Toward the Thirtieth Anniversary of Soviet Physics

Organization of Soviet Physics

E. V. Shpolsky

I

The thirtieth anniversary of the Great October Socialist Revolution is a significant date in the history of Russian science. Russian science of the prerevolutionary period gave the world many brilliant representatives. The names of M. V. Lomonosov, N. I. Lobachevsky, M. V. Ostrogradsky, D. I. Mendeleev, P. L. Chebyshev, A. M. Butlerov, N. N. Zinin, A. O. and V. O. Kovalevsky, N. E. Zhukovsky, P. N. Lebedev, K. A. Timiryazev, I. P. Pavlov, and many others are pronounced with deep respect in all cultured countries. The Soviet Union, which arose on the ruins of tsarist Russia, not only fully accepted the cultural heritage it received from them, but also significantly augmented it. In this respect the example of physics is perhaps one of the most striking.

The works of individual physicists of prerevolutionary Russia stood at a high level. One can name a number of names that enjoyed wide renown both within and beyond the borders of our country, and a number of works that have firmly entered the body of world science. Such, for example, if we confine ourselves to the nineteenth and the beginning of the twentieth centuries, are the works of E. Kh. Lenz in the field of the theory of electricity (thermal effects of current and the law of electromagnetic induction), the works of Avenarius on the critical state, Stoletov on the photoelectric effect, Lebedev on light pressure, Eikhenvald on the magnetic action of displacement and convection currents, and Golitsyn on seismometry.

This list could easily be expanded by indicating numerous works of very substantial significance and constantly cited in the world literature. Among them are, for example: A. A. Eikhenvald’s work, which first gave a wave interpretation of the phenomena of total internal reflection; the works of D. A. Goldhammer (Kazan) on the theory of the magneto-optical Kerr effect; the work of N. P. Kasterin (Odessa) on the dispersion of sound waves in an artificial medium composed of resonators; the works of A. R. Kolly

E. V. SHPOLSKY

(Moscow—Warsaw) on the dispersion of electromagnetic waves; the work of A. A. Sadovsky (Yuryev), who predicted and calculated the ponderomotive effects, only recently discovered experimentally, in circularly polarized light; the work of O. D. Khvolson on actinometry, and many others.

Alongside these works, widely known also outside Russia, one may name a number of major works and discoveries that have remained little known or entirely unknown. The tragic fate of Lomonosov, who was more than a hundred years ahead of his contemporaries in physics and chemistry and was “discovered” by B. N. Menshutkin only at the beginning of the twentieth century, has already become a trivial example. Many remarkable discoveries and inventions of Russian scientists remained unused, while historical tradition associated these discoveries with other names. It is enough to recall V. Petrov, who discovered the voltaic arc before Davy, and A. S. Popov, who carried out radio telegraphy before Marconi. The outstanding services of P. N. Yablochkov in electrical engineering (he not only introduced the famous “Yablochkov candle,” but was also the first to practice the parallel connection of current receivers, built the first alternating-current dynamo, and made a number of other major inventions), although officially recognized, are recalled far too little.

In 1874 N. A. Umov was the first to advance the concept of the motion of energy and solved, in the most general way, the problem of the motion of energy in liquid and elastic media. However, this work was undeservedly forgotten, and when Poynting, about ten years later, formulated his well-known theorem on the flow of energy in the electromagnetic field, the very concept of energy flow was regarded as fundamentally new. Umov’s priority was recognized much later, already at the beginning of the twentieth century, in the well-known Encyklopädie der mathematischen Wissenschaften.

Finally, one last example should be mentioned. One of the important achievements of experimental physics in recent times is the discovery and wide use of barrier-layer photoelements. However, few people know that the pioneer in this field was Professor V. A. Ulyanin of Kazan University, who in 1888 published a work in which the technology for producing a selenium photoelement with a blocking layer was described in detail, and who carefully investigated its properties.

These examples, whose number could be multiplied, are interesting from various points of view. They show, on the one hand, the high level at which scientific thought stood in pre-revolutionary Russia, the talent of its scientists and inventors. But they also show the absence of a firm foundation, the absence of broad public and governmental support, which placed these scientists in conditions far less favorable than those of their Western European colleagues.

Physics in pre-revolutionary Russia was a science that was purely a university science, in the direct and figurative sense of the word. It developed in the quiet of university laboratories. Indeed, if one sets aside the Main Chamber of Weights and Measures, which had its own purely metrological tasks and solved them at a high level, then before the revolution Russia did not have a single scientific research institute in physics. The Academy of Sciences brought together a few chosen scholars and did not play the role of a major organizing center, at least not in the field of physics. And although a number of important works came out of its physics laboratory (for example, the aforementioned works of Lenz and Golitsyn), this laboratory was always the small personal laboratory of one or another academician, but not a large research institute in the modern sense of the word.

The number of institutions of higher education, in relation to the enormous territory of the country, which stretched from the “cold Finnish rocks to fiery Colchis,” was small. The physicists who worked in these institutions of higher education were, for the most part, solitary scholars. Scientific schools were a rare exception. In this respect, the outstanding merit of P. N. Lebedev is generally known: already at the beginning of the twentieth century he created an extensive scientific school, from which came a number of well-known scientists (Lazarev, Kravets, Arkadiev, Timiryazev, Andreev, and others), and thereby greatly raised the tone of scientific life in Russia, especially in Moscow. Historical justice requires, however, that in this connection another name also be mentioned—one which in recent times has been undeservedly forgotten. This is the name of Professor M. P. Avenarius of Kiev University, to whom belong not only a large number of original works in the field of the study of the critical state, but who, probably for the first time in Russia, in the 1870s and 1880s, created a large school of physicists working in the same field (Nadezhdin, Pavlevskii, Zaionchevskii, and others).

