Awarding of the Stalin Prizes in Physics for 1951

In the Resolution of the Council of Ministers of the USSR published on March 13, 1952, on the awarding of Stalin Prizes for outstanding works in the field of science, invention, literature, and art for 1951, a large number of persons worthy of the high title of laureate of the Stalin Prize for works in physics and related sciences were named.

The first-degree prize was awarded posthumously to Academician Sergei Ivanovich Vavilov for the scientific work The Microstructure of Light and the popular-science book The Eye and the Sun, published in its fifth edition.

S. I. Vavilov’s monograph solves the problem of substantiating an independent section of physical optics, for which S. I. Vavilov was the first to introduce the term “microstructure of light.”

It embraces the works of S. I. Vavilov and his collaborators from one very general point of view. They are considered only insofar as they constitute a component part of “micro-optics.” This includes: fluctuations of the luminous flux, the interference properties of very small emitters, manifestations of the duration of excited states of molecules, and the interaction of luminous molecules with the surrounding medium.

The formulation, developed in this book, of the problem of the microstructure of light in a number of cases illuminates the significance of S. I. Vavilov’s earlier investigations in a completely new way.

The first part of the book is devoted to the widely known experimental studies of quantum fluctuations of light by the visual method. In this field S. I. Vavilov was a pioneer, who for the first time proved the existence of this phenomenon. In the book these studies are examined for the first time with such completeness. The interpretation of the results goes far beyond the framework of S. I. Vavilov’s original works, in which this phenomenon was established.

The second part of the book is devoted to questions of the interference of light. It contains a profound examination of the problem of the interference of light “as a method and as a principle.” The question of the superposition of light, which lies at the basis of the physical teaching on interference and of the applicability of the so-called Bouguer law, is treated in the early works of S. I. Vavilov considered in the book. These works have now become an integral part of the entire general treatment of the problem of the interference of light.

The subsequent sections of this part of the book are devoted to the theory of the interference of light and to the use of this phenomenon for studying the nature of elementary emitters, i.e. to the method proposed and developed by S. I. Vavilov. Finally, one of the 16 paragraphs of this part of the book is devoted to the phenomenon of Cherenkov, which is considered only as “an example of the application of the interference method in optics,” i.e. only to the extent required by the aims of the book.

The third part of the book is entitled “Properties of Light Emitted by an Absorbing Medium.” This section includes works that were developed especially intensively by S. I. Vavilov in the last years of his life. These include studies of the absorption of light in thin layers, which are a direct continuation of the work on the laws of light absorption (considered in the second part of the book), and which unite into a single whole a number of other phenomena—including the notion of induced resonance, which S. I. Vavilov made the basis for explaining concentrated quenching and depolarization of luminescence. Work in this field is presented in the concluding part of the book*).

S. I. Vavilov’s popular-science book The Eye and the Sun appeared in 1950 in its fifth edition.

The main idea of the book—the profound connection between the properties of sunlight and the features of the human eye—is revealed in its introduction. From the original, naïve notions of light, the Sun, and vision, the author leads the reader to the heights of modern science, which has disclosed many astonishing properties of light and its effects on the eye. “The eye cannot be understood without knowing the Sun,” writes the author in the concluding lines of the book.

In the first chapter, “Light,” the author gives a brief exposition of the basic ideas about the nature of light, as well as an outline of the historical development of optics from the time of Newton and Lomonosov to our own day. Here S. I. Vavilov appears equally as a physicist, a philosopher, and a historian of science.

The following chapter of the book, on the Sun, is extraordinarily rich in content. Here the reader is introduced to a wide range of phenomena connected with questions of astronomy, astrophysics, geophysics, and the theory of light emission. All this is presented briefly and, at the same time, engagingly and simply. The concluding part of the chapter is devoted to the question of the energy of solar radiation. It again returns the reader to the basic ideas about light and matter and to Lebedev’s experiments on light pressure, in connection with the relation between energy and mass.

