Lev Landau. Kharkov. 1934 (Photo by D. Gai)

The 90th birth anniversary of Lev Davidovich Landau, one of the most outstanding physicists of the XX century, falls on January 22, 1998.

L.D.Landau made immense contributions to quite different fields of theoretical physics. He was not only a great scientist possessing a rare universalism, but also a unique Teacher with a capital T. He founded a world-famous school of theoretical physicists who also contributed significantly to the development of physical science through their works. Landau was an outstanding teacher who read brilliant lectures not only on theoretical physics, but also on general and elementary physics. The ethical image of Landau is also enviable, and he is remembered for his refusal to compromise on basic matters, kindness and goodwill, as well as the moral support he extended to budding scientists in their hour of need.

Landau led a magnificent and yet tragic life. He became a legend in his lifetime, and rightly so, since he attained exceptional success in his scientific activity and also came face to face with death on two occasions. The first time was in 1938 when he was arrested by the NKVD agents as an "enemy of the people", and the second time it was a bizarre car accident in 1962.

He was saved on the first occasion by Petr Leonidovich Kapitza. This was a heroic feat, as Kapitza did not flinch and wrote a letter directly to Stalin the very next day after Landau's arrest. In his letter, Kapitza gave Landau an excellent testimonial and pleaded, "... in view of his exceptional talent, to give appropriate instructions to consider his case with extreme care... I also feel", wrote Kapitza, "that we must take into consideration his temper which can be called nothing but outrageous. He is a tease and a bully, loves to find faults in others and having found them, especially in pompous old men like our academicians, starts mocking them disrespectfully. This has earned him many foes... But in spite of all the drawbacks in his disposition, I find it very hard to believe that Landau could do something dishonorable."

Landau was spared from a savage reprisal. Owing to the stupendous efforts of Kapitza, Landau was set free. However, the charges against him were not withdrawn, and he was released under Kapitza's guarantee. The courage and fortitude of this great man and scientist deserve all praise. It was indeed a heroic deed during such hard days. In all other organizations, a general staff meeting would be called on the day following the arrest of an "enemy of the people", where the Director, striking his chest with his fists, would thank Yezhov's agents for helping unmask a "fierce enemy of the people who had concealed himself unostentatiously in our team''. However, Kapitza did not call any such meeting, did not engage himself in any breast-beating or confession of the sins he had never committed, but threw himself with rare fortitude to save an absolutely innocent person and conquered. The scientific community owes him a debt of gratitude for this.

Landau's rehabilitation came only in 1990, many years after his death. Thus starting from April 28, 1939, the day he was released, right until his death on April 1, 1968, he remained accused and "adequately exposed as a participant of the anti-Soviet group''.

The collected works of Landau contain only one paper by Landau on electromagnetic showers published during 1938, the year of his arrest. In 1939 also, there was only one work on the de Haas-van Alphen effect which had actually been written much earlier. However, a large number of papers started appearing from 1940 onwards. This is due not only to the fact that Landau had been freed, but also because he was on very good terms with Petr Leonidovich Kapitza, who was sympathetic towards Landau. So closely related were the interests and works of these two magnificent scientists that the Institute of Physical Problems was called the Kapitza-Landau Institute abroad.

The second tragedy struck on January 7, 1962 when Landau, driven by some "evil force", decided to go by car to Dubna in spite of a road made highly slippery with ice. His savior angel Kapitza was not around to dissuade him from undertaking the journey. The car in which Landau was travelling collided with a truck, and Landau received fatal injuries which were not compatible with life according to the medicine luminaries of Moscow. However, Landau's life was saved, thanks to the heroic efforts of the doctors, nurses, and the united efforts of physicists from all over the world who acquired the necessary medicaments and sent them by air to Moscow. The battle to save Landau's life was launched in the true sense of the word and was won only formally, since only the body of Landau could be saved while his intellect was lost. It was awful to watch Landau without his brilliant intellect. The only redeeming point was that Landau did not feel nor realize the magnitude of the tragedy. If someone approached him with a scientific question, Landau would usually ward him off saying, ' 'let us discuss it tomorrow." His memory preserved only his knowledge of foreign languages which he had mastered perfectly.