The absence of a suitable environment and of lively communication among scientists, and the political oppression that characterized pre-revolutionary Russia, often led to the fact that a scientist who had brilliantly begun his work in his youth rather quickly abandoned it, limiting himself to obligatory teaching. Others, more active, sought refuge in the West. In the field of physics one may point to Wróblewski, who became famous for his work on the liquefaction of gases. Wróblewski was born in the city of Grodno and studied at Kiev University. Having taken part in underground political activity in his early youth, he soon ended up in prison, after which for five or six years he was in exile and, having regained his freedom, fled abroad, where he obtained the opportunity to work.

The university laboratories in which Russian physicists had to work were still poor and cramped at the end of the nineteenth century. At the beginning of the 1900s, Professors N. A. Umov and D. A. Goldhammer

appealed to the government concerning the necessity of creating physics institutes at the universities. Umov, in particular, in his memorandum on the necessity of constructing a physics institute for Moscow University, referred to the example of little Switzerland, which had spent 2 million francs on the construction of the physics institute of the University of Zurich. In the same memorandum Umov cites the paltry sum of 1,600 rubles per year*) that was allocated at Moscow University for all work in the field of physics, from the acquisition of demonstration apparatus to scientific research. This fact alone shows how unfavorable were the conditions for the development of physics, which, as is known, belongs among the most “expensive” sciences.

Only at the beginning of the twentieth century did specially built physics institutes, modeled on European ones, begin to appear at the major universities (in Petersburg, Moscow, and Odessa). But these institutes had not only (and in most cases not even so much) scientific tasks, but also educational ones. It is enough to recall that in the four-story building of the Physics Institute of Moscow University there was room for P. N. Lebedev’s scientific laboratory only in the basement; almost all the rest of the building was occupied by teaching laboratories and lecture halls.

Meanwhile, the development of physics inexorably required the setting up of physical experiment at an ever higher technical level, and often on such a large scale that it was beyond the capacity of a higher-school laboratory. This fact had long since been recognized abroad. It is enough to recall that the famous Cavendish Laboratory, which was a large and well-equipped scientific-research institute, was created in 1871. P. N. Lebedev, who in 1911 was forced to leave the university as a result of its destruction by the minister of public education, wrote on this subject in the same year: “Large physical laboratories, intended exclusively for scientific research, have long existed in the West—in England, Germany, and America. By steadily working out scientific questions, they, as experience has shown, enrich technology in a quite unexpected way… Unfortunately, we still do not have such a national physical laboratory, although both the need for it and the necessary scholarly forces are present. This is why Russian society should take care to create such a laboratory, after first discussing the size and character of this new institution”**).

However, the tsarist government did not respond in any way to this appeal, and only as a matter of public initiative was the “Moscow Society of the Scientific Institute” created, which, using collected private donations, began organizing in Moscow a research—

*) N. A. Umov, Collected Works, vol. III, p. 146.
**) P. N. Lebedev, Collected Works, pp. 353–354, Moscow, 1913.

...of the physical institute. Unfortunately, P. N. Lebedev did not live to see the realization of his dream, since he died in 1912, a year after leaving the university.

II

From the first days of the revolution, the organization of research work in the USSR was undertaken on a broad scale. While supporting the university scientific centers that had taken shape, and developing with extraordinary intensity a network of higher educational institutions for the training of personnel, the Soviet government at the same time concentrated attention on the development of a network of large research institutes in the most diverse specialties. The creation of a network of research institutes and higher educational institutions after the revolution proceeded at a rapid pace, and by the beginning of the Great Patriotic War, in 1941, the Soviet Union had 750 higher educational institutions and 1170 research institutes. At the same time, the scale of work and the role of the Academy of Sciences changed substantially. From a closed scholarly collegium it was transformed into a powerful association of the largest scientific institutes, called upon to solve not only deeply theoretical questions, but also problems put forward by life. The Academy of Sciences, as the most authoritative scholarly institution in the country, naturally came to coordinate all scientific work. At the same time, alongside the old Academy of Sciences of the USSR, there arose young academies of the national republics—the Azerbaijan, Armenian, Belorussian, Georgian, Kazakh, Latvian, Lithuanian, Uzbek, Ukrainian, and Estonian academies—with their own libraries, museums, and research institutes.

This vigorous development followed wholly from the principle steadily pursued by the Soviet government, according to which research work was made the basis for the industrial development of the country, for the development of its agriculture, public health, and culture. Science was thereby recognized as an indispensable element of state construction. Such a principled formulation of the problem of organizing science, and the very scale of construction of a network of research institutes with tens of thousands of scientific workers of various qualifications, inevitably entailed the necessity of planning research work. In fact, it was necessary not only to ensure the absence of parallelism in the work of institutes similar in their tasks, but also to direct their activity into the channel of satisfying the basic practical needs of the state, while by no means neglecting the most important theoretical problems. This idea of planning scientific work, first advanced by the Soviet government, was entirely new, but now its wise expediency is visible with particular clarity.

For the development of physics, the transfer of all industry onto a scientific basis proved especially fruitful, since, alongside a whole series of the largest physical institutes created in the years of the revolution, an even greater number of scientific-research institutes of a technical character arose. The participation of physicists in the work of these institutes became, of course, absolutely necessary. At the same time, new problems also arose for physics, the source of which was contemporary, profoundly interesting production processes. The problems connected with controlling these processes, based on understanding them and not on the “oral traditions” handed down by experienced craftsmen, proved not only interesting but, in most cases, very difficult. Whereas a researcher of a theoretical bent strives to deal with limiting cases—for example, with negligible concentrations, the absence of interactions, and so on—for production the greatest interest is represented precisely by those conditions which the researcher “of the academic type” tries to avoid.