The last chapter of the book, “The Eye,” reveals to the reader the remarkable purposiveness of the structure of the eye, which arose in the course of the development of living organisms. Using a number of examples of the structure of the eye in various organisms, the author shows the individual stages in the development of the visual apparatus and its adaptation to the external environment. The author devotes his main attention to the features of the human eye. They are discussed in the book in a many-sided, substantial, and interesting way.

The book’s many illustrations are also of interest. The dispersion of light by a prism is illustrated by a drawing by Academician Kraft, depicting an apparatus from the Kunstkamera of the Petersburg Academy of Sciences (first half of the eighteenth century). This drawing is reproduced both in the text and on the cover of the book. The diffraction of light is explained by the well-known photographs of V. K. Arkadiev. The process of the conversion of light into matter is illustrated by a photograph of a “pair” electron-positron, obtained by L. V. Groshev and I. M. Frank**).

The works of Corresponding Member of the Academy of Sciences of the USSR Nikolai Vasil’evich Belov, awarded the Stalin Prize, First Class, may be united under the general title “Research in the Field of the Atomic Structure of Minerals.”

N. V. Belov’s work on structural crystallography became widely known after the completion of the systematic work he had conducted over a number of years on the creation of a theory of the densest

) A detailed review of S. I. Vavilov’s book The Microstructure of Light was published in UFN*, vol. XLIV, p. 117 (1951).

) A detailed review of S. I. Vavilov’s book The Eye and the Sun is printed in the present issue of UFN.

of spherical packings and applying it to the description and analysis of the structures of minerals, ionic crystals, and metallic phases.

N. V. Belov showed that, although an infinite variety of types of closest spherical packings is possible, with a stratification varying from two, in the simplest case, to infinity, the number of Fedorov symmetry groups is strictly limited and equal to eight.

The ideas laid down in Belov’s theory of closest and dense packings have been used for various branches of Soviet structural crystallography and crystal chemistry.

One result of the theory of closest and dense packings is the explanation of the preferential formation of certain space groups in the crystallization of definite types of compounds. This selectivity ultimately has a thermodynamic basis, consisting in the fact that, out of the countless multitude of possible configurations of a system, under given thermodynamic conditions the state of equilibrium corresponds to the single configuration with the smallest free energy. Crystals are an equilibrium form of existence of a solid with a minimum of free energy. For many classes of crystalline compounds, the thermodynamic principle of the minimum of free energy can, with sufficient approximation, be expressed in geometric language as the principle of minimum occupied volume. Such compounds will naturally crystallize in those few space groups that make possible a dense packing of the structural elements of the crystal and that follow from the theory of dense packing.

The second practical value of the theory of dense packing lies in the fact that this theory led to the creation of powerful methods for deciphering complex crystalline structures.

The effectiveness of these methods was proved in a series of investigations carried out by N. V. Belov with a group of collaborators on the deciphering of the complex structures of minerals: ramsayite, diopside, chalcocite, tourmaline, milarite, ilvaite, and others. The results of N. V. Belov and his students in determining the structure of complex minerals in a number of cases proved unattainable for Japanese and some American investigators.

A considerable group of N. V. Belov’s works is devoted to the development of the theory and to the elaboration of computational methods of X-ray structural analysis. The main attention was given to the central problem—the direct methods of X-ray analysis. All the works in this field are characterized by the simplicity of the ideas contained in them and, thanks to this, by the great practicality and vitality of the proposed computational techniques. Almost all structural laboratories carry out summation of multiple Fourier series of interatomic vectors and of the electron-density function by the system of “strips” developed and introduced by N. V. Belov and V. P. Butuzov. In many laboratories accelerated methods are used for calculating structural amplitudes by N. V. Belov’s nomograms.

Soviet structural crystallography and crystal chemistry, developing the advanced ideas of Lomonosov, Mendeleev, and Fedorov, were created over the last 10–15 years. An enormous role in the creation in our country of this field of research, important for science and the national economy, belongs to N. V. Belov.