Lev Davidovich Landau was born on January 22, 1908 in Baku. His father was a petroleum engineer, and his mother was a doctor. Landau's mathematical talent was revealed in early childhood. He remarked later that he could not remember when he had learnt differentiation and integration. At the age of 14, Landau joined the Baku University from where he moved to the physics department of the Leningrad University from where he graduated in 1927.

This was a period of tumultuous growth of the new physical theory called quantum mechanics. The scientific career of Landau was thus related closely with all stages of growth of this important physical theory. Landau had to work a lot to keep pace with the new science. He even suffered from nervous exhaustion at one stage, lost his sleep, but managed to withstand the strain.

Landau's friends G.A.Gamow and M.P.Bronshtein went on to become renowned physicists. Gamow created the theory of alpha decay of nuclei, predicted the existence of relict radiation left by the Big Bang marking the formation of our Universe. He was one of the first to explain the genetic code associated with the structure of genes. Bronshtein was the first to quantize the gravitational field.

In 1929, Landau was sent abroad by the Peoples' Commissariat on Education, and spent one and a half years working in Denmark, England and Switzerland. The most important of his visits was in Copenhagen where theoretical physicists from all over Europe gathered at the Theoretical Physics Institute of the great Niels Bohr and discussed the fundamental problems of contemporary theoretical physics at the famous seminars conducted by Bohr. The scientific atmosphere, augmented by the charming personality of Bohr, had a decisive influence on the formation of Landau's outlook on physics, and he always considered himself to be a pupil of Niels Bohr. Later, he visited Copenhagen on two occasions in 1933 and 1934.

On his return to Leningrad in 1931, Landau worked at the Leningrad Physicotechnical Institute from which he moved to Kharkov in 1932, to work at a new research center, the Ukrainian Physicotechnical Institute (UPTI).

This institute was founded in 1928 following the decision of the Ukrainian government at the initiative of Academician Abram Fedorovich Ioffe, a leading organizer of Soviet physics. As the foremost task, Ioffe pointed towards the need to "decentralize physics", i.e., to create a network of physics institutes all over the country instead of confining them to just Leningrad and Moscow. As the first step, he emphasized the need to create a powerful physics institute in Kharkov, an important industrial center of the country and the capital of the Ukraine. (The capital of the Ukraine was shifted to Kiev in 1934 under orders from Stalin.)

The core of the staff at UPTI was formed by physicists migrating from the Leningrad Physicotechnical Institute (LPTI). The group of scientists leaving for Kharkov were seen off at the railway station with fanfare since their departure was seen as an important patriotic step.

A famous architect of Leningrad designed the building for the new institute according to the project of its future director Ivan Vasil'evich Obreimov. The UPTI building turned out to be an excellent structure.

Many talented scientists including I.V.Obreimov, A.I.Leipunskii, L.V.Shubnikov, K.D.Sinel'nikov, A.K.Val'ter, V.S.Gorskii, G.D.Latyshev, A.F.Prikhot'ko, O.N.Trapeznikova, and L.V.Rozenkevich migrated from Leningrad to UPTI.

L.D.Landau was invited to work at UPTI by I.V.Obreimov, the Director of the Institute. Many years later, Ivan Vasil'evich told the author that Landau was underestimated at UPTI, and Obreimov, who knew how talented Landau was, offered him the post of head of the theoretical physics division and gave him full freedom in preparing young theoretical physicists and in the choice of the scientific topics. In effect, Obreimov created the first division of theoretical physics of this kind in any physics institute of the country. It can be stated that the formation of this division and the migration of Landau to UPTI was facilitated by the complex relation between Ioffe, the director of LPTI, and Landau who was an outspoken person and did not hesitate to criticize some specific works of Ioffe on thin-film insulators. According to Landau, these works were fallacious.

