PAUL LANGEVIN—AN OUTSTANDING FRENCH MATERIALIST PHYSICIST

(On the Publication of the Russian Translation of Selected Works)

Yu. Geivish

The Publishing House of Foreign Literature issued at the end of 1949 a Russian translation of the most important general works in the field of physics, as well as articles and speeches on general questions of science, belonging to the pen of Paul Langevin—one of the most outstanding French scientists and a leading public figure and democrat*. If one takes into account that the reactionary government of contemporary Marshallized France, wholly in the service of American imperialism, is trying in every way to belittle Langevin’s scientific and public merits and, according to the testimony of Georges Cogniot, a member of the Central Committee of the French Communist Party and editor of its central organ L’Humanité, is placing every possible obstacle in the way of publishing his writings, then the great ideological and political significance of the fact that Langevin’s most important worldview writings have been issued in a large edition precisely in the Soviet Union becomes clear. This fact once again testifies that only our socialist Motherland—the bulwark of peace and of the anti-imperialist camp—is the true defender of the achievements of the progressive, democratic culture of the working people of all countries.

The figure of P. Langevin is attractive to us in many respects. He is a major physicist, who won worldwide fame and authority through his remarkable works. He is a talented teacher, able to transmit his knowledge to any audience, to kindle in it enthusiasm and a thirst for knowledge. He is a major thinker, striving philosophically to generalize the conclusions of his science on a materialist basis.

* P. Langevin, Selected Works. Articles and Speeches on General Questions of Science. Translated from the French by Z. A. Tseitlina, introductory article by A. A. Maksimov, edited by I. V. Kuznetsov, Publishing House of Foreign Literature, Moscow, 1949.

Langevin was not only a scientist: he was a selfless public and political figure who, under conditions of the class domination of capital, defended the interests of the working masses, an active organizer and activist of the Popular Front of France and of the antifascist movement. In the course of the struggle for materialist science and for democracy, he rose to the worldview of Marxism-Leninism and, toward the end of his life, in September 1944, joined the ranks of the Communist Party of France, which was leading the struggle of the French working people for peace, for genuine democracy, for the freedom, honor, and independence of their homeland.

Throughout his entire life, which began under the conditions of the socio-political situation that had developed in France in the period after the Paris Commune, Langevin experienced an indifferent and cold, and then hostile, attitude toward himself on the part of the bourgeoisie and the ruling circles. Coming from a family imbued with the revolutionary traditions of the Communards, Langevin, only thanks to his extraordinary abilities and exceptional diligence, was able to overcome the enormous difficulties that stood in his way and to become an outstanding professor at the Collège de France, where Langevin worked for 34 years. There he carried out his most important scientific works, which placed him at the head of French physicists. And yet, despite Langevin’s wide renown and scientific authority, official France for a long time did not recognize his scientific merits because of his democratic views and activities directed toward defending the interests of the working people, because of his irreconcilable hostility to reaction. Thus, for example, Langevin was elected a member of the French Academy of Sciences only in 1934, already after many foreign scientific academies—and above all the Academy of Sciences of the USSR—had elected him their honorary member.

The growth of the revolutionary movement of the popular masses of France, especially after the establishment of German fascism in power, increasingly drew Langevin into public activity. In turn, active public activity exerted an enormous influence on the formation of his worldview.

In the 1930s P. Langevin headed the World Antifascist Committee and a number of other advanced democratic organizations and founded the progressive journal, tending toward Marxism, La Pensée (1939). The Hitlerites who occupied France and their French lackeys from Pétain’s circle hated the progressive scientist. Soon after the occupation of France, Langevin was arrested. Freed from prison as a result of a powerful movement of protest by the democratic strata of the population, he was sent into exile in the town of Troyes (Champagne), where he remained almost until the end of the occupation; in May 1944, in view of the threat hanging over Langevin,

arrest as a hostage, his friends from the Resistance movement organized his escape to Switzerland.