N. V. Belov’s works on the methodology of X-ray structural analysis are widely used in the petrographic laboratories of the country; works on structural mineralogy are widely known to geologists, petrographers, and mineralogists. N. V. Belov’s investigations of mineral structures rank among the best achievements of the Soviet structural school and in a number of cases surpass foreign investigations.

The Stalin Prize, Second Class, was awarded to scientific workers of the P. N. Lebedev Physical Institute of the Academy of Sciences of the USSR—Vadim Leonidovich Levshin, Vsevolod Vasilievich Antonov-Romanovsky, Zinaida Lazarevna Morgenshtern, and Zinaida Alekseevna Trapeznikova—for investigations of new luminescent compounds and the development of the theory of their action.

Professor of Odessa State University Elpidifor Anempodistovich Kirillov was awarded the Stalin Prize for the discovery and investigation of the fine structure of the absorption spectrum of photochemically colored silver halide, set forth in a series of articles published in the journals Izvestiya Akademii nauk SSSR, Uspekhi nauchnoi fotografii, and in the Proceedings of Odessa State University named after I. I. Mechnikov in 1949–1951.

E. A. Kirillov, over many years engaged in the study of electronic processes in real crystals, approached the great and important problem of the nature and mechanism of formation of the latent photographic image.

In the article “Absorption Centers of Coloration and of the Latent Image in Silver Halide,” printed in the collection Uspekhi nauchnoi fotografii, vol. I, 1951, the author summarizes the results of the work of his collaborators on the fine structure, discovered by him, of the absorption spectrum of photochemical coloration in silver halide. Even the first results of the investigations led to the conclusion that the absorption bands constituting the fine structure must belong to centers formed by silver in the form of particles containing a small number of atoms, weakly bound to the crystalline structure and located predominantly on the surface of the crystals.

To verify the correctness of such a conception of the nature of the centers connected with the fine structure, the experiments described in the article were undertaken with thin polycrystalline layers of silver chloride and silver bromide, colored by condensation on their surface of vapors of metallic silver evaporated in vacuum. The results of measurements of the absorption spectrum of such “additively” colored layers showed that their spectrum is characterized by the same fine structure, with the same maxima, as the spectrum of silver halide colored photochemically. Thus an independent confirmation was obtained of the author’s assumptions concerning the nature of the centers connected with the fine structure.

On the other hand, if the conception of the centers of the fine structure as particles containing only a small number of silver atoms is correct, then it may be expected that these centers are capable of being destroyed under the action of light of a wavelength lying in the region of their absorption. Spectral measurements carried out by two methods showed that the action of light of corresponding wavelengths actually destroys the centers of the fine structure, the maximum effect being produced by wavelengths coinciding with the absorption maxima of the centers.

According to views now accepted, the destruction of a center consisting of several silver atoms must begin with excitation or detachment of an electron, with its possible transition into the conduction band of the crystal and, consequently, may be accompanied by an internal photoeffect. Indeed, the investigations set forth in the second article, “Photoeffect and Centers of Photochemical Coloration in Silver Halide,” placed in the Collection of Physico-Mathematical Faculty and Scientific-Research Institute of Physics, vol. III, included in the Proceedings of Odessa State University named after I. I. Mechnikov, vol. XIII (69), 1951, led to the result that the maxima of the fine structure, if not all of them, then to a considerable extent, are simultaneously also maxima

...photoconductivity. The spectral investigation of the internal photoeffect in silver halide salts, carried out in this work with great care, taking into account not the incident energy, as is usually done, but the absorbed energy, showed the possibility of simultaneous detection on one and the same spectral curve of almost all the maxima that had previously been obtained separately by different observers. This result provides a new illumination of the question of the spectral distribution of the photoeffect in silver halide and of the centers associated with it.

