Chronicle

Elections to the Academy of Sciences of the USSR

At the end of January, elections to the Academy of Sciences of the USSR were completed. Vladimir Aleksandrovich Fock and Petr Leonidovich Kapitza were elected full members of the Academy of Sciences in the physico-mathematical division, the former for his work in theoretical physics and the latter in experimental physics. Two physicists were also elected full members of the Academy of Sciences in the technical division: Nikolai Dmitrievich Papaleksi and Vladimir Pavlovich Linnik, both for their work in applied physics.

Below we present biographies of these scientists.

P. L. Kapitza

Petr Leonidovich Kapitza was born in 1894 in the city of Kronstadt. P. L. received his higher education at the electromechanical faculty of the Petrograd Polytechnic Institute, from which he graduated in 1918. After defending his diploma work on a physical topic, P. L. was retained at the institute as a teacher of physics and mechanics. From 1918 to 1921 he conducted scientific work at the physics department of Leningrad University. Already here P. L. displayed brilliant abilities for experimental work, designing in particular an instrument for detecting and measuring the magnetic moment of the atom. In 1921 P. L. was sent to England, where he was accepted into Rutherford’s Cavendish Laboratory. Here he came to prominence with his work on radioactivity (loss of energy of α-rays in passing through matter, β-rays, scattering of α-particles in a magnetic field). In connection with these problems P. L. began to develop a method for obtaining short-duration (tenths of a second) strong magnetic fields, based on an exceptionally ingenious and original idea. First with the aid of a special type of accumulator battery, and then with the aid of a special generator, he obtained magnetic fields with an intensity above 300,000 gauss (many times greater than had previously been achieved). With this machine, which in its field is an unsurpassed example of modern technology, P. L. carried out a series of classical works on magnetism, which brought him worldwide fame and placed him among the most outstanding physicists. After his work in the field of superstrong magnetic fields, P. L. Kapitza turned to work on the physics of low temperatures. He designed, on the basis of a new principle, a machine for producing liquid helium, which is now used in various low-temperature laboratories.

In 1934 P. L. Kapitza returned to the USSR. At the suggestion of the Council of People’s Commissars, the Academy of Sciences built for P. L. Kapitza, according to his plan and under his most active supervision and direction, a new institute. This institute, in its organization, thoughtfulness, and precision of work, is exemplary not only in the USSR but throughout the world. In a short time P. L. Kapitza, together with his colleagues, carried out at the Institute of Physical Problems a whole series of first-class studies on the viscosity and thermal conductivity of liquid helium, as well as on the Zeeman effect in strong magnetic fields. In 1938 P. L. Kapitza and

...by his collaborators, the construction has been completed of yet another entirely original liquid-air machine with a turboexpander. This machine, of enormous productivity, economy, and simplicity, opens new paths in the technology of refrigeration, oxygen blowing, gasification, and other practical problems. Of particular interest is the theory of turbines and stabilization of turbines, developed by P. L. Kapitsa in connection with the construction of the turboexpander.

P. L. Kapitsa’s works have repeatedly been recognized by the conferral upon him of academic degrees, titles, and awards. He is a doctor of the physical and mathematical sciences and a doctor of philosophy of Cambridge University. In 1929 he was elected a member of the Royal Society of England and a corresponding member of it. An Academician of the Academy of Sciences of the USSR; from 1930 to 1934 he was a professor of the Royal Society and director of the Mond Laboratory in Cambridge. For his early works he received the Maxwell Prize from Cambridge University and the medal of the University of Liège; his most recent work was recognized by the Presidium of the Academy of Sciences of the USSR with the award to P. L. Kapitsa of a major monetary prize.

P. L. Kapitsa is undoubtedly one of the finest experimental physicists of the present day.

V. P. LINNIK

Vladimir Pavlovich Linnik—one of the most outstanding Soviet opticians—was born in 1889 in Kharkov, in a worker’s family. Upon graduating from Kiev University in 1914, he was kept on there as an assistant. From the very first steps of his scientific activity he began to concern himself with the design of optical instruments. Being called up for military service in 1915, during the world imperialist war, he is assigned to the optical factory of the former Main Artillery Administration to study the processes of manufacturing optical instruments, quickly masters the techniques, and himself sets up in Kiev the production of optical instruments of military importance. He continued this work on precision instruments after the Revolution as well, as head of the workshop for precision instruments at the Kiev Polytechnic Institute, and from 1926 he moved to the optotechnical laboratory of the State Optical Institute in Leningrad, where he has developed a large scientific and organizational effort. Devoting himself entirely to the organization of the work of the optotechnical laboratory, V. P. Linnik directs its research along the path of solving tasks continually put forward by the optical industry and, to a considerable extent, of satisfying the demands of the country’s defense. He invented and developed a large number of different methods of laboratory research and testing of optical instruments. Among these are: methods for investigating the aberrations of optical systems; a new method for centering optical systems, which had always required particularly skillful craftsmanship. In this method V. P. Linnik overturned all the customary procedures and rationalized the assembly of the instrument in such a way that all difficulties were transferred from the craftsman to the instrument. The indicated method is so successful that it is now used in assembling all important instruments. The possibility of such centering is based on the double microscope invented by Linnik. With the aid of this microscope one can measure lengths in the vertical direction, examine the contours of an object, irregularities, and scratches with an accuracy up to 3 μ. This instrument was designed at the GOI in 1929, and in 1936 Zeiss issued it under another name. Further, V. P. Linnik designed a microinterferometer—a combination of a microscope and a Michelson interferometer. With its aid one can examine surfaces with an accuracy down to fractions of a wavelength. Zeiss released this instrument without the author’s permission under the mark “Nach Linnik.” Fundamentally new is the method of stereomicrophotography developed by V. P. Linnik, which makes it possible, while taking a photograph, simultaneously to observe successive...