Landau's task was quite obvious from the very beginning: it included organizing the theoretical department, discovering talented youth and supervising them, theoretical physics studies and teaching in Kharkov educational institutions, writing of books and reviews on theoretical and general physics, and creative contacts with the experimenters at UPTI.

After Landau's arrival in Kharkov, UPTI became one of the best centers of theoretical physics in the world. The "Journal of Soviet Physics", which began to be published at the Institute, acquired worldwide fame.

An International Conference on Theoretical Physics was held in Kharkov in the summer of 1934. The conference was attended by Niels Bohr and many leading theoretical physicists both from the Soviet Union and abroad. These included V.A.Fock, I.E.Tamm, Ya.I.Frenkel', E.Williams, R.Peierls, I.Waller, and others. One could see Bohr and Landau walking in the courtyard of UPTI and engrossed in a lively discussion of physical problems.

During this period, leading physicists like P.Dirac, V.A.Fock, R.Peierls, V.Weisskopf, H.Placzek and G.A.Gamow visited UPTI and worked there, frequently for long periods.

Let us now turn to the scientific and organizational work of Landau in establishing the theoretical physics department. The main idea was that a young scientist, who wanted to devote his life to theoretical physics and to work under the guidance of Landau for this purpose, had to pass the so-called theoretical minimum examination conducted personally by Landau and covering the main branches of theoretical physics.

The theoretical minimum included classical mechanics, fundamentals of statistical physics and thermodynamics, continuum mechanics, special theory of relativity and classical electrodynamics, electrodynamics of continuous media, general theory of relativity and gravitation, nonrelativistic quantum mechanics, relativistic quantum mechanics, quantum statistics and kinetics. In addition, it was essential to possess adequate knowledge of mathematical analysis, differential equations and the theory of functions of complex variables. The programs of theoretical minimum were worked out meticulously by Landau himself with a view to avoid any overcrowding with superfluous details complicating the task of the examinees. Only the most important topics were selected. The same yardstick was used for mathematics. Landau did not ask for the proofs of various subtle theorems. All that was required was a quick evaluation of integrals, the solution of the basic differential equations, and the application of the theory of functions of a complex variable.

In all, eight examinations had to be taken in various branches of physics, in addition to one in mathematics. A budding scientist after passing the theoretical minimum was taken into Landau's group and could even address him familiarly as 'thou'. Landau assigned a scientific topic to those passing the theoretical minimum. This assignment had to be completed independently without Landau's help, and would eventually form the material for a Ph.D. thesis.

A.S.Kompaneyets and E.M.Lifshitz were the first to have passed theoretical minimum in Kharkov and to become pupils of Landau. The author was the third, and I.Ya.Pomeranchuk the fourth. Laslo Tisza was the fifth to pass the examination. A total of 43 persons passed these tests between 1934 and 1961.

A Faculty of Physics and Mechanics was opened in the Mechanical Engineering and Machine Building Institute in Kharkov, on the lines of the Physics and Engineering Faculty at the Leningrad Polytechnical Institute. The department of physics at this faculty was headed by I.V.Obreimov. Landau headed the chair of theoretical physics at this department. In 1935 he became the head of the department of experimental physics at the Kharkov University. Landau involved the staff of the theoretical physics department headed by him at UPTI in teaching activity. Teaching was an essential part of staff activity and was carried out in rotation, i.e., each member taught different courses in different years. Thus, theoretical physics and general physics were mastered in the best possible way by the young scientists.

Landau attached a lot of importance to the teaching activity, and his teaching methods and programs can truly be called revolutionary. Let us cite a few examples. Before Landau, theoretical mechanics was taught independently of theoretical physics, and in the most archaic manner at that, even without the use of vector algebra. But mechanics, after all, is the very basis of theoretical physics. Hence Landau combined the subject of theoretical mechanics with theoretical physics and made it the first subject that was taught in the general course on theoretical physics. The presentation of theoretical mechanics was based on the variational principle and the introduction of Lagrangian functions. This established a connection with the subsequent sections of theoretical physics and a common approach for understanding theoretical physics as a single entity. Much attention was paid to explain the properties of the space-time symmetry and to force interactions. A book containing problems in mechanics was published, and exercises from this book were solved by the students. Unfortunately, no subsequent editions of the book were published.