Langevin’s social and scientific activity in the last years of his life, in France liberated from the Hitlerites, was expressed chiefly in his leadership of the State Commission for the Reform of Education. The works of this commission are permeated by Langevin’s progressive democratic principles in the field of education, which, of course, cannot be realized under the conditions of capitalist France. In these principles one sees the clear influence of the pedagogical practice of the Soviet Union, the role and significance of which, as the world’s first socialist state, Langevin valued very highly. His sympathy for the USSR found expression also in the fact that in April 1946 he took the post of chairman of the “France—USSR” society.

The death of P. Langevin, which followed on December 19, 1946, evoked a broad response among the French people. His funeral was held at state expense. In October 1948 the ashes of P. Langevin were transferred to the Panthéon. This act on the part of the present reactionary government of France cannot be regarded otherwise than as the result of the powerful pressure of progressive democratic public opinion, which demanded recognition of Langevin’s services to science and to his homeland.

As a physicist, P. Langevin acquired renown at the very beginning of his scientific activity, when, after graduating from the École Normale in 1897, he obtained the opportunity to work in J. J. Thomson’s Cavendish Laboratory, which at the turn of the nineteenth and twentieth centuries was a center for research on electrical phenomena in gases.

In Cambridge Langevin, at first in collaboration with J. Perrin, studied the properties and nature of X-rays, which in that epoch were the object of the close attention of physicists. Langevin’s subsequent work in this period was devoted to another, very important problem—the process of the passage of electric current through gases.

In this field he carried out numerous experimental and theoretical works that played an important role in the development of the theory of the electrical properties of gases.

Langevin’s outstanding works, in which he gave a clear electronic picture of the phenomena of paramagnetism, brought him particular fame as a physicist. These works are now set forth in all physics textbooks and are therefore generally known. Langevin predicted and gave a calculation of the magnetocaloric effect, consisting in the fact that, when the magnetization of a body is suddenly changed, its temperature also changes. In this case it turned out—

...that the amount of heat absorbed by a body upon the sudden cessation of the action of a magnetic field on it increases the lower the initial temperature at which this demagnetization is carried out.

This fact, insignificant at first glance, in reality proved to be an essential circumstance that considerably advanced the technique of obtaining low temperatures. The application of the method of “adiabatic” demagnetization made it possible to obtain the lowest temperature—only a few thousandths of a degree above absolute zero.

At approximately the same time as Einstein, Langevin was working on questions of the special and general theory of relativity. Even before Einstein, Langevin had ideas about the inertia of radiation. Thus the well-known formula of the theory of relativity expressing the interrelation between mass and energy,

\[ E = mc^2, \]

had already been indicated by Langevin on the basis of a calculation of the mass of light from light pressure. True, Langevin’s derivation of this relation, unlike Einstein’s derivation, was not universal in character and was obtained for particular cases; nevertheless, Langevin’s merit lies in the fact that he showed in the simplest way how the inertia of mass follows from classical Newtonian dynamics, while the inertia of radiation follows from relativistic dynamics.

In 1913 Langevin attempted to explain the deviation of the atomic weights of elements from whole numbers by the changes in energy accompanying the formation of complex atoms from the simplest atoms of hydrogen. He gave a new interpretation of Prout’s hypothesis, according to which one should expect for helium an atomic weight equal to four times the weight of the hydrogen atom relative to oxygen, i.e., 4.032. Langevin explained the mass difference of 0.030 between this number and the actual value of the atomic weight of helium, 4.002, by the fact that in the formation of the helium nucleus from four hydrogen nuclei an enormous energy is released, which is carried away together with radiation.

Langevin’s profound penetration into the essence of the theory of relativity was acknowledged by Einstein himself. Thus, according to the testimony of Langevin’s assistant J. Nicollat, “Einstein himself, when speaking of the theory of relativity, always called it the Langevin–Einstein theory.” But especially remarkable are the following words of Einstein himself in an article assessing Langevin’s scientific merits: “It seems to me quite certain that he would have constructed the special theory of relativity if this had not been done elsewhere, so clearly did he understand all the essential points of this theory.”