activity of optical sections in depth. No less important are Linnik’s works on increasing the resolving power of instruments by double passage of the rays through the specimen; the ingenious application of the rolling objective in microphotometry; the development of a method of microscopic study of the surfaces of incandescent bodies; and a number of methods for the quantitative determination of the quality of polished surfaces. V. P. Linnik gave a third method for obtaining coherent rays in interferometry (the first two being the Fresnel method and the method of dividing a wave by partial reflection), according to which part of the wave falls on a small aperture and a secondary wave is observed interfering with rays emerging from the small aperture together with the primary rays of the remaining part of the wave—a method whose practical realization requires only a half-silvered plate with a hole.

Alongside his research work V. P. also studies and develops production processes. In the course of all his research activity V. P. Linnik devotes unceasing attention to the introduction of his work into industry. The production processes of optical instruments throughout the country are to a considerable degree established and controlled thanks to the work and energy of V. P. Linnik. In recent years in the USSR, thanks to him, the production of microscopes has been set up and the possibility of their mass production has been created. It is also necessary to note a number of innovations introduced by V. P. Linnik into the technology of manufacturing photographic objectives. Of great value are the control instruments invented by V. P. Linnik for the optical-mechanical industry. V. P. has carried out very important defense-related work on the most responsible military-optical instruments. These works have been introduced into industry and have received full approval.

Alongside his work on optical instruments, V. P. Linnik is credited with a number of highly elegant works in the physics of X-rays. Thus he was the first to realize with X-rays the analogue of Lloyd’s optical interference experiment (interference between the primary beam and a beam reflected from a mirror at grazing incidence); he gave an original method, bearing his name, for studying crystals with the aid of X-rays; and some other works.

N. D. PAPALEKSI

Nikolai Dmitrievich Papaleksi was born in 1880 in the city of Simferopol. He received his higher education at the universities of Berlin (1899–1900) and Strasbourg (1900–1904). In 1904, after defending a dissertation on the topic “Theory and Experimental Study of a Dynamometer for Rapid Oscillations,” he received the degree of Doctor of Physical and Mathematical Sciences of the University of Strasbourg. From 1904 to 1911 he worked at the Physical Institute of the University of Strasbourg as laboratory assistant and assistant to Prof. F. Braun on various scientific and scientific-technical questions from the field of electrical oscillations and their applications to radio engineering.

In 1907 N. D. worked in the laboratory of J. J. Thomson in Cambridge, where he carried out an experimental study of the time of fluorescence. During the period from 1911 to 1914, as a privat-docent of the University of Strasbourg, he gave lecture courses on various subjects and conducted scientific research in the field of electrical oscillations and optics. Returning to Russia in 1914 after the declaration of the imperialist war, N. D. Papaleksi undertook intensive development of radiotelegraphy. He was the first in Russia to develop a vacuum-tube radiotelegraph and to carry out the first experiments (1914) in establishing radiotelegraphic communication between Petersburg and Tsarskoe Selo. On the basis of these experiments the first radiotelegraph station was built in 1916. In the same year, under N. D.’s direction, the first vacuum and electron tubes were manufactured; moreover, in their manufacture

for the first time metal was degassed by means of high-frequency currents. At the same time N. D. develops new types of condensation pumps, applying them in lamp production, and gives a theory of amplifier and generator tubes.

N. D. Papaleksi’s scientific and technical work in the field of electrical oscillations and radiotelegraphy developed especially broadly after the revolution. As scientific consultant to the Trust for the Low-Current Industry, he takes part in various investigations carried out in the Trust’s laboratories; he also works as scientific director in a number of laboratories (TsRL, the scientific radio-engineering department of the Leningrad Electrophysical Institute, and others). At the same time N. D. also conducts extensive pedagogical work as a professor first at the Odessa Polytechnic Institute, and then at the Leningrad Industrial Institute.