III

The beginning of the planned creation of scientific institutes for physics dates back to 1918. In that harsh time, at the height of the struggle against counterrevolution and intervention, amid the numerous economic difficulties inherited by the revolution from the First World War and the tsarist government, the largest institutes were created, which quickly raised scientific work in physics to a new, higher level. The pioneers in this historically important undertaking were P. P. Lazarev, A. F. Ioffe, and D. S. Rozhdestvensky. With the support of the People’s Commissariat of Health, in 1918 P. P. Lazarev founded in Moscow the Institute of Physics and Biophysics. In accordance with the diverse interests of its director, this institute carried on extensive work in various fields of physics, geophysics, and biophysics. From within it emerged a number of scholars who subsequently occupied responsible positions in scientific institutions and in departments of higher educational establishments. Such were S. I. Vavilov, A. S. Predvoditelev, G. S. Landsberg, V. V. Shuleikin, S. N. Rzhevkin, P. A. Rebinder, N. T. Fedorov, S. V. Kravkov, P. N. Belikov, B. V. Ilyin, É. V. Shpolsky, and others. At this institute a large number of works were carried out which became widely known. Here one may mention the works in biophysics by P. P. Lazarev himself; further, his own works in geophysics, especially in connection with the study of the Kursk magnetic anomaly; the beginning of V. V. Shuleikin’s work on the physics of the sea; the geophysical works of G. A. Gamburtsev and others. Among works of a purely physical character one should name the works of S. I. Vavilov, as well as those of S. I. Vavilov and V. L. Levshin in the field of fluorescence in solutions, the works of P. A. Rebinder on the influence of surface-active substances on the mechanical properties of solids, and a number of others.

Approximately simultaneously with the Moscow Institute of Physics and Biophysics, two of the largest institutes were founded in Leningrad: the X-ray Radiological Institute and the Optical Institute. The first of these institutes, consisting of three large departments—X-ray physico-technical, X-ray medico-biological, and radium—soon split into three independent institutes, of which the Physico-Technical Institute (already without the prefix “X-ray”) played the greatest role in the development of Soviet physics.

The Physico-Technical Institute was founded by A. F. Ioffe with a group of his pupils—at that time young physicists—whose names are now known far beyond the borders of the Soviet Union. These were P. L. Kapitsa, N. N. Semenov, Ya. I. Frenkel, P. I. Lukirsky, I. V. Obreimov, Ya. G. Dorfman, and others. During its existence the institute created a large and ramified school of Soviet physicists, already numbering five generations, in each of which there are scholars who have gained honorable renown. One may name A. I. Leipunsky, P. S. Tartakovsky, G. V. Kurdyumov, I. K. Kikoin, A. I. Alikhanov, A. I. Alikhanyan, I. V. Kurchatov, A. V. Stepanov, P. P. Kobeko, A. P. Aleksandrov, B. M. Gokhberg, K. D. Sinelnikov, A. K. Walter, B. V. Kurchatov, and others.

The Physico-Technical Institute played an outstanding role in the creation of a whole series of scientific centers in the most important republics and regions of the Union. Thus were created the Ukrainian Physico-Technical Institute in Kharkov, the Physico-Technical Institute in Dnepropetrovsk, the Ural Physico-Technical Institute in Sverdlovsk, and the Siberian Physico-Technical Institute in Tomsk, whose development was in many respects due to the energetic activity of the Tomsk professor V. D. Kuznetsov. To ensure success in organizing all these institutes, the Leningrad Physico-Technical Institute took a heroic measure: it assigned a large number of its leading staff members, who went to these new scientific institutes and there continued and developed their work.

No less important a role in the development of Soviet physics was played by the State Optical Institute. Created by a small group of enthusiasts of scientific and applied optics headed by D. S. Rozhdestvensky, and at the beginning of its existence modest in size, it quickly grew into the largest optical institute in the world, enriching science with many highly important studies, and the national economy and especially the country’s defense technology with valuable practical achievements.

Optical-mechanical production is one of the most delicate and difficult, and, at the same time, one of the most important, especially in relation to the defense of the country. It is well known that in pre-revolutionary Russia this production practically did not exist. The small workshops that did exist were completely ignorant of the essence of the matter, and merely copied foreign ...

models. Optical glass was not manufactured, but was imported from abroad. It took such a powerful means as the First World War of 1914 for the tsarist government finally to see and understand that, with respect to the optical equipment so necessary to it (binoculars, artillery, navigational, and other instruments), the Russian army was wholly dependent on German firms.

The State Optical Institute, created by the revolution, carried out gigantic work that served as a firm foundation for a large Soviet optical-mechanical industry, supplying the Soviet Army with all modern military optical instruments.

IV

The institutes whose activities have been briefly outlined above, as has been said, arose from the very beginning of the revolution. A number of major scientific centers were created in a later period. Among them it is necessary to note the P. N. Lebedev Physical Institute of the Academy of Sciences of the USSR (FIAN) and the Institute of Physical Problems of the Academy of Sciences of the USSR.

The Physical Institute of the Academy of Sciences arose on the basis of the physical laboratory of the Academy of Sciences. As has already been indicated, before the revolution this laboratory was usually the personal laboratory of one academician or another. After the revolution, even before the Academy moved to Moscow, it was expanded; however, the Physical Institute that grew out of it, already in Moscow, so far surpasses the old laboratory in scale that it should be regarded as an entirely new institution. This institute succeeded in assembling major cadres of experimental and theoretical physicists. In the comparatively brief period of its existence (the date of the institute’s founding should be considered 1932), a number of important works were carried out in the institute.

