LEON IOSIFOVICH KORDYSH

On June 11, 1932, Leon Iosifovich Kordysh died at the age of 54; he was professor of theoretical physics at the Kiev Physico-Chemico-Mathematical Institute and head of the theoretical department of the Scientific Research Institute of Physics.

L. I. Kordysh was, in the words of O. D. Khvolson, “one of the most talented specialists in theoretical physics that we have.” His numerous scientific works—more than 60—were devoted to the study of the most diverse questions of physics: mechanics, acoustics, spectroscopy, thermodynamics, the theory of X-rays, photoelectricity, the theory of electrical conductivity,

superconductivity, the theory of relativity, the theory of the structure of the atom, quantum theory, quantum mechanics, radioactivity. In all these questions the works of L. I. Kordysh always stand at the level of the contemporary achievements of science. In each work he displays great erudition, a perfect command of the methods of mathematics, mechanics, and theoretical physics. Quickly mastering each new problem, L. I. Kordysh expressed his distinctive point of view and introduced new achievements into science.

Some of L. I. Kordysh’s first works are devoted to the theory of secondary oscillations, by which he understood both overtones and combination tones. Subjecting the theories then existing (1908) to criticism, L. I. substantiated an original theory of secondary oscillations, which are physically determined by the nature of material resonators; he generalized this theory to electromagnetic oscillations and predicted the existence of combination light oscillations. At approximately the same time L. I. published the paper “Band Spectra,” in which he expressed the idea that band spectra owe their origin to molecules, whereas line spectra are produced by atoms.

L. I. applies the general theory of oscillations to the investigation of dispersion both in the large work “Dispersion of White Light” and in other articles; he attempts to give a more direct and concrete explanation of the phenomena of dispersion than that of Drude and Lorentz, proceeding from the viewpoint of an unspecified composition of the light flux.

The Zeeman phenomenon attracted much of L. I.’s attention; to it he devoted an extensive monograph* and a number of articles. As early as 1915, without making use of Bohr’s theory, which was then little known, he derived a number of relations that subsequently became part of the quantum theory of the atom. He returned to them in later works of 1924 and 1925 and applied them to the explanation of the polarization of components.

A number of L. I. Kordysh’s works are devoted to the theory of relativity. Already in 1910 his article on the theory of relativity appeared—one of the first articles in the Russian language—in which he gives a very elegant elementary derivation of the Lorentz–Einstein formulas. In 1917, when the general theory of relativity was still little known here because of wartime conditions, L. I. gave a distinctive exposition of this theory in the work “Gravitation and Inertia,” and then applied it to the explanation of diffraction phenomena (“The Gravitational Theory of Diffraction Phenomena”). In the work of 1923 he examines the question of the existence of gravitational fields in intramolecular space.

L. I. deals with the theory of X-rays in several articles. In the work of 1923 he gives a theory of continuous X-ray—

* “Anomalous Zeeman Phenomena,” p. 170, 1915.

... spectrum and derives a relationship between the wavelength of the most intense rays and the magnitude of the potential, analogous to Wien’s law for light.

In the same year he publishes a study of electromagnetic waves with velocities greater than the speed of light.

In a number of works L. I. deals with the theory of electrical conductivity and superconductivity. L. I. considers the phenomenon of conductivity from the point of view of a certain stationary electromagnetic process, which consists of a series of successive processes of ionization and recombination of the atoms of a conductor. L. I. Kordysh regards the cause of ohmic resistance as the binding of free electrons by positive ions, and derives the dependence of conductivity and self-induction on the probability of such binding of ions, which, in turn, depends on temperature. Superconductivity occurs when this probability becomes equal to zero, and the conditions of motion of free electrons approach the conditions of motion of a jet of ideal gas.

L. I.’s last works are devoted to quantum mechanics—to the relation between the quantum conditions of Sommerfeld and Bohr, to the connection between wave theory and matrix theory, and to a visual representation of the wave function, which he regards as a certain periodic analyzer of the coordinate field in which the motion of a material point takes place.