From 1934 he takes part in the work of the Physical Institute of the Academy of Sciences as head of the Department of Oscillations. During this time N. D. Papaleksi published, in part jointly with Academician Mandelstam, more than 25 scientific works and obtained more than 40 patents and inventor’s certificates. He carried out a number of major investigations of fundamental importance in the field of oscillations. Many of them found application in practice. The new theory of oscillations developed by him, connected with the theory of differential equations with periodically varying coefficients as applied to nonlinear mechanics, led to the discovery of a new principle of (parametric) self-excitation of alternating currents by means of a periodic change of capacitance and self-inductance. Under N. D.’s direction an inductive parametric alternator of 1.5 kW was built. This same new theory of oscillations made it possible to find an explanation for a whole series of phenomena and to discover new phenomena, very important both for practical and for theoretical physics (regeneration currents, entrainment, asynchronous excitation, the phenomenon of combined resonance). Further, under N. D.’s direction, on the basis of the same theory an autoparametric filter was created for combating atmospheric interference in radio reception, and new schemes for transforming frequency were also implemented.

In the very recent period N. D. Papaleksi developed an ingenious interference method for determining the velocity of propagation of electromagnetic waves. This method made it possible to measure with the greatest accuracy at present the velocity of propagation of a radio wave under actual conditions. This method was made the basis by N. D. of a radio rangefinder, making it possible to measure distances between two remote points. The method was tested in a number of expeditions headed by the author in 1934–1937 and can be applied in navigation, hydrography, etc. For this work and for work in the field of nonlinear oscillations N. D. received (jointly with Academician Mandelstam) in 1936 the first Mendeleev Prize in physics.

In 1931 N. D. was elected a corresponding member of the Academy of Sciences of the USSR.

V. A. FOK

Vladimir Aleksandrovich Fok was born in 1898 in Leningrad. After graduating from Petrograd University in 1922 he was retained as a postgraduate at the chair of theoretical physics. While still a student, in 1919, he began scientific work at the State Optical Institute. Here, in association with a number of major physicists, V. A. Fok received his scientific training as a physicist and, through independent work, acquired a broad erudition in the field of mathematics. V. A. began his pedagogical activity in 1924 at the Leningrad Physico-Mechanical (now Industrial) Institute, and at the present time is a professor at Leningrad University.

V. A. Fok’s works are devoted mainly to quantum mechanics. As early as 1926 he gave a solution of Schrödinger’s equation for very

complex case. In 1927–1928, during a trip abroad, he worked with M. Born in Göttingen and quickly became one of the leading figures in the field of quantum mechanics. In 1929 he gave a generalization of the Dirac equation invariant under the transformations of the general theory of relativity. He then developed two approximate methods for calculating the electron shells of complex atoms. The first method, representing a significant improvement of the Hartree method, is at the present time an indispensable tool for all theoretical physicists engaged in calculating the structure of the electron shell of the atom. In the literature one can find hundreds of papers in which this method is used. The second method is somewhat less accurate, but is distinguished by remarkable elegance. It was V. A. Fock who showed that the degeneracy of the hydrogen levels with respect to the azimuthal quantum number makes it possible to reduce the Schrödinger equation for the hydrogen atom (upon passing to momentum space) to an integral equation for the spherical functions of a four-dimensional sphere. This circumstance greatly simplifies calculations connected with the computation of complex atoms. For his works on quantum electrodynamics and on the theory of the positron, V. A. Fock received the Mendeleev Prize in 1936.

Being a theoretical physicist, V. A. Fock always devoted great attention to problems advanced by the demands of technology and socialist construction. Thus, in a work devoted to the thermal breakdown of dielectrics, Fock, relying on Walter’s experiments and Semenov’s ideas, reduced the quantitative investigation of the phenomenon to a certain system of nonlinear equations and to the question of the existence of stationary solutions of this system. Breakdown occurs at those voltages for which the system ceases to possess a stationary solution. For plane electrodes Fock carried this problem through to the end, and experimental verification fully confirmed his results. In other works V. A. Fock gives a comparatively simple method for determining gas pressure in a gun up to the moment of firing and the pressure at the bottom of the bore after the projectile’s departure—a problem that had been posed already by Lagrange and investigated by Riemann and Hugoniot, but had not been satisfactorily solved. Further, Fock calculates the resistance of a multicore cable for the Air Force, a problem which he solves by reducing it to the question of the conformal mapping of a quadrilateral with zero angles. V. A. Fock’s works on electrical prospecting and well logging, on welding optical glass, on problems in the theory of illumination, and on the theory of elasticity—all have great applied significance. As a characteristic feature of V. A. Fock it should also be noted that in his works he never confines himself to a general solution of a problem, but always brings the solution to its conclusion, often to numerical tables and graphs that can be used directly by the experimental physicist and the engineer.

In 1932 V. A. Fock was elected a corresponding member of the Academy of Sciences of the USSR, and in 1934 he received the degree of Doctor of Physical and Mathematical Sciences without defending a dissertation.