The soul, who left to the rest,
But on the Earth, you stranger,
Your songs will wander be."
Coll. "Muza in the temple
of science", M., 1982.
ESSAY OF SCIENTIFIC ACTIVITY
DMITRII IVANOVICH BLOKHINTSEV
(11.01.1908 -- 27.01.1979)
B.M. Barbashov, A.V. Efremov, V.N. Pervushin
There is a good tradition in our country to name the streets of cities after their famous citizens. Among them are Blokhintsev streets in Russian little towns of Dubna and Obninsk, named in honor of the outstanding Soviet physicist, distinguished organizer of science, a colleague of Kurchatov in creation, formation and development of nuclear science, technology and nuclear power engineering in our country and countries of East Europe. "The name of Dmitrii Ivanovich Blokhintsev ranks row with the names of Sechenov, Timiryazev, Umov, Lebedev, Vernadsky, Vavilov, Khokhlov and many others, who make the pride of our nation" ("Pravda", 23 January, 1980). Dmitrii Blokhintsev enriched the world's science by fundamental works in solid state and statistical physics, acoustics, physics of reactors and atomic power engineering, quantum mechanics, quantum field theory and quantum electrodynamics, high-energy and nuclear physics, philosophy and methodology of science. His role in education of physicists and engineers in our and East Europe countries is widely known and received the deserved acknowledgement. He was lucky enough to be the founder of many directions in science but first of all he was the personality - phenomenally versatile and many-sided person, scientist, engineer, inventor, teacher, artist, poet, state and public figure, the contact with whom was a great pleasure. Strong influence on the outlook of Dmitrii Ivanovich was made by the acquaintance with the works by K.E. Tsiolkovski and personal correspondence with him. DI perceived from Tsiolkovskiy that spirit of the Russian science of the beginning of the XXth century, which was not just aspiration to achievement of specific scientific results, but rather the creation of integral harmonic world outlook. Admiration of beauty and harmony of the world, and also the highest degree of respect to Nature and Man was inherent in the mentality of Tsiolkovskiy. Just for this reason - loved to stress DI - Tsiolkovskiy never used such word combinations as "conquest" of Space, but he always spoke about its "exploration". Blokhintsev succeeded in preserving these youthful ideals of the world perception till the end of his life. This tendency toward the truth of his initial period, ever increasing with the years, forced him not only to be up to date in all basic scientific achievements in both physics and other fields of knowledge, mathematics, philosophy, biology, economy, etc. but also to develop his own original viewpoints and judgments. Dmitrii Ivanovich believed that it was rather easy to learn by solving already formulated problems in any fashionable field of contemporary physics. Almost any person with a sufficiently regulated mind can become a not bad theoretician. More difficult is to pose problems by himself. Physicists whose interests are determined by their own outlook are considerably less numerous, but just they most frequently become the authors of those "fashionable" directions in science which give food and work to minds of many others. The famous experiments of Rutherford in splitting an atom forced young Dmitrii Blokhintsev, a graduate of Moscow industrial-economical technical school, to focus his attention on those enviable possibilities which nuclear energy promises and this determined his further way. In 1926 he entered the Physics Department of Moscow State University (MSU), where distinguished scientists as L.I. Mandel'shtam, S.I. Vavilov, N.I. Luzin, D.F. Egorov, and I.E. Tamm were his teachers. There were the years of quantum mechanics formation and of explanation with its aid of many mysterious physical phenomena. DI's early works were already noted by large skill and depth of physical thought. For his graduate work he was recognized worthy of the Doctor of Sciences degree (1934). DI calculated the work function of electrons from the metal and based on it offered an explanation of the anomalous magnetic properties of bivalence metals. This was the reason that energy of electron in these metals depended not only on the absolute value of its momentum but also on its direction with respect to the crystal axes. He generalized Bloch's theory to the case of overlapping zones. His formula for the energy of the overlapping zones was of special importance. At the same time, DI opened a nonlinear dependence of the radiated light (in Stark effect) on the intensity of the falling one (1933). This work was the first study on the nonlinear optics, which is now being developed substantially. During the subsequent years he gave the first explanation of the mechanism of the mysterious phosphorescence phenomenon. The basic idea of this work wonderfully illustrates figurativeness of thinking of the scientist. He noted that the presence of local impurities in phosphorouses led to the appearance of local levels between the lower zone and the conduction band. Therefore, the electron which fell on this level and "hole" in the lower zone are space divided so that the probability of their recombination substantially decreases and leads to the anomalously long recombination time. In his subsequent works DI developed this basic idea and, in particular, investigated the kinetics of phosphorescence and he was the first to explain the experimentally observed luminescence behaviour with time. Further he turned to the effect of rectification of current by semiconductors and found a simple and correct explanation of this phenomenon. The essence of