The second important reform concerned the presentation of the fundamentals of electricity and magnetism. According to Landau, Einstein's special theory of relativity had to be taught before electrodynamics, and a large number of problems had to be solved before the field theory and Maxwell's electrodynamics could be touched. We shall not go into details of the manner in which other sections of theoretical physics were taught, although many important and interesting steps were taken, especially in the description of quantum mechanics. Let us dwell a little on the teaching of general physics.

Landau himself started teaching general physics to the first-year students at the physics faculty. The subject covered mechanics and molecular physics. A large number of pitfalls still plague these topics. These include the introduction of the concepts of mass and force, the definition of inertial reference systems, Newton's laws, the concept of temperature, irreversibility of thermal phenomena, and the introduction of the concept of entropy. All these concepts were presented in a simple, clear and logical manner by Landau who never used excessive mathematics and avoided the description of experimental details which could only obscure the clear physical picture. The main experiments were demonstrated at the lectures. In Kharkov, this was done by a special assistant. Later, when Landau taught this course at the Moscow State University, the demonstration of the experiments was done by P.L.Kapitza. Thus the course on general physics in Moscow was taught jointly by Landau and Kapitza.

Landau's lectures on general physics at the Kharkov University were so magnificent that they were attended not only by the staff of the theoretical physics department, but also by leading scientists like L.V.Shubnikov, V.S.Gorskii, and L.V.Rozenkevich.

Landau was a great patriot and considered it very important to raise the level of teaching physics in the country. He wanted to enlist in this task the support of higher authorities and requested an audience with N.I.Bukharin, who was a member of the Politbureau of the Central Committee of All-Union Communist Party (Bolsheviks). Bukharin received Landau who was fascinated by the former and even published an article "Bourgeoisie and Contemporary Physics" in Izvestiya of November 23, 1935. The very title of the paper shows that Landau was devoted to the ideas of socialism, highly valued the scientific contribution of Marx and, like Einstein, held Lenin in great esteem. It is not for nothing that in Copenhagen, Landau was considered at least ' 'pink'' if not "red". He went to Copenhagen on three occasions and returned to his motherland each time. It should be pertinent to mention here that N.I.Bukharin evinced a keen interest in the achievements of physical science when he received Landau, and listened to Gamow's lecture on nuclear power in Leningrad. He even offered Gamow the facility of all electric power stations of Leningrad for one night for experiments on releasing nuclear energy. N.I.Bukharin, the real initiator of thermonuclear research in the USSR, was later executed as an "enemy of the people".

Reforms in the teaching of physics hurt the interests of many representatives and professors of the old thought to whom Kapitza referred as "pompous old academicians" in his letter to Stalin. Animosity and resentment against Landau were rising and looking for an opportune moment to surface. Such an opportunity arose after the murder of S.M.Kirov, the Secretary of the Leningrad Regional Party Committee, when Stalin's reign of terror began.

Landau was dismissed from the university in March 1937. The reasons for his dismissal were not mentioned in the order, but it turned out later that Landau was removed due to his propaganda of idealism. Evidently, he was made a victim of slander and denunciation.

As a mark of protest, Shubnikov and other members of the theoretical physics department working at the university tendered their resignation. This was treated as a strike, and the entire group was summoned to Kiev by the minister of higher education V.P.Zatonskii. Discussions with Zatonskii clearly revealed the contents of denunciations against Landau. At the end of the meeting, the minister advised the "strikers" to return to their place and continue working. However, Landau returned to his work.

Meanwhile, the atmosphere at the UPTI also started becoming unfavorable for Landau. The leadership of the Institute started giving preference to second-rate works over Landau's outstanding works, and even started dubbing the former as works significant for the defense of the country.