Langevin, who combined in one person the qualities of an outstanding experimentalist and a profound theorist, also showed himself to be an engi-

...engineer-designer. During the First World War, in 1916, using the phenomenon of piezoelectricity, which at that time had no practical application, Langevin developed a practical method for determining the location of submarines and measuring sea depths by means of ultrasonic oscillations. The ultrasonic echo sounder built by Langevin subsequently came into wide use. Later, during the years of the Second World War, Langevin’s ideas and principles were applied and developed for the construction of more complex devices serving the same purposes (hydrolocators, etc.).

Langevin also proposed a method for determining the intensity of ultrasound by measuring sound pressure. In doing so he makes use of the law establishing the relation between the pressure \((p)\) of radiation and its density and having, as is known, the following form:

\[ p=\frac{U_{em}}{8\pi}. \]

Langevin calls this law the Maxwell–Lebedev law, thereby emphasizing the worldwide significance of Lebedev’s work in the field of light pressure*).

The new branch of physics—ultra-acoustics, to whose development Langevin made a substantial contribution—has advanced significantly over the last 25 years. Work on ultrasound has led to the discovery of many interesting phenomena in physics, physical chemistry, and biology, as well as to a number of major technical applications. Important theoretical and practical investigations of ultrasound have been carried out by Soviet scientists. In particular, the Soviet acoustician S. Ya. Sokolov developed a method of applying ultrasound to detect defects in metals.

P. Langevin’s work on ultrasound is a remarkable illustration of how the unity of theory and practice leads to an invention that not only has primary practical importance, but also stimulates new creative ideas. In this respect Langevin’s creativity is not exhausted by theoretical investigations of ultrasound and their technical applications; Langevin’s investigations in the field of ballistics are also of great importance, having led to results of primary practical significance. In courses on ballistics today one cannot do without the “Langevin formula,” which gives a method for introducing corrections and taking into account the deviations of a projectile from its theoretical trajectory caused by changes in temperature, pressure, etc.

*) Laboratory experiments in the field of ultrasound were carried out for the first time in the world in Moscow under the direction of P. Lebedev. Thus, priority in the study of ultrasonic oscillations belongs to Russian science.

The beginning of the formation of P. Langevin’s scientific and socio-political views belongs to the end of the last century. This was a turbulent period of most fruitful discoveries in physics, called by Lenin “the newest revolution in natural science.” One after another came the discoveries—the electron, Röntgen rays, radioactivity—which marked a turning point in the development of physics. It is known that the idealists hastened to interpret the new stage in the deepening of our knowledge of nature as a refutation of materialism. A section of physicists, bewildered by the idealists, slid into the swamp of Popovism. Langevin waged a struggle against idealism in physics, defending materialist positions on all questions. This is already attested by one of his first generalizing works—the report “The Physics of Electrons” (Selected Works, pp. 60–100), dating from 1904 and devoted to the concept of the electron, new for physics at that time.

For Langevin the electron is an objective reality. In his report he first of all draws attention to the experimental substantiation of the objectivity of the electron’s existence. Calling the latter “the foundation of the newest physics,” he emphasizes that the concept of the electron now rests on “solid experimental and theoretical foundations” (p. 60).

The work by P. Langevin “The Spirit of Scientific Education” (pp. 43–59), dating from 1904, is distinguished by great depth of content. This work is devoted to a critique of the theoretical foundations and practice of teaching physics. At the same time it clearly reveals Langevin’s views on the cognitive significance of science and contains a number of generalizations of a philosophical character. The same problems are also examined in the later work, written in 1926, “The Educational Role of the History of Science” (pp. 310–320).

In the first work Langevin formulates certain general principles underlying natural phenomena—the principle of equivalence and the principle of development of the material objects studied by the physico-chemical sciences, which, according to Langevin, finds its expression in the second law of thermodynamics.

The principle of equivalence establishes the quantitative regularity of qualitative transformations in nature. “It may be asserted,” Langevin writes, “that if some transformation, for example the fall of some heavy body, is accompanied, say, only by the melting of a definite quantity of ice, then it will prove impossible—whatever efforts we may make and whatever mechanisms may be used for this purpose—to combine this same transformation with the melting of another quantity of ice. The reverse transformation must be accompanied by the freezing of the same quantity of water.”