The Institute of Physical Problems (founded in 1935), in the few years of its existence, has succeeded in making a major contribution to world and national science. Built and equipped with rare expediency and scientific comfort, it provides its workers with absolutely every possibility for carrying out physical experiments on a large scale. During the past period, the central work of this Institute has been the investigations of P. L. Kapitsa and his collaborators (A. I. Shalnikov, V. P. Peshkov, and others) in the field of low temperatures, which by their significance belong among the most outstanding achievements of physics in recent years.

The organization of a large network of major research institutes immeasurably expanded the possibilities of Soviet physicists. It goes without saying that their chief attention was drawn to these new centers of scientific thought. However, the old university

centers underwent considerable expansion. Of such university centers, the Physics Institute of Moscow University has played the greatest role over the past 30 years. In the very building of the Physics Institute where, in P. N. Lebedev’s time, only part of the basement was allotted to the scientific laboratory, today the chief place on all floors is occupied by scientific laboratories carrying on intensive work. The result of this work has been a number of major achievements. In this respect it is necessary first of all to note the large number of studies carried out under the intellectual influence and with the direct participation of L. I. Mandelstam, and relating chiefly to two large fields: the theory of oscillations and physical optics.

Among other directions developed at Moscow University, one must first of all point to the work on ferromagnetism (N. S. Akulov, E. I. Kondorskii, and their collaborators). In particular, Akulov’s work on the theory of the ferromagnetic crystal lattice and on the theory of the technical magnetization curve played an important role in the modern development of the doctrine of ferromagnetism and has now entered textbooks. Work in the field of the physics of gas discharge (N. A. Kaptsov, G. V. Spivak, and others), work on X-ray structural analysis (S. T. Konobeevskii), and work in the field of thermophysics (A. S. Predvoditelev) also developed successfully within the walls of Moscow University.

It is also necessary to note the distinctive direction of V. K. Arkad’ev’s work in the field of the doctrine of magnetism and the work, outstanding in its significance, of A. A. Glagoleva-Arkad’eva, who obtained the shortest electromagnetic waves, filling the previously unexplored gap between infrared and microwaves. This result was obtained somewhat differently, independently of A. A. Glagoleva-Arkad’eva, also by M. A. Levitskaia at Voronezh University.

Considerable work was also carried out within the walls of Leningrad University. Here one should point to the studies of P. I. Lukirskii and his pupils on the photoelectric effect, further—the work of E. F. Gross on the scattering of light by elastic standing waves in crystals; a number of works on spectroscopy under the direction of A. N. Terenin were also carried out at the Physics Institute of Leningrad University.

V

Let us now try to outline the principal directions along which Soviet physics developed over the past 30 years. These directions are as follows.

Solid-state physics. The most important results relating to the study of the mechanical properties of solids were obtained by A. F. Ioffe and his extensive school. The widely known works of A. F. Ioffe on strengthening rock salt by dissolving its surface layer with water attracted intense attention.

attention throughout the world. The application of X-ray structural analysis to the study of plastic deformation made it possible for the first time to reveal the mechanism of this phenomenon, so important for all technology.

Among the work of other schools in the field of the mechanical properties of solids, one should point to the numerous works of V. D. Kuznetsov and his collaborators in Tomsk (Siberian Physico-Technical Institute). They developed convenient methods for measuring hardness and other mechanical constants of solids, investigated the plastic deformation of solids, and the physical foundations of metal cutting. The results of all the work on the physics of solids were brought together by V. D. Kuznetsov in the extensive monograph Physics of the Solid State.

P. A. Rebinder (Moscow) discovered the interesting effect of a decrease in the strength of solids under the influence of surface-active substances and indicated practical applications of this effect.

Amorphous state. The work of the school of the Leningrad Physico-Technical Institute—P. P. Kobeko, Kuvshinsky, A. P. Aleksandrov, and others—on the basis of extensive experimental material led to broad generalizations and to a new understanding of the elastic-relaxation properties of high-molecular compounds of the rubber type.

Electrical conductivity of dielectrics and semiconductors. Here, too, substantial achievements belong to A. F. Ioffe and his school. The theory of the thermal breakdown of dielectrics was given by V. A. Fok. The study of the electrical conductivity of electronic semiconductors led to the development of new types of photoelements, rectifiers, and thermoelements.

Let us also note the important work of Soviet theorists (D. I. Blokhintsev, B. I. Davydov, S. I. Pekar, Ya. I. Frenkel) on various questions connected with the theory of semiconductors (the theory of contacts between semiconductors and a metal, or between two semiconductors, the theory of rectifying action, etc.). Kikoin and Noskov recently discovered a new magneto-optical effect, consisting in the fact that, when a plate of a semiconductor placed in a magnetic field parallel to its plane is illuminated, an electromotive force arises. The theory of this effect was given by Ya. I. Frenkel, and later by L. D. Landau.

It is also necessary to note the new work of B. M. Vul on obtaining substances with enormous values of dielectric permittivity (barium titanate).

X-ray structural analysis. The first application of Laue radiographs to the study of the internal mechanism of plastic deformation was made by A. F. Ioffe and M. V. Kirpicheva. The change in the pattern that they observed upon passing through a certain limit (“asterism”) subsequently became the subject of an enormous number of investigations carried out throughout the world. S. T. Konobeevsky and N. E. Uspensky (Moscow) were responsible for the first work on

the application of X-ray analysis to the study of the mechanism of rolling of metals. G. V. Kurdyumov—a representative of the second generation of A. F. Ioffe’s school—organized a large laboratory and created an entire school of physicists engaged in the study of the mechanism of transformations in metallic alloys. It should also be noted the considerable cultural work carried out in this field. Thanks to the development in our country of work in the field of X-ray analysis, factory X-ray laboratories received cadres of trained workers; considerable work was also done in the organization of these laboratories themselves and in propagating their importance in production. Let us also note here an interesting series of works on the X-ray photography of liquids (V. I. Danilov, Dnepropetrovsk).