Landau decided to go to Moscow and work with P. L. Kapitza for whom the USSR government had built a new, first-rate institute. In the spring of 1937, Landau finally moved to Moscow and became the head of theoretical division at the Institute of Physical Problems. He remained at this post for the rest of his life. The multifaceted genius of Landau was revealed to the fullest extent at this Institute which became like home for him.

Moving to Moscow was the wisest step taken by Landau, for it saved his life. Stalin's terror had begun and was spreading. Revelling in denunciations and slander, demons unleashed their bloody atrocities, mocking, torturing and killing absolutely innocent people.

At night people feared the arrival of ' 'ravens'' (special cars for arrested people). Finally they came to the UPTI courtyard also and took away remarkable people and excellent scientists like Shubnikov, Gorskii and Rozenkevich for slaughter. Had Landau remained in Kharkov, he would have inevitably met the same fate as Shubnikov and other friends and would have been executed. The wave of terror engulfed Landau in Moscow only after a year, and he remained alive only owing to Kapitza's intervention.

Among the experimenters at UPTI, Landau was closest to Lev Vasil'evich Shubnikov, one of the most famous and prominent physicists of our time, one who made remarkable discoveries. For example, he discovered that magnetic field cannot penetrate a superconductor, and that the resistance variation of bismuth in a magnetic field is oscillatory in nature. Landau kept himself abreast of all the works of Shubnikov. They discussed scientific problems jointly, and their continued interaction enriched both. After moving to Moscow, Landau interacted with P.L.Kapitza more than any other experimenter. There is no doubt that the brilliant discovery of superfluidity of helium II by Kapitza led to the emergence of an equally brilliant work by Landau on the theory of superfluidity of quantum liquids.

Landau's activity in Moscow was an "analytical continuation" of Landau's work in Kharkov, if one may say so. His ideas and plans were the same, but their magnitude and scope grew enormously. It was the same theoretical minimum, the same seminar, the same favorite work, the same task of writing books and papers, and the same connection with experimenters, but all this activity now involved new people not only from Moscow, but from all over the Soviet Union. New brilliant students appeared as well as new remarkable results of Landau's multifaceted genius.

Landau's seminar was transformed into a weekly gathering of physicists in Moscow, which was attended by scientists from Leningrad, Kharkov, Kiev, Tbilisi, and other cities. It was not a simple matter to speak at Landau's seminar since Landau treated the material to be discussed very critically. However, it was always a great honor for a scientist to present the results of his work at the seminar, and Landau's approval was the ultimate praise one could hope for. A situation arose in which Landau became the highest authority for theoretical physicists, and his opinion was the last word not only for young specialists, but for prominent scientists also.

What did Landau achieve? His legacy is enormous and covers literally all branches of theoretical physics.

In quantum mechanics, Landau introduced the density matrix in 1927 independently of von Neuman. This work shows the depth to which the 19-year old youth had grasped the ideas of quantum mechanics.

In 1931, Landau completed a fundamental work together with R. Peierls, analyzing the uncertainty principle in the relativistic region and setting new constraints on the measurement of various dynamic variables.

Landau evinced a very keen interest in the problems of quantum electrodynamics. As early as 1934, he studied the formation of electron-positron pairs during collisions of heavy charged particles. His works on determining the asymptotic forms of the so-called quantum electrodynamic Green's functions appeared in the fifties in coauthorship with A.A.Abrikosov and I.M.Khalatnikov. As a result of these investigations, Landau and Pomeranchuk arrived at the paradoxical conclusion that the real physical charge of the electron must be equal to zero owing to polarization of vacuum (so-called "nullification of charge" or "moscow zero"). The solution of the problem appeared much later following the emergence of non-Abelian gauge field theories, viz., the theory of strong interactions and the theory of electroweak interactions, combining the theories of weak and electromagnetic interactions. Unlike Abelian quantum electrodynamics, these theories also contain the antiscreening effect in addition to the charge screening effect. In the unified theory, antiscreening exceeds screening, which is characteristic only of the Abelian field theory. Hence charge nullification does not occur in real physics. One can only lament over the fact that unification of interaction came much too late for Landau and Pomeranchuk, both of whom having passed away by that time.