Thus, one can determine the price at which the given transformation is purchased, measure its unchanged value by means of a common measure, for example by means of melted ice, and unambiguously determine the energy lost in the course of this transformation as proportional to the weight of the “melted ice” (pp. 47–48).

Langevin treats the example cited as a special case of a more general principle of the interconnection of quantitative and qualitative changes in nature. “From the very principle of equivalence it follows,” he continues, “that this measurement, independently of the particular phenomenon taken as the common measure, gives us a precise concept of it and of its measure” (p. 48).

Energy is no longer “something that remains constant”; the relative significance of a transformation at the same time gives us a precise concept of it and its measure” (p. 48).

In his remarkable characterization of the significance of the law of conservation and transformation of energy as one of the three great discoveries of the nineteenth century that brought about a radical revolution in natural science, Engels emphasized that it is precisely the establishment of the transformability of energy that constitutes an essentially new addition to the constancy, the conservation of motion, already long since attained. “The quantitative constancy of motion,” wrote Engels, “had already been expressed by Descartes and almost in the same terms as now (by Clausius, Robert Mayer?). But the transformation of the form of motion was discovered only in 1842, and this, not the law of quantitative constancy, is what is new” (Dialectics of Nature, 1948, pp. 226–227).

Langevin, in complete agreement with Engels’ ideas, emphasizes the inadmissibility of interpreting the principle of equivalence one-sidedly, dogmatically, exclusively from the “conservative” side: he shifts the center of attention to the transformation that occurs in a lawful way, with the corresponding equivalents serving as the measure of this transformation.

One cannot fail to see in these anti-metaphysical conclusions of Langevin’s elements of a spontaneously dialectical approach to the interpretation of the laws of conservation of mass, matter, and energy—an approach that found its expression in the rejection of a mechanistic interpretation of these laws.

The second principle—the principle of development—“allows one to assert,” as Langevin writes, “that of two opposite transformations, not accompanied by any external effects, only one is possible: for example, of two phenomena—the mutual diffusion of two gases in their constant common volume and the spontaneous separation of these gases—only the first is possible. In other words, a sufficiently complex system does not pass twice through one and the same state; evolution takes place in a definite order, history does not repeat itself” (p. 48).

In Langevin’s formulation of this principle, his negative attitude toward the mechanical interpretation of development is manifested. Langevin is clearly aware—and he speaks of this more than once in his later addresses—that the discovery of evolution and the development of science itself dealt the strongest blow to metaphysics and mechanism.

Langevin constantly emphasizes the empirical origin of these principles, regarding them as the final result of investigation, and not as something imposed upon nature by consciousness from without. This shows the materialist character of his views on the fundamental question of philosophy: the relation of matter and consciousness. Engels wrote in Anti-Dühring: “Principles are not the starting point of investigation, but its final result; these principles are not applied to nature and human history, but abstracted from them; nature and humanity do not conform to principles, but, on the contrary, principles are correct only insofar as they correspond to nature and history” (F. Engels, Anti-Dühring, 1948, p. 34.—Emphasis ours. Yu. G.). Langevin’s position approaches these propositions of Engels.

In his second work Langevin carries through the idea of development both of objective reality itself and of the human knowledge that reflects it. He criticizes the tendency to absolutize the knowledge obtained at any given historical stage and the unjustified striving to extend this limited knowledge to all fields, both those previously known and those newly discovered.

Langevin notes how, throughout human history, such absolutes (Langevin calls them “mystics”) have replaced and displaced one another: Pythagoreanism, the deductive thinking of the ancient Greeks, scholasticism, induction, mechanism, energetics, and so on. Their common defect is one-sided, metaphysical dogmatism. Against it is directed the fire of Langevin’s criticism.

However, Langevin’s conceptions of the development of knowledge are not free from shortcomings: they are too rectilinear and schematic; they do not take into account the complex interaction and interweaving of views that replace one another, and, most importantly, their social conditioning. Nevertheless, Langevin’s propositions vividly express his striving to show the incompatibility of the living process of cognition with dogmatism, and his resolute anti-idealist position.