In the third article, “On the Question of Absorption Centers in Photochemically Colored Silver Halide,” published in 1950 in volume XIV of Izvestiya of the Academy of Sciences of the USSR (physics series), and representing a brief account of a report at the Conference on Spectroscopy in Sverdlovsk, certain considerations are set forth with the aim of somewhat clarifying the ideas concerning the nature of the centers of fine structure that had taken shape on the basis of the works described above. This clarification may apparently be achieved by establishing an analogy between the results of the author and his collaborators, on the one hand, and optical (Smakula) and electronographic (König) investigations of thin metallic layers, on the other. Comparison of the results of these investigations leads to the probable supposition that the centers of fine structure, if they consist of several atoms, are elementary silver crystallites that do not yet individually possess the properties of a normal metal.

The centers with which the fine structure of the absorption spectrum of colored silver halide, discovered and investigated by the author, is associated may also be observed under conditions of a latent image.

The results obtained lead to the conclusion that the absorption spectrum of silver halide, measured after exposure sufficient to form only a latent image, does not differ substantially, in the positions of the maxima, from those previously investigated. Thus, the fine structure reveals a new direct path toward the investigation of the latent image, which is a fundamental problem in the theory of the photographic process. On the other hand, new possibilities also arise in the study of the structure of thin metallic layers and of elementary particles of metal, which apparently play a substantial role in these layers.

For investigations in the field of meteoritics, the Stalin Prize was awarded to the Scientific Secretary of the Committee on Meteorites of the Academy of Sciences of the USSR, Evgenii Leonidovich Krinov.

His works are set forth in the books Meteorites, The Tunguska Meteorite, and in the article “The Form and Surface Structure of the Crusts of Melting of Individual Specimens of the Sikhote-Alin Iron Meteorite Shower.”

E. L. Krinov took an active part in expeditions to study the largest meteorites—the Tunguska and the Sikhote-Alin. He provided new conclusions concerning the flight trajectory of the Tunguska meteorite. In studying the Sikhote-Alin meteorite, which fell in 1947, the author discovered on the surface of a number of fragments of the meteorite solidified splashes of molten metal, which had formed when sharp edges were melted during the flight of the meteorite.

The book Meteorites is the first compilation of modern data on meteorites. In its introductory part, the history of the development of meteoritics—a new branch of science, which first arose in Russia a decade earlier than in Western Europe—is set forth. The role of our compatriots, scholars, and the broad masses of the people in the development of meteoritics is shown. For the first time a terminology used in meteoritics is given. Further, in the corresponding chapters of the book, the conditions of falls ...

meteorites falling to the earth, and data on the composition, structure, and physical properties of meteorites. A separate chapter gives the morphology of meteorites, introduced by the author for the first time as a special branch of meteoritics. The book also contains descriptions of the circumstances of the falls of many remarkable meteorites that fell in Russia and the USSR. The last chapter gives a summary and sets forth a contemporary working hypothesis on the origin of meteorites. At the end there is appended a list of the principal literature on meteorites, comprising 161 titles.

The prize was awarded to Professor of Leningrad State University named after A. A. Zhdanov, Viktor Nikolaevich Tsvetkov, for studies of the structure and properties of high-molecular substances, set forth in a series of articles published in the journals: Doklady Akademii nauk SSSR, Zhurnal eksperimental'noi i teoreticheskoi fiziki, Zhurnal fizicheskoi khimii, and Kolloidnyi zhurnal in 1949–1951.

One of the most important tasks in the field of the study of high-molecular substances is the determination of the size and shape of their molecules. The first part of the problem is satisfactorily solved by the use of the ultracentrifuge or of simpler, though less accurate, methods. The situation is considerably worse with the determination of the configuration of chain molecules, which is determined by their flexibility, branching, and the intramolecular interaction between the various polar groups of the chain molecule. At the same time, determining the shape of a polymer molecule, as well as the reasons that give rise to one configuration or another, is necessary for establishing the connections between the structure of the polymer and its mechanical properties. It is enough to point out that a long and very flexible chain molecule of linear structure may be coiled into a ball and have the same shape as a highly branched molecule, although the mechanical properties of these polymers will differ sharply. In particular, determining branching is very important for characterizing synthetic rubbers.