Studies of quantum electrodynamics were carried out in full swing in Landau's school in Moscow, Leningrad and Kharkov. However, Landau's interests were not confined to just these studies. The range and depth of his scientific interests were truly enormous. In our age it is hard, nay, impossible, to find a scientist with such a broad range or, in the language of physics, spectrum of interests. His universalism was truly unique as it was characterized by a rare insight into the essence of physical phenomena.

Landau predicted the existence of neutron stars (pulsars).

Landau created the theory of second-order phase transformations.

He constructed the theory of the intermediate state in superconductors. The Landau-Ginzburg equation has an enormous significance in the theory of superconductivity.

Landau's diamagnetism is quite famous.

Landau constructed the theory of superfluidity and the theory of Fermi liquids.

In the physics of elementary particles, Landau's contribution comes in the form of the two-component neutrino theory and the introduction of the concept of combined parity (independently of Lee and Yang).

Landau proposed a general approach for studying the peculiarities of Feynman diagrams.

Landau made significant contribution to the development of several branches of physics, like plasma physics and the physics of magnetism. But before discussing these subjects, it must be remarked that Landau always found the "appropriate mathematics" each time for each work. He had an excellent knowledge of mathematical analysis, but was essentially a pragmatist and did not indulge in profound mathematical theories. He even scoffed such an approach and mentioned that he knew mathematics because he had solved all the problems from the book "The Ten Sages". Of course, such a 'philosophy' had to be revised strongly at times. For example, his knowledge of group theory was evidently inadequate, and this became apparent when he created his theory of second-order phase transformations. Luckily for him, N.G.Chebotarev, who was a leading specialist in the subject of algebra, was visiting the Kharkov Mathematical Institute next to UPTI at that time. Landau and Chebotarev played tennis together, and this interaction helped Landau understand the theory of groups which was essential for constructing the theory of phase transformations.

Many mathematical papers by Landau were simply marvelous. For example, he obtained Mellin's transformation and Poisson's sum rules on his own, without knowing about their existence for a long time. Mellin's transformation was necessary for him to solve kinetic equations in the theory of electromagnetic showers constructed by him.

Landau arrived at Poisson's sum rule while constructing the general theory of the de Haas-van Alphen effect. It is significant each new "conjecture" was always pertinent to the theory being developed by him.

At the dawn of his career, Landau completed his classical work on the kinetic equation for the Coulomb interaction of particles. In this work, he established the form of the collisions integral in the Coulomb interaction. At the beginning, this work was treated as purely academic research. But as more and more scientists started studying the properties of plasma, plasma physics became one of the most important branches of science, especially in view of the possibility of creation of plasma thermonuclear devices. It was here that scientists recalled Landau's work on the kinetic equations in the Coulomb interaction of particles, and the collision integral came to be known as Landau's collision integral. Without this integral, one cannot solve the relaxation problem in plasma, the problem on the electrical conductivity of plasma, or the problem on plasma heating.

Let us now consider another plasma problem. Collisions of particles are rare in plasma, hence the starting mathematical equation for describing the properties of such a plasma is the kinetic equation that does not take into consideration the collisions between particles, but does include the self-consistent field of particles. This equation was first obtained by A.A.Vlasov and is called Vlasov's equation.

Analyzing the quantum equation of plasma without the collision integral, Landau came to the remarkable conclusion that plasma oscillations will attenuate in spite of the absence of collisions. He discovered attenuation of waves which is now called Landau damping.

Magnetism was an old fascination of Landau. During his deputation abroad, he determined the energy spectrum of an electron in a magnetic field (Landau levels) and used it in the problem on the magnetic properties of a free electron gas. He discovered that, in spite of the prevailing opinion, a gas acquires a diamagnetic moment in the quantum theory, which partially neutralizes the so-called Pauli's spin paramagnetic moment. In this connection, an argument arose between Landau and Pauli, and was won by the former.