The further discoveries in physics that followed in the first quarter of the twentieth century (the creation of the theory of relativity, quantum mechanics, the deepest penetration into the structure of matter thanks to the discovery of new “elementary particles”—the neutron, positron, etc.) provided Langevin with new material for philosophical generalizations. His analysis of the problems of space, time,

of causality connected with the discoveries enumerated above, reveals Langevin’s antidogmatism and anti-mechanicism, his ever more decisive transition from spontaneous materialism to dialectical materialism. This can be traced in a number of works included in the Selected Works.

In the 1911 work “The Evolution of the Concept of Space and Time” (pp. 112–128), which treats these concepts in connection with the theory of relativity, he writes: “The fundamental concepts of space and time, which required revision in the light of the most recent experimental facts, once again attracted the attention of physicists. The empirical origin of these concepts is best and most clearly revealed by the still unfinished process of their progressive adaptation to the ever newer and deeper achievements of human experience” (p. 112).

While noting the empirical character of the origin of the concepts of space and time, Langevin at the same time emphasizes that the metaphysical view of these concepts which had prevailed until recently is inseparably connected with the mechanistic worldview of classical (Langevin calls it “rational”) mechanics, which until recently had attempted to extend its propositions, valid in the domain of the motion of macroscopic bodies, also to the motions of microparticles. “Our concepts of time and space,” Langevin points out, “are concepts required by rational mechanics” (p. 112).

But what was suitable for the mechanical picture of the world proves unsuitable for the electromagnetic picture of the world considered further by Langevin. “A new conception of the world, a new and ever more powerful synthesis,” continues Langevin, “which is the contemporary electromagnetic theory of physical processes, requires a radical revision of the concepts of space and, especially, time known to us from mechanics. All modern methods of experimental investigation also speak in favor of this” (p. 112).

Analyzing the change in the physical concept of space and time caused by the theory of relativity, Langevin at the same time emphasizes the objective reality of space and time. In the article “Time, Space, and Causality in Contemporary Physics” (pp. 129–155) he writes: “The principle of the relativity of space is a confirmation... of the existence of the external reality of space” (p. 133. Emphasis by Langevin.)

The statements cited show that, in his treatment of the highly complex problem of space and time, Langevin was able to give a materialist assessment of the change in views on space and time prepared by the development of experimental physics and connected with the theory of relativity. Langevin understood what constituted

the inadequacy of Newtonian notions of space and time—in their metaphysical character, their separation from matter, their opposition to matter. He also understood the idealist character of the notion of action at a distance, i.e. of the instantaneous (in essence, extra-temporal, since the very form of action at a distance eliminates the concept of time from its expression) propagation of action in infinite space. Therefore he rightly perceived that the theory of relativity, relying on a finite speed of propagation of action and denying Newtonian empty space, arrives at a new understanding of space and time, at an understanding of their inseparable connection with material processes.

The reader of the Selected Works will find a detailed argument for Langevin’s views on these questions in the papers: “The Historical Development of the Principle of Relativity” (pp. 299–309) and “Relativity” (pp. 321–331).

\[ * \quad * \]

Langevin’s rejection of dead, unshakable dogmas is vividly manifested in his consideration of the evolution of the concept of the individual particle. A substantial part of one of Langevin’s most meaningful reports, “Atoms and Corpuscles,” read at the opening of the International Congress on Physical Chemistry at the end of 1933, is devoted to this question. In this work (pp. 332–371) he proves the necessity, in connection with the ever-deepening knowledge of the structure of matter and radiation, of changing the very concept of the individual particle. Penetrating into the realm of intra-atomic phenomena, we encounter difficulties in operating with the concept of the individual particle inherited from the macroworld. Langevin sees the way out of the difficulty in abandoning the notion of the elementary particle as a certain “material point,” since in the microworld this concept is inapplicable.