his explanation is based on the fact that near the contact of two semiconductors the gradient of electric field leads to the appearance of a space charge and, therefore, to a change in the electrical conductivity. However, the sign of this change depends on the direction of current that causes the rectifying action of the system. These and subsequent basic works of DI, in particular, the development of the theory of heteropolar and colored crystals, and the theory of electrical breakdown of dielectrics played an important role in the development of studies in quantum solid state theory and in practical use of their results. Already in his early works he showed up a deep understanding of the essence of quantum mechanics and originality of thinking anticipating a further development of physics. Especially characteristic in this respect is the work on calculation of "spectral line shift" caused by a reverse action of radiation. The work actually contained the theory of the Lamb shift, opened only ten years later and served as the beginning of quantum electrodynamics. The formula obtained by DI for the Lamb shift differs from the famous one of H. Bethe only by a numerical coefficient, which appeared as a result of the ultraviolet cut. The work was reported at the seminar in the Lebedev Physical Institute in 1938. Unfortunately, this very important discovery was not understood by contemporaries and the article was rejected by the editorial staff of JETF. It was published only in 1958 in the collection of Blokhintsev's works, although its results were cited earlier in the review by Ya.A. Smorodinsky (Uspekhi Fizicheskikh Nauk, 1949, v. 39, p. 325). In 1935 D.I. Blokhintsev was elected professor of the Department of Theoretical Physics of MSU. From that time and to his last days of life his activity was tidily connected with the Physical Faculty of MSU, where he managed the chair of Nuclear Physics and prepared many generations of specialists. DI was one of the organizers of the Department of Nuclear Physics of the Physical Faculty of MSU and creator of the Dubna branches of MSU and of the Moscow Institute of Radio Engineering, Electronics and Automation, whose tasks were to approach the student audience to research laboratories. DI liked the student audience. He was a frequent guest in a student hostel. Among his students there are many well-known scientists who produce a worthy contribution to the development of science."Science - he said - is a matter of talent and vocation, and now science is also a matter of a team. Nevertheless, among scientists, regardless titles and the fact who they are - graduate or PhD students - is a special category of people obsessed by passion to science, scientists whose great talent only seldom gives gladness to them but often causes a constant flour of dissatisfaction to achievements. Just on these rare brittle people entire success of an Institute is based. These people are usually unpractical, they are easily hurtled and vulnerable, they must be taken care of, they are necessary to be guarded, they are white cranes". Dmitrii Ivanovich created and read many fundamental theoretical courses, among which especially should be mentioned the course of quantum mechanics, which composed the basis of the first in the world university textbook. It has withstood 22 publications since 1944 - six in our country and 16 in other countries in the world in nine languages. Many generations of student-physicists were brought up on it. For his successes in quantum mechanics D.I. Blokhintsev was awarded the State Prize. From 1935 through 1950, besides the teaching activity in MSU, DI worked in the Lebedev Physical Institute. In the same years, he was a member of the Scientific Council of the Physical Institute in Kiev (Ukraine), where he supervised works of young Ukrainian physicists. After liberation of Kiev from fascist occupation he took active part in the restoration of science in the Ukraine. Blokhintsev's attention in the pre-war years was concentrated on fundamental questions of quantum mechanics. This activity continued also in the postwar period. He established a relation between the quantum description of a system of particles in the phase space and its classical distribution function. In particular, he revealed the impossibility of direct transfer into classics of quantum condition of the indistinguishability of identical particles. He first introduced the concept of "quasi-probability" (1940) at which Dirac arrived much later. He established that the diffraction pattern not always gives a possibility for unambiguous judgment about the form of the observed object. Objects of various forms can give similar diffraction patterns. He showed also that under some conditions it is possible to see an atom with the aid of an electron microscope. He showed that the "detailed balance principle" can be broken in spite of time reversibility. D.I. Blokhintsev is the author of the quantum ensemble concept. On the basis of this concept he gave an objective treatment of the wave function. This approach, being of large heuristic value, helps removing a number of internal contradictions in the interpretation of quantum mechanics and established a close connection between quantum mechanics and statistical physics. This concept of the "Moscow school" gives the modest role to an observer and emphasizes everywhere the objective nature of the quantum ensembles and regularities controlling them. He was the first to realize the special role of a classical instrument in quantum mechanics as an unstable state of a macroscopic system. It was an important step in overcoming the barrier, set by Nils Bohr authority, who considered that there is no sense in