Low temperatures. In this field two major centers were created: the Institute of Physical Problems in Moscow and the cryogenic laboratory of the Ukrainian Physico-Technical Institute (UFTI) in Kharkov. From the scientific point of view, the works of P. L. Kapitsa devoted to helium II—a remarkable liquid which, in a paradoxical manner, combines superfluidity with superthermal conductivity—are of the greatest significance. This peculiar behavior of helium II was fully clarified by the subtle experiments of P. L. Kapitsa and the theoretical works of L. D. Landau, who constructed the theory of the motion of a quantum liquid. An interesting consequence of Landau’s theory concerning the existence in helium II of a new phenomenon (the so-called “second sound”) received full confirmation in the excellent works of V. P. Peshkov. Among other works we shall note the studies on superconductivity (A. I. Shalnikov), studies of phase transitions and magnetic properties at hydrogen and helium temperatures (UFTI), and studies of absorption spectra at low temperatures (I. V. Obreimov, A. Prikhotko).

Of great importance are the new methods of obtaining low temperatures developed by P. L. Kapitsa. Alongside an entirely original helium machine, he built a turbo-expander machine for liquefying air, which operates at a low initial pressure (4–5 atmospheres instead of the usual 200) and combines remarkable compactness with high productivity. Substantial successes were also achieved in solving the important problem of separating the gases of the atmosphere and, in particular, obtaining oxygen—so necessary for industry—directly from air with a high coefficient of efficiency.

The atomic nucleus and cosmic rays. In this most important new field Soviet physicists have done a great deal of work. The number of investigations carried out in the USSR in the field of nuclear physics is very considerable. We shall note here only the most important. Among them are the works of D. V. Skobeltsyn, in which he succeeded for the first time in observing in a Wilson chamber the paths of cosmic particles. The Wilson-chamber method employed in these works, placed-

charged in a magnetic field, has since become most widespread. A. I. Alikhanov and his collaborators carried out extensive and thorough investigations of continuous β-spectra and pair production; in the course of these investigations the spontaneous emission of positrons by the sources Ra(C+C′) and ThC″ was discovered. The reliability and accuracy of the results obtained in these works in the study of weak effects were to a considerable extent due to the use of Alikhanov’s acute-angle magnetic spectrograph, in which the particles are registered by a pair of Geiger counters connected in a coincidence circuit.

A photographic study of the production of pairs was carried out on a large scale by I. M. Frank and L. V. Groshev.

I. V. Kurchatov and Rusinov were the first to discover the remarkable phenomenon of nuclear isomerism in bromine. A. I. Leipunsky’s laboratory devoted a large number of investigations to the scattering and absorption of neutrons. K. A. Petrzhak and G. N. Flerov, in a delicate experiment, discovered the extraordinarily rare processes of spontaneous fission of uranium.

V. I. Veksler developed an ingenious design for an accelerator (synchrotron) of relativistic particles, i.e. particles possessing such great velocity that their acceleration in a cyclotron is impossible because of the relativistic dependence of mass on velocity. A similar design was proposed by McMillan in the USA, with subsequent recognition of V. I. Veksler’s priority.

It is also necessary to note the intensive and fruitful work of Soviet theoreticians in this field. The hypothesis of the exchange character of nuclear interactions was first formulated independently by I. E. Tamm and D. D. Ivanenko. The theory developed by I. E. Tamm on the basis of this hypothesis, which reduced the nature of nuclear forces to the exchange of light particles (electrons and neutrinos), did, it is true, lead to results quantitatively sharply at variance with experiment; nevertheless, its basic ideas have remained to this day the guiding ones in the further development of the theory of nuclear forces in the works of theoreticians throughout the world.

Important results have been brought by recent investigations of the nature of cosmic rays, carried out in high-mountain expeditions, namely in the expeditions to Mt. Alagez (3200 m above sea level) in Armenia, organized by the Academy of Sciences of the Armenian SSR under the direction of A. I. Alikhanov and A. I. Alikhanian, and in the Pamir expeditions of FIAN, which worked at altitudes up to 4800 m above sea level (V. I. Veksler, D. V. Skobeltsyn).

The most remarkable results of the work of these expeditions are connected with the study of the so-called “narrow atmospheric showers,” consisting of mesons. Further, as a result of the work of the Alagez expedition (Alikhanov, Alikhanian, and Weissenberg), the existence of still another kind of charged elementary particle with a mass in the interval \(400—900\,m\) (\(m\) being the mass of the electron), i.e. par-

particles, differing from all those previously known, including mesotrons with a mass of \(200m\). Investigations of nuclear disintegrations under the action of cosmic rays, carried out in the Pamir expeditions (V. I. Veksler, D. V. Skobel’tsyn), provided convincing evidence in favor of the existence of neutral mesotrons.

The application of the method of thick-layer plates, developed by L. V. Mysovskii and A. P. Zhdanov, enabled A. P. Zhdanov to obtain remarkable photographs of the complete disintegration of atoms into their constituent elementary particles under the action of cosmic rays (the so-called “stars”).

Optics. As has already been mentioned more than once, in the field of optics outstanding successes have been achieved over the past 30 years. The principal centers of optical work were:

a) the State Optical Institute, founded by D. S. Rozhdestvenskii. After D. S. Rozhdestvenskii, the scientific leadership of the GOI belonged to S. I. Vavilov until his election as President of the Academy of Sciences of the USSR.

b) the Physics Institute of Moscow University, where L. I. Mandel’shtam, his closest collaborators G. S. Landsberg and M. A. Leontovich, and their pupils carried out a number of works of first-rate importance.