Langevin attaches great importance to this circumstance: it is precisely with it that he connects the difficulties and contradictions that have arisen along the path of the development of modern physics, upon which “physical” idealists speculate. “Is not the whole contemporary crisis of physics,” he writes elsewhere, “due to the fact that they wished to extrapolate into the intra-atomic domain the concept of the material point from rational mechanics?” (pp. 328–329).

P. Langevin’s views on causality, set forth in the work just mentioned, as well as in the article “Modern Physics and Determinism” (pp. 386–398), written somewhat later, in 1939, attain great philosophical depth. Langevin is an unconditional supporter of determinism, allowing no vacillation or compromises on this question. On the question of determinism he gives decisive battle to idealists of every stripe. He criticizes the erroneous position of Planck, who considers it possible to remove from the “sphere of influence” of causality the socio-

historical processes and the inner world of man. For him, the identification of causality with mechanical determinism, as Planck does, is likewise unacceptable. He sharply protests against the idealistic distortions of the problem of causality in the spirit of Eddington and others like him, who unlawfully try to use modern physics for the struggle against causality as an objective regularity and who disseminate all sorts of anti-scientific mystical fabrications about the dominance of indeterminism and “free will” in nature. He brands their anti-scientific fabrications as “intellectual debauchery” (p. 359).

Langevin believes that the gnoseological cause of the emergence of the anti-scientific theory of indeterminism is that very unlawful transfer, to which we have already referred above, of concepts from one sphere of reality to another. The fundamental error of those who build indeterminism on the relation of uncertainties consists in the fact that they uncritically extend the concept of a particle, inherited from the macroworld, to the sphere of atomic and subatomic phenomena. “If nature,” writes Langevin, “does not give an exact answer to our question concerning the electron, likened to the particle of classical mechanics, would it not be too great a presumption immediately to conclude that nature knows no determinism?

Would it not be more correct to say that the very posing of the question is incorrect and that the electron in general cannot be likened to a particle in the sense of classical mechanics?” (p. 396).

In substantiating the inevitability of the evolution of our concepts, Langevin quite consistently asserts that “undoubtedly, as our knowledge of reality expands, we shall be compelled to modify our idea of determinism as well” (p. 398). But the evolution of our ideas about objective regularity is not its collapse, its disappearance. Only enemies of scientific progress, adherents of reactionary-idealistic philosophy, can, Langevin points out, stand on such a vicious position.

Unconditionally recognizing the objective existence of causality, Langevin at the same time resolutely rejects, as was indicated above, mechanistic Laplacian determinism in application to the microworld. This testifies to Langevin’s recognition of the qualitative specificity of the forms of causal connection for different forms of moving matter. As we see, he rises to a dialectical-materialist treatment of the problem of causality.

For characterizing the development of P. Langevin’s worldview in the direction of dialectical materialism, two of his very last works are of special significance: “Encyclopedia, or the Solidarity of Action and Thought” (pp. 414—421) and “Thought and Action” (pp. 422—437).

In the first work he propagates the idea of creating, in France liberated from Hitlerite domination, a new “Encyclopedia,” regarding the latter as an essential factor in the ideological education of the broad democratic strata of the French people in the spirit of dialectical materialism. A necessary condition of this education is the unity of thought and action, of theory and practice, which he also defends in the second work.

Langevin’s last work, Thought and Action, which appeared six months before his death, is in a certain sense a report in which he definitively sums up his views on the relationship between science and technology, and on the social role of the scientist, whose sacred duty is to defend the interests of the broad laboring masses and to struggle for a democratic peace. Langevin, who spoke out resolutely and boldly against fascism in Germany, France, and other countries, expresses his deep conviction that “...in view of the growing danger of the development of means of destruction, which has threatened humanity for many years, ...peace can and must be established only by the will of the peoples” (p. 436). Langevin’s passionate words against war and in defense of peace resound in our own days from the lips of his followers: F. Joliot-Curie, chairman of the Permanent Committee of the World Peace Congress, J. Bernal, and other progressive scientists at congresses and conferences of supporters of peace in Europe and the USA, directed against the instigators of a new world war.