The difficulties in determining the structure of chain molecules are connected with the necessity of studying very dilute solutions. In a series of works by V. N. Tsvetkov, a number of new experimental approaches to the study of such solutions were given. Among them, first of all, one should mention the investigation of the double refraction of light in flowing solutions of polymers, in which the possibility was shown of quantitatively separating the photoelastic effect, associated with deformation of the molecules themselves in the jet, from the effect of particle shape. Thus a method was developed that makes it possible to estimate the flexibility of chains in solutions. Connected with these works is a series of works on the dynamo-optical effect in liquids and the study of their relaxation properties, which, of course, do not have a direct bearing on polymers.

The second, most essential result is the new method developed by V. N. Tsvetkov for studying the diffusion of polymers in a solution with the aid of Lebedev’s polarization interferometer. In this way V. N. Tsvetkov obtained the possibility of measuring the rate of diffusion at concentration differences of 0.02–0.03%, and in his very first work on the study of the concentration dependence of the diffusion coefficient he succeeded in establishing a very distinctive effect of an increase in the rate of diffusion with increasing concentration of the solution. The possibility of reliably determining the value of the diffusion coefficient in very dilute solutions, in which interaction between polymer molecules is in fact excluded, is a substantial expansion of the experimental possibilities for the study of polymers.

The prize was awarded to Corresponding Member of the Academy of Sciences of the Georgian SSR Elepter Luarsabovich Andronikashvili for experi-

mental investigations of the properties of helium-II, set forth in articles published in the Journal of Experimental and Theoretical Physics in 1946–1949.

Soviet physicists possess very complete and successful investigations of the properties of liquid helium in the region of temperatures from 2.19° abs. and below, i.e., in the region where helium passes into the superfluid state and becomes a “quantum liquid.”

A significant contribution to the development of this field of physics was made by E. L. Andronikashvili with his works.

A very substantial point in considering the properties of helium-II is the ratio of the densities of its superfluid and normal components and the dependence of this ratio on temperature. E. L. Andronikashvili directly discovered and studied these components.

It followed from the properties of helium-II that, when a stack of closely spaced disks oscillates in helium, the fraction of helium entrained by the disks will be strongly dependent on temperature. The reason for this lies in the fact that superfluid helium, when flowing along a wall, does not interact with it. Only that part of the helium which possesses normal viscosity, rapidly decreasing with decreasing temperature, interacts with the wall.

The works of E. L. Andronikashvili are devoted to the experimental verification of these considerations, which follow from L. D. Landau’s theory. By measurements of the period of slow torsional oscillations of a vessel suspended on an elastic thread and filled with helium-II, it was shown that the moment of inertia of the vessel–liquid system changes significantly as the temperature is lowered in the interval \(\lambda\)-point — 1.0 K. Hence it follows that not all the liquid is entrained into the motion of the vessel, but only some part of it possessing the property of viscosity.

Thus it was shown that in helium the simultaneous existence of two independent types of motion is possible—normal and superfluid.

Also very important are Andronikashvili’s works devoted to viscosity. Before his works, the viscosity of helium-II had essentially not been measured, and experimentalists used incorrect data. Andronikashvili’s experiments led to substantial progress in this important question.

The Stalin Prize was awarded to the staff members of the Crimean Astrophysical Observatory of the Academy of Sciences of the USSR, Prof. Andrei Borisovich Severny and Evald Rudolfovich Mustel, for investigations of chromospheric flares on the Sun.

The authors discovered a new phenomenon of changes in the intensity of wing lines, lagging behind the development of the intensity in the center of the line, and gave a theory of this phenomenon. The depth of occurrence of a flare in the chromosphere was determined. Of still greater interest is the detailed investigation of the enormous flare of 5/VIII 1949. In this flare, which flared up for 10 minutes and died down for 50 minutes, it was possible to obtain 17 spectrograms and to trace the change of its spectrum.

The width of the hydrogen line \(\mathrm{H}_2\) in this flare reached the enormous value of 15 Å. The authors gave a theory of the contours of the lines of this flare, determined by natural damping and the Stark effect, which quite naturally explains the observed spectroscopic phenomena. A similar effect of natural damping in radiation is observed for the first time.