uniting a measuring instrument with a microscopic system, since then another classical instrument will be required for studying the integrated system. The works by D. Blokhintsev played an important role in formulation of methodological basis of contemporary quantum theory. In the preface to his book "Fundamentals of quantum mechanics" (fifth edition, 1976) he wrote: "I always gave much importance to the correct methodology without which even the most outstanding mind acquires the nuance of handicraft. Therefore, the materialist methodology, sometimes clearly sometimes less clearly pierces the entire book". In more detail these questions were considered in his monographs "Fundamental Questions of Quantum Mechanics" (1966) and "Quantum Mechanics (Lectures on selected questions)", 1981. During the years of the second world war DI almost completely turned to work on the military subjects in the field of acoustics and soon became the leading specialist in this field creating the acoustics of inhomogeneous and moving media. On the basis of the gas-hydrodynamics equations he obtained the equations of acoustics for the most general case ("Blokhintsev's equation") of which he derived a number of acoustic laws, explained and calculated diverse acoustic phenomena in the moving and inhomogeneous media (including the turbulentenes) which concern, on the one hand, the mechanism of generation of noise and, on the other hand, methods and means of its reception. In particular, the sound produced by propellers, the excitation of resonators by a gas flow and methods of reduction in this excitation, protection of the sound receivers from the large- and small-scale fluctuation of the incident flow and a number of others problems forming the basis of the theory of acoustic location of aircraft and submarines. He formulated the equations of geometric acoustics. He introduced an extremely fruitful concept of the pseudo-sound as a phenomenon which possesses the formal criteria of sound, but which is not an acoustic process. In some manifestations the pseudo-sound is identified with the Rayleigh waves or with the Fresnel zones of radiation in the electrodynamics (although does not reduce to these phenomena). He formulated the theorem which determines a necessary and sufficient condition for generation of sound during the motion of a body in the liquid or during the motion of liquid. Further development of this question led him to the conclusion that the basis of any emission, including acoustics, are the phenomena analogous to the Vavilov-Cherenkov effect. He emphasized high fruitfulness of this acoustic and electrodynamic analogy. For these works D.I. Blokhintsev was awarded the Order of Lenin (1946). Subsequently they were united in the monograph "Acoustics of an Inhomogeneous Moving Medium" (1946), published twice in USSR and abroad which is now the classics of a large intensively developing branch of physics. Almost every work in physics of noise in the turbulent boundary layer which arose on fuselages of modern liners or noise of exhaust jets of their engines refer the Blokhintsev's book as a basis of new acoustics. In the last years of the war and in the postwar years the task of usage of atomic energy became vitally important for our country. Beginning in 1947, Dmitrii Ivanovich actively worked on the development of Soviet atomic science and technology headed by I.V. Kurchatov. Igor Kurchatov made a great impact on his formation as a leader of large scientific and technical projects capable of uniting a collective and to inspire it for reaching a result. Kurchatov saw in an outstanding theoretician the talent of a big organizer and research engineer. Since then the name of D.I. Blokhintsev is inseparably connected with the history of the peaceful atom. Together with Kurchatov, he became the initiator of the creation of the world first atomic power station (Obninsk). In his book "Birth of the peaceful atom" DI wrote that "... he was lucky to participate in the great epic of the creation of Soviet atomic power engineering". In 1950 he was appointed the fist director of the Institute of Physics and Power Engineering in Obninsk, and also the scientific supervisor of creation and putting into operation of the the world first atomic power station ("Atomnaya energiya", v. 44, no. 6, 1979). To him belong the physical and design calculations of the reactors of this first APS. In the middle of 1954 the first APS gave current. A long-standing successful operation of the station confirmed the correctness of choosing the reactor type and basic parameters of the first APS. For this work D.I. Blokhintsev was awarded the Lenin prize (1955). His talk on the first APS in Obninsk was the main one at the first International Conference on Peaceful Use of Atomic Energy in Geneva (1955). In the subsequent years he calculated and supervised the development of design and construction of a new type of reactors -- the promising, in industrial sense, fast-neutron reactors with the liquid-metal heat-transfer agent. Now such reactors are exploited at other APS. He also developed the effective methods of calculation of slow and intermediate neutrons reactors. For the fulfillment of important State tasks in creation of atomic power engineering D.I. Blokhintsev was awarded the title of Hero of Socialist Labor (1956). Reactors attracted Blokhintsev's attention not only as the basis of power plants, but also as an intensive neutron source for diverse scientific studies. He is the author of the remarkable invention (1955) -- the fast pulsed reactors (IBR-1 and IBR-2), the pulsed power of which at a very small mean power is competitive with the most powerful reactors of a constant action. The first