The most important work by Landau in the field of magnetism concerned the movement of magnetic moment in a ferromagnetic. Together with E.M.Lifshitz, he constructed the equation of motion for the moment. This equation is used widely for studying various processes in magnetically ordered media. It is also especially important for studying oscillatory phenomena in such media.

Landau had an excellent perception of physics associated with magnetism. We can mention, for example, the simplicity and elegance with which he explained the macroscopic nature of Bloch spin waves and how clearly everything fell into place after this.

It should also be mentioned that Landau is the author of the first mathematical theory of the domain structure of ferromagnets.

It is impossible to cover in this brief review the entire scientific legacy of Landau. Speaking of Landau and recalling his famous scientific discoveries, we must compare them with rare and precious stones, which compose a sort of crown over Landau' head. However, there are ' 'many more smaller diamonds and gems", as the saying goes from the opera "Sadko", "not counting diamonds in stone caves". They were also scattered in his encyclopedic course on theoretical physics, in problems contained in this course, in the original derivations by Landau of many laws and relations.

The creation of this course was the task of a lifetime and a matter of pride for Landau. In conformity with Landau's wishes, the course was written in coauthorship with his closest pupil Evgenii Milhailovich Lifshitz. This course is really an epic in the true sense of the word, and theoretical physics has been taught for many decades with the help of these books all over the world. It can be stated with confidence that students will be using these textbooks not only in the 20th century, but in 21st as well!

Six volumes of the course were published during Landau's lifetime. These include mechanics, statistical physics, field theory, electrodynamics of continuous media, hydrodynamics and the theory of elasticity, and nonrelativistic quantum mechanics. Relativistic quantum mechanics and physical kinetics were published after Landau's death. (These books were written in coauthorship with B.B.Berestetskii and L.P.Pitaevskii.) Landau's course is incredible, for it is hard to imagine how one person could have possessed such a colossal amount of material. These volumes are not only splendid textbooks, but can be compared with Rayleigh's famous "Papers". If one starts investigating any specific question pertaining to macrophysics, one must first see what Rayleigh and Landau thought and wrote about it. This is especially true for fluid dynamics and macroscopic electrodynamics.

Landau was fully cognizant of the achievements in modern experimental physics, and this is equally true for the nuclear physics, solid state physics, and the physics of elementary particles. He always listened keenly to the experimenters describing their results. However, as was mentioned above, he was very close to two great masters in experimental physics Lev Vasil'evich Shubnikov and Petr Leonidovich Kapitza. Their experiments inspired Landau, and discussions with Landau helped Shubnikov and Kapitza.

Landau earned worldwide fame after moving to Moscow. He was elected a Member of the USSR Academy of Sciences in 1946. Later he won many orders, including the Order of Lenin twice, and the title of Hero of Socialist Labor. These awards were given not only for purely scientific achievements, but also for his contribution in fulfilling practical assignments of the State. He won three State Awards, and the Lenin Prize in 1962. There was no dearth of honors bestowed on him by other countries also. As early as in 1951, he was elected a member of the Danish Academy of Sciences, and in 1956 he was elected to the Dutch Academy of Science. In 1959, he became a member of the British Physical Society, and an Overseas Member of the Royal Society in 1960. In the same year, he was elected to the National Science Academy, USA, and to the American Academy of Arts and Sciences. Landau won the F.London award (USA) and the Max Planck medal (FRG) in 1960. Finally, he won the Nobel Prize in Physics in 1962 "for pioneering research in the theory of condensed state of matter, especially liquid helium."

Muscovites took pride not only in that the city housed the Kremlin, the Tret'yakov Gallery, and the Arts Theater, but also in the fact that Academician Lev Landau lived and worked in Moscow.

Six years after the tragic accident, Landau passed away on April 1, 1968. Scientists as well as people from different walks of life all over the world mourned the death of a genius, the passing away of a great scientist and teacher who left an indelible mark in the history of science and civilization.