The work of the GOI in the field of applied optics, outstanding in its significance, began with the development of methods for producing optical glass. Thanks to the efforts of I. V. Grebenshchikov, N. N. Kachalov, and A. A. Lebedev, we now have our own optical glass. The development of methods for polishing glass by the same Grebenshchikov made it possible to manufacture, from our own glass and by our own methods, all kinds of objectives, up to enormous astronomical objectives and the most complex objectives for aerial photography.

In this respect, a major role was played by the creation of a Soviet school of optical calculators (A. I. Tudorovskii, G. G. Slyusarev, and others). The Computing Bureau of the Optical Institute performed calculations for all types of telescopic, photographic, microscopic, and other optical systems. Original calculation methods were created, and auxiliary tables were compiled that facilitated the choice of glass types and the course of the calculation. Ingenious methods of testing optical systems, developed by V. P. Linnik; original designs of optical instruments by the same V. P. Linnik, A. A. Lebedev, E. M. Brumberg, and others; A. A. Gershun’s works on photometry (the theory of the light field) and works on lighting engineering, colorimetry, and scientific photography—all this advanced our applied optics far ahead and rendered invaluable service to our industry and defense.

Alongside the work in applied optics, the same Leningrad school of opticians also produced a number of important works in the field of physical optics. The classical works of D. S. Rozhdestvenskii on anomalous dispersion were continued by his pupils (A. Filip-

...pov and V. K. Prokofiev). In the field of spectroscopy, D. S. Rozhdestvenskii was the first to succeed in deciphering the spectra of the alkali metals. On his initiative, in recent years extensive work has been undertaken on the study of the spectra of the rare earths. Work in the field of atomic spectra (S. E. Frisch), their hyperfine structure (A. N. Terenin, E. F. Gross, and others), molecular spectra (V. M. Chulanovskii), quantitative spectral analysis of minerals and ores (A. N. Filippov and V. K. Prokofiev), and the optical excitation of spectra (A. N. Terenin) has yielded many valuable results; and the new types of spectrographs constructed in the same institute, in which such costly and rare materials as quartz and fluorite are replaced by far cheaper single crystals of chloride and fluoride salts, undoubtedly have a great future. Special mention should be made of the remarkable work of A. N. Terenin, who turned from spectroscopy to the investigation of elementary photochemical processes.

Luminescence in condensed systems (solutions, phosphorescent powders) was subjected to extensive and many-sided investigation in the works of S. I. Vavilov (Institute of Physics and Biophysics, P. N. Lebedev Physical Institute of the Academy of Sciences of the USSR, State Optical Institute) and his collaborators. It may be said that for the majority of the information we now possess concerning fluorescence in solutions, we are indebted to the work of this school. The experimental possibilities here were considerably expanded thanks to the “quenching method” developed by S. I. Vavilov, which makes it possible to carry out quantitative investigations at the limit of the eye’s ability to perceive light. A series of important works by S. I. Vavilov is connected with effects at vanishingly weak illuminations; he discovered and investigated the fluctuations of observed illumination arising from the corpuscular nature of light.

The most important results obtained by the Moscow school of opticians, headed by L. I. Mandelstam, are connected with the study of light scattering. The investigation of molecular scattering by solids, undertaken by G. S. Landsberg, was crowned by the discovery, by G. S. Landsberg and L. I. Mandelstam, of combination scattering. This discovery, made by Moscow physicists quite independently of Raman and simultaneously with him, is undoubtedly one of the most important events in physics of the last 30 years. It gave impetus to many hundreds of works carried out throughout the world; it has been widely used to deepen and broaden considerably our knowledge of the structure of complex molecules, and has formed the basis of analytical methods important in practical applications.

Another new optical effect was discovered within the walls of the Physical Institute of the Academy of Sciences. In particular, it was shown by the theoretical works of Vavilov, Frank, and Tamm that the glow of liquids under the action of hard [[unclear: continuation cut off at page bottom]]

…of hard $\gamma$-rays constitutes a completely distinctive kind of radiation: the radiation of an electron moving uniformly with a velocity greater than the phase velocity of light in the given medium. The repetition of Cherenkov’s experiments on a large scale, carried out in America, fully confirmed all his results.

Of great practical importance was the development of methods for the quantitative spectral analysis of metals, begun under the direction of G. S. Landsberg at the Physics Institute of Moscow University and continued under his direction at the Physics Institute of the Academy of Sciences.

The photoelectric effect and the properties of photocells also served as the subject of numerous works. Thanks to the high-precision spherical-condenser method introduced by P. I. Lukirsky (Physics Institute of Leningrad University), it proved possible to verify Einstein’s equation in the most impeccable manner and to obtain the most accurate value of Planck’s constant. The properties of complex photocathodes were investigated by the Moscow group of physicists (P. V. Timofeev and his collaborators), who worked at the All-Union Electrotechnical Institute (VEI), and by a group of workers of the Physics Institute of the Ukrainian Academy of Sciences in Kiev (N. D. Morgulis and his collaborators). In this same institute, the technology for producing, and the properties were studied of, silver sulfide photocells excellent in their qualities, possessing, like the sulfur-thallium photocells of A. F. Ioffe, high integral sensitivity and sensitivity in the near infrared part of the spectrum. The antimony-cesium photocathode was studied, put into production, and widely used in the USSR from 1937 onward—earlier and more fully than in the USA (Lukirsky, Luneva, Lukyanov, Morgulis, Khlebnikov). L. A. Kubetsky was the first to build an electron multiplier based on secondary electron emission. Finally, P. S. Tartakovsky (SPTI—the Siberian Physico-Technical Institute in Tomsk) investigated the photoelectric effect in crystals, and T. P. Kravets and M. V. Savostyanova (GOI) established the nature of the so-called “latent image” in photographic layers.

A very important question, from the point of view of developing new light sources—the luminescence of a gas discharge—was investigated at the All-Union Electrotechnical Institute (V. A. Fabrikant and his collaborators).