Constantly emphasizing the inseparable connection between science and the conditions of society’s life, Langevin points out that only dialectical materialism makes it possible fully to grasp the laws governing the development of both the history of society and the history of science, and to foresee the tendency of their further course. He states the fruitful role of dialectical materialism in the process of understanding the history of his own science—physics: “I understood the history of physics well only from the moment,” he says, “when I became acquainted with the basic ideas of dialectical materialism” (p. 420).

Langevin did not remain alone in his struggle against obscurantism and idealism. His views found many supporters among the advanced French scientists of the younger generation, some of whom were his pupils. Among Langevin’s outstanding pupils one must first of all point to the world-renowned scientist Frédéric Joliot-Curie, a member of the French Communist Party, an ardent fighter for peace, who with exemplary courage defends the idea of banning atomic weapons and calls upon scientists to refuse any work connected with the manufacture of atomic bombs; next, one must point to the prominent theoretical physicist Jacques Solomon, a member of the French Communist Party, brutally tortured by the Gestapo in 1942. It should also be noted as ideological followers—

tenders of Langevin, such as the outstanding biologist Marcel Prenant, the philosopher Henri Mougin, the mathematician Gaston Casanova, and others. The philosophical views of these scholars, developed in their works, bear the clear influence of P. Langevin.

*
* *

It would, however, be a mistake to suppose that the evolution of P. Langevin’s views proceeded along an ascending line entirely smoothly, without breaks and inconsistencies. For a critical assessment of Langevin’s scientific and philosophical views in this respect, the introductory article prefixed to the Selected Works is of substantial importance, and especially a number of editorial notes to the text.

The introductory article by A. A. Maksimov provides a fairly exhaustive outline of P. Langevin’s life and an analysis of his scientific-philosophical and socio-political views, which led Langevin to the recognition of dialectical materialism and to his joining the Communist Party of France. In it the reader will also find an indication of a number of Langevin’s erroneous and ambiguous statements that give grounds for their agnostic interpretation. This applies, for example, to the indication of Langevin’s judgment that “the object is the synthesis of all our possible sensations” (p. 8), to his failure to understand the class structure of society, which under the conditions of capitalism he considered “homogeneous” (ibid.), to certain naïve statements of his on questions of historical materialism, in particular on the reasons for the impossibility of wars in the near future (p. 33), and to his incorrect interpretation of dialectical materialism as a synthesis of mechanistic materialism and Hegel’s idealist dialectic (ibid. and following).

The editor of the book, I. V. Kuznetsov, has supplied the text with numerous and valuable notes, in which individual inaccuracies and inconsistencies of the great scientist are noted and corrected.

In particular, the editorial note (p. 373) is justified, criticizing Langevin for the fact that in the article “Fifty Years of the Development of the Science of Electricity” (pp. 372–385) he did not show the contribution of Russian and Soviet scientists to this field of physics. This shortcoming stands out especially sharply, since Langevin in general valued Russian and Soviet science very highly and—according to the testimony of Georges Cogniot—even wrote a work in which he establishes Lomonosov’s priority over Lavoisier in the discovery of the law of conservation of matter and states the profound influence of the great Russian scientist on the development of all subsequent science*).

*) Unfortunately, the whereabouts of this manuscript, as well as of a number of other Langevin manuscripts, is unknown, which is explained by the conditions of persecution of the scientist in occupied France.

The publication of P. Langevin’s Selected Works in Russian will be of undoubted benefit to the Soviet reader, acquainting him with the outstanding scientific work and progressive views of the great French physicist.

Langevin’s views illustrate Lenin’s proposition that under the domination of capital, alongside bourgeois culture, which expresses the interests of the ruling bourgeois classes, there also arises a democratic, socialist culture, as the result of the living conditions of the proletariat. Langevin’s struggle against idealism in physics retains all its relevance at the present moment, when the sharpened class contradictions throughout the world are manifesting themselves ever more sharply in science as well, in the form of a struggle between two ideologies—idealism and materialism. Langevin’s uncompromising materialist line is an example for all progressive foreign scientists seeking a way out of the ideological and political crisis engendered by capitalism.