reactor of this type, IBR-1, was built and put into operation in Dubna in the Laboratory of Neutron Physics under the scientific leadership and with the direct participation of DI (1960). (He frequently called it his "dowry"). After many years of work this reactor proved to be a remarkable tool for studies in nuclear physics, physics of liquid and solid states and elementary particles physics. For this work D.I. Blokhintsev was awarded the State Prize (1971). During the subsequent years he was the scientific leader of the design and construction of a more advanced and powerful reactor IBR-2. He led its physical start (1977) and to the last days of his life the preparation of its power start. Now this last engineering creation of DI gives interesting physical results. DI initiated the creation of the Joint Institute for Nuclear Research. In 1956 the Committee of Plenipotentiaries of eleven countries unanimously elected him the first Director of this Institute. The leading scientists of the Soviet Union and other JINR Member States were drawn in the work at the Institute. In addition to the two existing in Dubna Laboratories - Laboratory of Nuclear Problems and Laboratory of High Energies, three new Laboratories were created: Laboratory of Nuclear Reactions, Laboratory of Neutron Physics and Laboratory of Theoretical Physics. The last two - on the initiative of Blokhintsev. During the period of his stay as Director (1956-1965) the Institute was finally organized and converted into the largest scientific research center which won high authority and international recognition for his research. It became the smithy of the scientific staff of the Member States. During the subsequent years (1965-1979) Blokhintsev headed the Laboratory of Theoretical Physics. He also made a noticeable personal contribution to the world scientific authority of Dubna. Fundamental problems of theoretical physics always drew DI's attention. In 1957, based on the "deuteron peaks" in the reactions of quasielastic high-energy proton scattering on nuclei, discovered by the group of M.G. Meshcheryakov, he proposed and developed the idea of fluctuations of nuclear density, capable as a whole to receive a large momentum transfer. The idea of "Blokhintsev's fluctons" best manifested itself 20 years latter when in reactions with relativistic nuclei the so-called "cumulative" particles were discovered. Later on DI participated in the development of the multi-quark interpretation of fluctons. Just they were the subject of the last DI's report at the Tokyo Conference on High Energy Physics in the fall of 1978. These studies grew now in the new promising direction - relativistic nuclear physics. In particular, just the presence of multi-quark states explains the "core" of nuclear forces. The remarkable confirmation of the flucton idea was obtained in experiments at CERN for deeply inelastic scattering of muons on nuclei and in the production of cumulative protons by a neutrino beam at Serpukhov. In the same years he investigated (on the basis of the optical "eikonal" model) the structure of nucleons, established its division into the central and peripheral parts and came to the conclusion about the dominant role of peripheral interactions. He showed the contradiction of the hydrodynamic approach to the multi-particle production processes with the basic principles of quantum mechanics (1957). The force of this criticism increasingly more begins to appear now as more correlation and spin measurements are carried out. Dmitrii Ivanovich proposed the idea of existence of several vacua in quantum field theory and spontaneous transition between them (1960). This idea is intensively used in contemporary unified theories of elementary particles. He was the first to point out the possibility of existence of the so-called "unitary limit" in weak interactions (1957) and the limit of applicability of quantum electrodynamics. A large and important cycle of his works was dedicated to quantum field theory, nonlinear and nonlocal theories, non-Hamiltonian approach, and stochastic space-time geometry. In particular, he showed the possibility of breaking the finite time signal propagation "in the small" without the essential breakdown of this fundamental law in the macrocosm. D.I. Blokhintsev proposed a new approach to nonlocal fields based on the hypothesis of stochastic fluctuations of the space-time metrics. Investigating substantially nonlinear fields, DI came to the conclusion that the concept of point-like coordinates becomes meaningless and requires a change in the geometry of microcosm if the mass spectrum of particles is bounded from above. These questions found their reflection in the book by D.I. Blokhintsev "Space and Time in the Microworld", published in 1970 and in 1982 in our country and repeatedly republished abroad. Considerable time was spent to searches for a non-Hamiltonian S-matrix method in the field theory which would replace the traditional Hamiltonian formalism. Blokhintsev proposed the specific version of the mathematical apparatus of this method (1947) based on the introduction of the "elementary scattering matrix". This apparatus gave the results which coincided with the approaches of usual relativistic invariant perturbation theory. The creative activity of Dmitrii Ivanovich did not fade to his last days. He investigated the problem of anomalously short time of the ultra-cold neutrons (UCN) storage and proposed the simple mechanism of explanation of this effect -- heating of UCN by hydrogen adsorbed by surface. He worked at one of the most complex problems, confinement of quarks, and proposed the original hypothesis for the nature of this phenomenon. In the last few years his