The physics of oscillations belongs to the number of fields that were developed by Soviet scientists especially intensively and with especially great success. The exceptional credit for the development of these most important questions, both in theoretical and in practical respects, belongs to the schools of L. I. Mandelstam and N. D. Papaleksi and to the joint work of L. I. Mandelstam and N. D. Papaleksi. Through these works, first, a whole new field was created—the physics of nonlinear oscillations, which is attracting ever greater atten…

tion. The extensive school of physicists engaged in the development of these problems already has several generations. Work begun at the Physics Institute of Moscow University is being continued at the P. N. Lebedev Physics Institute of the Academy of Sciences, at Gorky University (A. A. Andronov, S. E. Khaikin, G. S. Gorelik, and others), and in a number of research institutes of an applied character. Another series of important works, belonging already to recent years, takes its origin from the work of L. I. Mandelstam and N. D. Papaleksi on the velocity of propagation of electromagnetic waves in the radio-engineering range. Strange as it may seem, until quite recently there existed no unimpeachable definitions of this velocity. L. I. Mandelstam and N. D. Papaleksi developed an ingenious interference method, which was applied for direct measurements in a number of expeditions. These works found valuable practical application in the development of radio-interference methods for measuring distances. The instrument built on this principle—the radio range-finder—has already found extensive applications in hydrography, navigation, etc.

Theoretical physics. Soviet theoreticians took the most active part in solving the most important problems of theoretical physics, which over the past 30 years has undergone extraordinarily rapid development. It is impossible either to enumerate all the works published in this field or to name all the names. We shall confine ourselves to only a few examples. V. A. Fock is the author of a number of important works in the field of quantum mechanics, quantum electrodynamics, and the general theory of relativity. He developed two approximate methods for solving the Schrödinger equation for a system of particles, one of which gives significantly more accurate results than the method earlier proposed by Hartree, while the other is distinguished by unusual simplicity and elegance and, with somewhat less accuracy, makes it possible to obtain the result quickly. These methods are now used by theoreticians throughout the world.

The prematurely deceased outstanding Soviet theoretician A. A. Friedmann was the first to find a nonstationary solution of Einstein’s gravitation equation. This work of Friedmann laid the foundation for an entire direction in relativistic cosmology.

Ya. I. Frenkel is the author of a very large number of works in the most diverse branches of theoretical physics. He put forward a number of ideas that proved extraordinarily fruitful. Thus, he was the first to give a wave-mechanical theory of the electrical resistance of metals; he was also the first to suggest the idea of the origin of ferromagnetism due to quantum-mechanical “exchange forces.” The distinction introduced by Ya. I. Frenkel between electronic and “hole” conductivity in semiconductors proved fruitful to the highest degree.

The currently generally accepted idea of the proton-neutron structure of the nucleus (in place of the old idea of elec-

... neutron-proton structure, which led to irresolvable contradictions) was first formulated by D. D. Ivanenko.

I. E. Tamm, in addition to the already mentioned works on the theory of nuclear forces, is the author of a number of important works on the quantum optics of metals. The existence of surface energy levels in crystals, established by him, is now generally recognized.

Of very great importance were the works of L. D. Landau on the theory of the so-called phase transitions of the second kind, on the diamagnetism of a gas of free electrons, and on the quantum theory of collisions. Recently, as already mentioned, L. D. Landau has successfully developed the theory of the motion of a quantum liquid, which made it possible not only to explain the remarkable properties of helium II discovered by P. L. Kapitsa, but also to predict a new effect—the existence in helium II, alongside ordinary sound waves (pressure waves), of special temperature waves (the so-called second sound). The experimental confirmation of this theory by V. P. Peshkov’s experiments has already been mentioned above.

A major step in the theory of ferromagnetism was made thanks to the work of N. S. Akulov and his collaborators. Akulov discovered a regularity, which he called the “law of anisotropy,” that made it possible to calculate the basic physical properties of ferromagnetic crystals.

Chemical physics. In developing this new field, lying on the boundary between physics and chemistry, Soviet physicists took the most active part. The physicist N. N. Semenov developed the chain theory of chemical reactions, which is the natural result of applying modern ideas about the structure of molecules and the mechanism of energy exchange to elementary chemical processes. This theory has had a great influence on work in the field of chemical kinetics in recent years, and the experimental material obtained by N. N. Semenov and his collaborators on the mechanism of combustion and explosive reactions, and on various kinds of oxidation reactions, is of great value from both the theoretical and the practical points of view.

An outstanding role in the remarkable successes achieved by photochemistry over the last two decades was played by the work of the Soviet physicist A. N. Terenin, who was the first to succeed in unraveling the mechanism of the optical dissociation of molecules and, in recent years, has advanced far in the study of the photochemistry of complex molecules, using for this purpose the most refined physical methods.

Finally, to the physicist V. N. Kondrat’ev, photochemistry and chemical kinetics owe the investigation of the important phenomenon of “induced predissociation,” the study of the mechanism of the decomposition of simple molecules under the action of electron impact, the investigation of chemiluminescence in gases, the development of the most delicate optical methods for detecting chemical radicals, and so on.

Since this entire vast area is more closely connected with chemistry, we shall confine ourselves to the brief remarks given above.

Biological physics. This borderline field was also intensively developed by Soviet physicists, especially by P. P. Lazarev and his school. P. P. Lazarev developed a coherent physicochemical theory of nervous excitation and tested it on extensive and varied experimental material. This also includes the work carried out at the P. P. Lazarev Institute by N. T. Fedorov and S. V. Kravkov on physiological optics, the work of P. N. Belikov and S. N. Rzhevkin on physiological acoustics, and the work of S. N. Rzhevkin on irritation by electric current.