In this brief note we have by no means exhausted the varied content of L. I.’s works. A characteristic feature of them is the constant striving—behind complex theoretical constructions—to preserve a clear picture of the physical phenomenon. “In the theoretical construction of schemes of physical phenomena,” he says in his dissertation, “we wished, in addition to the formal mathematical schematization of the observational data (mathematical theories), also to illustrate the phenomena by pictures of the processes taking place (physical theories).” This striving to concretize theory, to make it as clear as possible, determines the entire direction of L. I. Kordysh’s work.

Especially significant was the role of L. I.’s scientific activity in Ukraine, where for a long time he was almost the only representative of theoretical physics. For many years, one may say, he planted in Ukraine this branch of science and aroused interest in its fundamental questions.

L. I.’s pedagogical activity proceeded, with the exception of a three-year interruption, entirely in his native Kiev, where he was born (in 1878), and completed his higher education (the physico-mathematical faculty of Kiev University in 1901). For the work submitted to the physico-mathematical faculty under the title “A Geometrical Investigation of the Acceleration of Points of a Solid Body,” he was left as a scholarship holder to prepare for a professorship. In the same year, 1901, he was invited to head the laboratory ...

LEON IOSIFOVICH KORDYSH

classes in physics with students of the Kiev Polytechnic Institute. In 1904 he was sent by the Kiev Polytechnic Institute to the University of Berlin, where he worked in the Institute of Theoretical Physics under Prof. Planck and in the physics laboratory under Prof. Warburg. In 1907 he was elected a staff instructor of the Kiev Polytechnic Institute. In 1908 he passed the master’s examination in physics. In 1909 he was elected privat-docent of Kiev University and of the Higher Women’s Courses, where he taught experimental physics, certain sections of theoretical physics, and directed physics laboratories. In 1909 he was sent to Paris, where he worked at the Sorbonne under Poincaré and Appell in the laboratories of Bouty and Pellat. In 1910 he was elected professor at the Women’s Medical Institute, where he organized a physics room and practical classes in physics and conducted the teaching of physics. In 1911 he was elected professor of the Geographical Institute. In 1913–1914 he was sent abroad to study radiotechnical work. During this assignment he became acquainted with the stations and installations of wireless telegraphy in Nauen, Darmstadt, and Munich, and with the organization of laboratory practical work on weak currents and electrical oscillations. In addition, he worked in Munich in the Institute of Theoretical Physics under Prof. Sommerfeld and in the Polytechnic Institute under Prof. Wien, in his laboratory of electrical oscillations. At the same time he assisted Prof. Koch, who was giving a special course in X-ray physics, in setting up lecture demonstrations. In 1916 he defended his dissertation on the topic “Anomalous Zeeman Phenomena.” In 1917 he was elected professor of Kiev University and of the Higher Women’s Courses, where he taught courses in theoretical and experimental physics. In 1918 he was sent by the council of Kiev University to Crimea to organize the teaching of physics in the branch department of Kiev University in Crimea. In 1921 he was elected professor of the Kiev Polytechnic Institute in the department of theoretical electrical engineering. In the same year he was elected professor of theoretical physics at the Kiev Institute of Public Education (the former university), in place of the late Professor Kosonogov, and there he worked until the end of his life. In 1923 he was invited to the Kiev Roentgen Institute to organize and direct the roentgenophysics laboratory. In the same year he was invited by the Ukrmet to organize a laboratory for studying the radioactive properties of the soils and rocks of Ukraine. In 1924 he was invited to the research chair of electrical engineering to direct the department of theoretical electrical engineering. In 1925 he was invited to the research chair of physics to direct the section of theoretical physics. After the reorganization of the chair into the Scientific Research Institute of Physics, he was confirmed as head of the Theoretical Department of the institute, where, until the end of his life, he carried on active work as a scientific-re-

... both of an investigative character and in the training of postgraduate personnel. In 1926 L. I. was elected a corresponding member of the All-Ukrainian Academy of Sciences and a member of the Krakow Academy of Sciences.