The authors were further able, from the observations obtained and the theory, to determine the ionization conditions, temperatures, and densities in flares and to estimate confidently the intensity of \(L_\alpha\) and \(L_\beta\) radiation. These calculations for the first time numerically explain the observed changes in the ionization of the \(D\) and \(E\) layers.

atmosphere and the associated Dellinger effect—the disruption of radio communications.

The Stalin Prize was awarded to scientific staff members of the Institute of Chemistry of Silicates of the USSR Academy of Sciences: Georgii Anatol'evich Smolenskii, Nikita Aleksandrovich Toropov, and Anatolii Isidorovich Borisenko for their investigations of the physical and chemical properties of ferroelectrics and ferrites, set forth in a series of articles published in the journals Doklady Akademii nauk SSSR, Zhurnal tekhnicheskoi fiziki, and Zhurnal prikladnoi khimii in 1949–1951.

Over a number of years the authors carried out extensive and very serious investigations of ceramic-type ferroelectrics. Ferroelectric properties were first discovered in lead, cadmium, and strontium titanates and in lead zirconate. On the basis of a generalization of the experimental material, the conditions for the appearance of spontaneous polarization in crystals were established and the substances in which ferroelectric properties may appear at certain temperatures were indicated. Later work by other researchers confirms the regularities established. From the temperature dependence of the coefficient of thermal expansion it was found that ferroelectrics can have both positive and negative volume spontaneous electrostriction.

A valuable scientific discovery was made in the investigation of solid solutions of \( \mathrm{BaTiO_3—BZ_2O_3} \) and \( \mathrm{BaTiO_3—BaSnO_3} \). In a number of these solid solutions, ferroelectrics with “zero” electrostriction were discovered, distinguished by an extremely low dependence of dielectric permittivity on the field strength. For the first time in ceramic-type dielectrics, such a high value of dielectric permittivity was obtained (30,000 and more). It was indicated that analogous regularities should be observed in all solid solutions whose components are ferroelectrics with different signs of electrostriction. The experimental data obtained the correct theoretical explanation in the authors’ works. Investigations of solid solutions of ferroelectrics made it possible to establish the possibility of increasing the stability of the dielectric permittivity \(\varepsilon\) and of the piezomodulus \(d\), and of increasing the ratio

\[ \frac{d}{\varepsilon} \]

(which is important for a number of applications) as compared with barium titanate.

Another group of oxides investigated by the authors are ferrites. They created a new group of magnetic nonmetallic highly permeable materials for communications engineering and other purposes. The authors showed that in any series of mixed ferrites of cubic structure, representing solid solutions of a ferromagnetic and an antiferromagnetic, there must be compositions with zero anisotropy constant and magnetostriction and, consequently, with a high value of initial magnetic permeability. The authors arrived at this independently of analogous investigations in Holland and America.

Academician Il'ia Vasil'evich Grebenshchikov, together with a group of coworkers, was awarded the Prize of the Second Degree for work in the field of instrument building.

Professor Dmitrii Ivanovich Blokhintsev was awarded the Stalin Prize of the First Degree for the textbook Fundamentals of Quantum Mechanics, published in a second revised edition in 1949.

The textbook sets forth the foundations of the new quantum mechanics and its mathematical apparatus. The greatest merit of the textbook is that it is the first textbook on quantum mechanics in which the exposition is conducted consistently materialistically. Much space is devoted to metho-

logical questions. A critique is given of idealistic distortions in quantum mechanics on the question of causality, the understanding of the wave function, the uncertainty relation, and others.

The book gives a sharp, scientifically argued critique of the principle of complementarity, which Western scientists are unlawfully attempting to establish as the foundation of quantum mechanics. In the book, a consistently conducted conception is presented of the wave function as an objective characteristic of the state of a particle, characterized by the particle’s belonging to one ensemble or another, in opposition to the subjective understanding of the state proposed by foreign scientists.

V. Shepel