The work of V. V. Shuleikin belongs to an entirely different range of problems in biological physics. This range of problems was aptly named by him the biological physics of the sea. V. V. Shuleikin studied the mechanics of motion of an individual fish and of a school of fish, the aerodynamics of the flight of flying fish, and the physical nature of camouflage (mimicry) in fish.

VI

In parallel with the growth of the network of scientific-research institutes and the increase in the number of workers in the field of physics, the demands placed on scientific literature naturally also grew. Before the Revolution, Russian scientific literature on physics was extraordinarily poor. For serious study one inevitably had to use almost exclusively literature in foreign languages. As an exception one may mention O. D. Khvolson’s five-volume Course of Physics, which played a major role in raising the level of culture in the field of physics in Russia and was translated into several foreign languages. The periodical press was also poorly represented. Research papers were published in the physics section of the Journal of the Russian Physico-Chemical Society at St. Petersburg University. Undoubtedly, the second part of this journal, which bore the special title Problems of Physics and consisted of review articles, played a positive role; a positive role was also played by the nonperiodical collections New Ideas in Physics, published under the editorship of I. I. Borgman.

From the very beginning of the Revolution, the publication of scientific literature was placed on an entirely different, immeasurably broader scale. As a result, over 30 years—especially over the second half of this period—the literature on physics has become so extensive that not only for special university courses, but also for candidate examinations, it is possible to indicate serious monographs in Russian on almost all questions. Among them one should mention A. F. Ioffe’s Physics of Crystals, A. A. Andronov and S. E. Khaikin’s Theory of Oscillations, D. V. Skobeltsyn’s Cosmic Rays,

“The Quantum Theory of Molecules” by K. V. Nikolsky, “Quantum Mechanics” by V. A. Fock, the two-volume “Electrodynamics” by Ya. I. Frenkel and his “Quantum Mechanics” and “Kinetic Theory of Liquids.” Some of these monographs (the books by Ioffe and Frenkel) have also appeared in translations into foreign languages. A number of original textbooks have also appeared. Such are “Molecular Physics” by A. F. Ioffe, “Mechanics” by S. E. Khaikin, “Optics” by G. S. Landsberg, “Theory of Electricity” by I. E. Tamm, “Statistical Physics,” “Field Theory,” and “Mechanics of Continuous Media” by Landau and Lifshitz, “Statistical Physics” by M. A. Leontovich, “Quantum Mechanics” by D. I. Blokhintsev, “Atomic Physics” by E. V. Shpolsky, “Kinetic Theory of Matter” by A. K. Timiryazev, and a number of others. Finally, one cannot fail to note the excellent editions of the classics of physics. We now have in Russian Newton’s “Principia,” “Opticks,” and “Lectures on Optics,” the first in A. N. Krylov’s translation, and the optical works in translations by S. I. Vavilov; further, Galileo’s “Dialogues,” Mayer and Helmholtz’s “Law of Conservation of Energy,” Lagrange’s “Analytical Mechanics,” and a number of other classic works.

The periodical literature is represented by four journals. Of these, three publish original research (“Journal of Experimental and Theoretical Physics,” “Journal of Technical Physics,” and “Proceedings of the Academy of Sciences of the USSR, Physical Series”); the fourth is the review journal “Advances in Physical Sciences.” The five-volume “Physical Dictionary,” published under the editorship of P. N. Belyakov, and the nine-volume “Handbook of Physical and Technological Constants,” published by the Technical Encyclopedia, are valuable reference works on all questions of physics.

Congresses and conferences before the revolution were a rare phenomenon in Russia. They were held in the form of “Congresses of Russian Natural Scientists and Physicians,” which included a physics section. In principle these congresses were supposed to meet annually. In reality, however, they were convened very rarely. Shortly before the war of 1914, more specialized “Mendeleev Congresses on Physics and Chemistry” began to be convened, but they too were a rare phenomenon. After the revolution, the scientific and public life of physicists experienced a considerable revival. As early as 1919, the “First Congress of Russian Physicists” met in Leningrad. In subsequent years such congresses met almost annually. However, the number of reports quickly grew, to such an extent that serious discussion of them proved impossible. In view of this, in recent years it has been found more expedient to convene conferences on individual questions. Such conferences, mainly in the form of sessions of the Physico-Mathematical Division of the Academy of Sciences, are held several times a year.

Here we conclude our brief outline of the development of Soviet physics. A little over a hundred years ago, in his review “Russian Literature in 1842,” V. G. Belinsky wrote: “Science among us is still too tender and weak a plant, which has not yet had time even to put down roots, let alone burst into luxuriant and fragrant bloom. This, however, does not mean that we have no science: it means only that science in Rus’ is still something like the Eleusinian mysteries—an exclusive possession of a small chosen class of people, and not of society as a whole…” These vivid words, written at the beginning of 1843, could in a certain sense be applied to the entire prerevolutionary period in the history of Russian science: science in tsarist Russia, although it grew considerably stronger in the second half of the nineteenth century and in the first decade of the twentieth, still remained the affair of a few chosen individuals. All the more grandiose, therefore, is the shift that our science underwent during the years of the revolution.

In the days when the significant date of the thirtieth anniversary of this world-historic event is approaching, after the severe trials of the Great Patriotic War, which ended with the complete rout of the most vicious enemy of culture and progress—German fascism—it is instructive to look back at the path traversed by Soviet science. This period is characterized precisely by the fact that science among us ceased to be “something like the Eleusinian mysteries” and became the possession of the entire people. Paraphrasing the splendid words of D. I. Mendeleev, we may say: truly, the scientific sowing has sprouted for a people’s harvest! And when we recall the luxuriant flowering and rapid advance that Soviet science has experienced in just one special field of physics, our hearts are filled with enormous joy, pride in our beautiful motherland, and calm confidence in its great future.