thoughts repeatedly returned to the "Big Bang" in cosmology. Analyzing Friedman's model he arrived at the conclusion that the visible part of our universe could not be formed within the limits of four-dimensional space-time and proposed his original hypothesis of the existence of extra space dimensions, meta-space, in which meta-bodies and antibodies collide. Our Universe could be formed as a result of such a collision DI always took a great interest in the philosophy and methodologies of science. He repeatedly had to defend in discussions the idea of materialism from both his opponents and primitive defenders. Much attention was given by him to defence of the energy conservation law as the basis of materialistic natural science and the correct understanding of the theory of relativity and atomic theory. In his first book "What is the theory of relativity?" he gave not only comprehensible exposition of this theory, but also its first correct interpretation. Special importance he gave to his last work "On the Relationship of Applied and Basic research" where, being based on the specific features of man as a biological form -- inquisitiveness, extended transmission of information from one generation to the next one, which caused the detachment of man from the remaining living world, the needs for the emotional contact with the external world -- he came to the conclusion on inevitability of increase of the activity of people in the production of ideas. Very interesting are his unpublished "Science and Skill" and "Essays on the Materialistic Philosophy". His gift of foresight appeared not only in his scientific and philosophical works, but also in the organization of conferences, in particular, conferences on nonlocal quantum field theory (which, actually, were conferences on fundamental problems of field theory) in the period of its almost complete refusion when it was necessary to have courage to foresee its subsequent renaissance. He was the permanent chairman of these unique conferences during 1964-1979. In accordance with his understanding of creative activity, DI proposed such organization of conferences, which would give to its participants as much the leisure as possible (not the rest, but the leisure - in that sense of this word, what ancient Greeks put into it, and which is so small in the contemporary life). He considered it useful not only to listen to reports, but even more useful to converse with interesting men. The conferences and the workshops organized under his leadership, thoroughly planned, gave participants the possibility of maximum of self-realization. This was one of the reasons for a constant increase of their popularity. To him belongs a big role in the establishment of the first scientific exchanges between CERN (Geneva) and JINR, in the organization of many international conferences and symposia, including the so-called Rochester conferences - the largest conferences on high-energy physics. D.I. Blokhintsev was the outstanding public figure: the member of the Soviet Peace Committee, the scientific adviser of Secretary General of the UN, Vice President (1963-1966) and President (1966-1969) of the Union of Pure and Applied Physics (IUPAP), the member of the USSR State and Lenin Prizes Committee and a large number of commissions, scientific councils and editorial boards. Blokhintsev's merits were recognized by the highest Soviet and foreign rewards -- the title of Hero of Socialist Labor, Lenin and two State prizes winner, four Orders of Lenin, the order of the October Revolution, the Order of the Red Banner of Labor, the nominal gold medal of the Academy of Sciences of Czechia, the order of Cyril and Methody of 1-st degree (Bulgaria), the highest orders of Romania, Mongolia, and many other orders and medals of the USSR and other countries. The public activity D.I. Blokhintsev was marked by the honorable certificate of the World Council for Peace (1969). He was chosen member of the Academies of Sciences of many countries and the honorable doctor of a number of universities. Scientist, citizen he in his articles and presentations repeatedly emphasized that the scientist must not be locked in the professional shell: "...Our duty, great duty of scientists and engineers of our time, and no one must escape from this, is to explain to all people what threat will hang over the world and let then the wrath of entire humanity stop the madmen of atomic warfare". The many-sidedness of D.I. Blokhintsev, his universality appeared not only in the scientific but also in the aesthetical perception of the world. He was original poet and artist whose pictures were repeatedly demonstrated at exhibitions and their reproductions were published in periodicals and newspapers. Through entire life he carried love for the poetry. His many verses were published in the periodicals and in the collection "Muza in the Temple of Science" (1982). But the main part of his verses still awaits for publication. In his pictures and verses he is a fine psychologist, attentive observer, deep philosopher. He deeply understood the process of creative thinking directed for the creation of a new in science and skill. "Creation - he said -- is not volitional event but the special state of spirit and intellect which implicates into the process of thinking rich aesthetical experiences". The personal charm of ingenious collocutor, the unique combination of calmness and boiling creative energy which he always generously shared left lasting impression. The essence of his personality is possible to express briefly - the creation. Personal contacts with him enriched the collocutor. He began to feel himself as a creative personality and acquired the belief in his own forces.