Voprosy filosofii, 1969, 7: 86-87.

p  ^^35^^ Werner Heisenberg. Zur Sprache der Quantentheorie. Physikalische Blatter, 1969, 25, 3: 113.

p  ^^36^^ Studies in the Foundations of Methodology and Philosophy of Science, Vol. II: Quantum Theory and Reality (Springer Verlag, Berlin, 1967); see also L. G. Antipenko. Reality in Quantum Physics. Voprosy filosofii, 1969, 9: 180-182.

p  ^^37^^ In this connection we would like once more to mention A. Lande’s paper Wahrheit und Dichtung in der Quantentheorie in Physikalische Blatter, 1969, 25, 3: 105.

p  ^^38^^ Werner Heisenberg. Op. cit., p 113.

p  ^^39^^ D. I. Blokhintsev. Printsipialnye voprosy kvantovoi mekhaniki (Moscow, 1966); idem. On the Physical Foundations of Quantum Mechanics. Voprosy filosofii, 1969, 3: 127; idem. On the Interaction of a Microsystem and the Measuring Instrument. Uspekhi fizicheskikh nauk, 1968, 95, 1: 75.

p  ^^40^^ D. I. Blokhintsev. On the Interaction of a Microsystem and the Measuring Instrument. Uspekhi fizicheskikh nauk, 1968, 95, 1: 77.

p  ^^41^^ Ibid., p 75.

p  ^^42^^ Ibid., p 88.

p  ^^43^^ Niels Bohr. Op. cit., pp 5-6.

p  ^^44^^ V. A. Fock. Kvantovaya fizika i stroyenie materii, p 10.

p  ^^45^^ Leon Brillouin. Op. cit., pp 102, 104.

p  ^^46^^ Max Born. Statistical Interpretation of Quantum Mechanics. Physics in my Generation (Pergamon Press, London & New York, 1956), p 186.

p  ^^47^^ See, for instance, L. Brillouin. Op. cit., p 32.

p  ^^48^^ G. W. C. Kaye and T. H. Laby. Tables of Physical and Chemical Constants and Some Mathematical Functions (Longmans, Green, and Co., London, N. Y., Toronto, 1959), p 2.

p  ^^48^^ Leon Brillouin. Op. cit., p 32.

p  ^^50^^ Ibid., p 33.

p P^^1^^ On the dialectical requirement of flexibility of concepts, sec
V. I. Lenin. Philosophical Notebooks. Collected Works, Vol. 38,

p p 110. ?^^2^^ L. D. Landau and E. M. Lifshitz. Kvantovaya mekhanika (Quantum
Mechanics) (Fizmatgiz, Moscow, 1963), pp 15-16. ?^^3^^ Niels Bohr. Can Quantum-Mechanical Description of Physical
Reality Be Considered Complete? The Physical Review (Second
Series), 1935, 48, 8: 699. ?^^4^^ Ibid., p 697. 5? Werner Heisenberg. Quantum Theory and Its Interpretation. In: 319 S. Rosental (Ed.). Niels Bohr. His Life and Work as Seen by Ills Friends and Colleagues (North-Holland Publishing Co., Amsterdam 1967), p 107.

p H^^8^^ Albert Einstein. Quanten-Mechanik und Wirklichkeit. Dialectica, 1948, 2, 3/4: 320.

p  ^^67^^ Albert Einstein. Autobiographical Notes. In: P. A. Schilpp (Ed.). Albert Einstein: Philosopher-Scientist (Tudor Publishing Co., New York, 1951).

p  ^^58^^ V. A. Fock. Comments on Albert Einstein’s Creative Autobiography. Uspekhi fizicheskikh nauk, 1956, 59, 1: 116.

p 5^^9^^ Niels Bohr. Atomic Physics and Human Knowledge (John Wiley & Sons, New York, Chapman and Hall, London, 1958), pp 32-66.

p  ^^80^^ Ibid., pp 39-40.

p  ^^61^^ V. A. Fock. Comments on Bohr’s Paper About His Discussions with Einstein. Uspekhi fizicheskikh nauk, 1958, 66, 4: 601.

p  ^^62^^ V. A. Fock. A Critique of Bohr’s Views on Quantum Mechanics. In: I. V. Kuznetsov and M. E. Omelyanovsky (Eds.). Filosofskie voprosy sovremennoi fiziki (Moscow, 1958), pp 67ff.

p  ^^63^^ L. Rosenfeld. Niels Bohr in the Thirties. Consolidation and Extension of the Conception of Complementarity. In: S. Rosental (Ed.). Op. c t., pp 124-125.

 ^^64^^ V. I. Lenin. Materialism and Empirio-criticism. Collected Works, Vol. 14, p 147.