Throughout his entire life, and especially in his later years, L. I. devoted much attention and energy to public and organizational work. As already mentioned, he took a significant part in organizing scientific institutions and laboratories; he organized the X-ray physics laboratory of the Kiev X-ray Institute, the radioactive laboratory of Ukrmet, the radio-engineering laboratory of the Kiev Polytechnic Institute, the physics laboratory of the Crimean University, and took part in organizing the physics laboratories of the Kiev Polytechnic Institute, the Higher Women’s Courses, the Women’s Medical Institute, and others. Beginning in 1923, L. I. regularly conducted seminars on various problems of theoretical physics at VINO and the Physico-Chemical-Mathematical Institute. These seminars took place outside L. I.’s regular working hours. At them he selected candidates for postgraduate study. From among the participants in these seminars there has already emerged a number of researchers occupying a prominent place among Soviet physicists. In general, L. I. devoted an extraordinary amount of effort and attention to the training of Soviet physicists. L. I. also took an active part in the work of professional and public organizations.

Special mention must be made of his work in publishing a number of courses that he had delivered over a number of years (the theoretical foundations of electrical engineering, radio engineering, theoretical physics).

Working selflessly, L. I. died at his post of labor. On the day of his death he was still working in the morning on preparing a book for publication. His sudden death prematurely cut short the intense activity of L. I., who had by no means yet exhausted all his capacities. But what he did accomplish is sufficient to secure for him the grateful memory of Soviet physicists, and especially of his colleagues and pupils, who will never forget their talented teacher.

L. Shtrum.

LIST OF WORKS BY L. I. KORDYSH

1. Geometrical investigation of the acceleration of points of a rigid body. (“Kiev Univ. Izv.,” 1900, about 80 pp.).
2. Regularities in spectra. “Fiz. Obozr.,” 1905.
3. Thermodynamic investigation of band spectra. “Zhurn. Rus. Fiz.-Khim. O-va,” 1906.
4. Regularities in band spectra. “ZhRFKhO,” 1906.
5. Secondary oscillations. “ZhRFKhO,” 1908.
6. On the theory of secondary oscillation. “ZhRFKhO,” 1908.
7. Decomposition of the energy of elastic oscillations. Publ. Kiev Polytechnical Institute, 1909.
8. On the theory of white light. “ZhRFKhO,” 1909.
9. On the question of the formation of secondary oscillations. Publ. Kiev Polytechnical Institute, 1909.
10. An elementary derivation of the basic formulas of the theory of relativity. Publ. Kiev Polytechnical Institute, 1910.
11. Sur la formation des vibrations secondaires, “Bul. de la Soc. Frans. de Physique,” 1911.
12. Experimental investigation of bodies with surface coloration in connection with Kundt’s law. “Prot. Kiev Phys.-Chem. Soc.,” 1900 (also in Phys. Zeitschr., 1910).
13. On the dispersion of white light, “Kiev Univ. Izv.,” 1911.
14. Sur la théorie de l’effet photoélectrique, “Le Radium,” 1912.
15. On the speed of group waves, “Prot. Fiz.-Khim. O-va,” 1912.
16. Displacement of thermodynamic equilibrium, “Prot. Kiev Phys.-Math. Soc.,” 1911.
17. Motion of energy in media possessing scattering capacity. “Kiev Univ. Izv.,” 1911 (also in the volume in honor of T. K. Suslov).
18. Basic laws of the electromagnetic field, 1913.
19. Derivation of the second fundamental law of the electromagnetic field, “Izv. Kiev Polytechnical Institute,” 1914.
20. On the theory of physical dimensions, “Izv. Kiev Polytechnical Institute,” 1915.
21. Quasi-elastic force, “Izv. Kiev Polytechnical Institute,” 1915.
22. Anomalous phenomena of Zeeman, Publ. 11, Kiev, 1915, 230 pp.
23. Zur Theorie d. Lorentz’schen Resonators, “Annalen d. Physik,” 1915.
24. Penetrability and intensity of X-rays, “Izv. Kiev Roentgen Committee,” 1915.
25. On the wave nature of X-rays, “Fiz. Obozr.,” 1916.
26. Coolidge X-ray tubes, “Izv. Kiev Roentgen Committee,” 1916.
27. Residual X-rays, “Izv. Kiev Roentgen Committee,” 1916.
28. On the question of the origin of characteristic X-rays, “Kiev Univ. Izv.,” 1916.
29. General theory of relativity, Course of theory (manuscript), 1917.
30. Gravitational theory of diffraction phenomena, “Kiev Univ. Izv.,” 1917.
31. Inertia and gravitation, “Kiev Univ. Izv.,” 1918.