Petr Kapitza in Cambridge.

Source: Photograph by and courtesy of the late David Shoenberg.

Petr Kapitza on Russian postage stamp, 1994.

4
Petr Kapitza
RESPECTED CENTAUR

Petr L. Kapitza (1894–1984) was one of the most brilliant representatives of the great generation of Soviet physicists. He made experimental discoveries in low-temperature physics, and in 1978 was awarded the Nobel Prize. He was also willing to risk his career and life when he stood up to one of the bloodiest dictators of word history. He dedicated his existence to physics, but was also a Soviet patriot.

Kapitza had proved his scientific acumen in Cambridge, England, and when in 1934 he was confined to the Soviet Union, he developed an internationally renowned research center. He took personal responsibility for persecuted and prosecuted scientists, such as the mathematician Nikolai Luzin and the physicists Vladimir Fock and Lev Landau, and probably saved their lives. He acted creatively under a variety of circumstances. He was autocratic but popular, respected and feared, yet has remained a role model in science.

When I became acquainted with Petr Kapitza’s name in the first half of the 1960s, he was already a legend.^* I never met him in person, but many years later my conversations with one of his pupils, David Shoenberg, brought Kapitza into human perspective for me.¹

Petr Leonidovich Kapitza was born on July 9, 1894, at the Russian naval base Kronstadt, near St. Petersburg. The Russian Navy was known for its high level of discipline and dedication. Kapitza’s father was a military engineer; and his mother (née Stebnitskaya), a teacher, specializing in children’s literature. Kapitza had an enriched upbringing; early on he was taken for trips, visiting Switzerland, Italy, Greece, Germany, Scotland, and extended regions of northern Russia. As a child, he was good in arithmetic, but less so in languages. He started his schooling in Kronstadt. First, he attended a “classical gymnasium,”^** but this school soon advised him to change to another one with an emphasis on “real” subjects. Today, his bust graces a spot near his first school, which did not find that he met their standards of scholarship.

Petr Kapitza’s bust in Kronstadt.

Source: Photograph by and courtesy of the author.

After secondary school, he became a student at the Faculty of Electrical Mechanics of the St. Petersburg Institute of Technology where Abram Ioffe attracted the young Kapitza to do research in his department. In 1914, World War I broke out, and in 1915, Kapitza volunteered to do service at the front as an ambulance driver and served for a few months. In 1916, he traveled to Shanghai, China, where his fiancée, Nadezhda Chernosvitova, was at the time. Together they visited Japan, and then returned to Russia and got married. The revolutionary events and the civil war had great impact on Kapitza’s family. His father-in-law was an official of a rightist party, and the revolutionaries shot him. Kapitza and Nadezhda had a son and a daughter, but more tragedy struck. Their son died of scarlet fever. Nadezhda and their newly born baby daughter died of the Spanish flu, as did Kapitza’s father. It took tremendous fortitude for Kapitza to hold himself together and continue his studies, which helped him survive this terrible period.

Kapitza’s first research papers on the physics of electrons appeared in the Russian-language Journal of the Russian Physical-Chemical Society. In 1917, he conducted his summer exercise under the renowned physicist L. I. Mandelshtam in the radio-telegram division of a Siemens plant. When Kapitza graduated as an electrical engineer, he was already a research associate of the Institute of Physical Technology.

During these years, Kapitza and Nikolai Semenov, another aspiring and gifted scientist, forged a friendship for life (see chapter 8). They suggested a new method for determining the magnetic moment of atoms, and coauthored a paper about it. They stopped at the theoretical considerations and never carried through the experimental test of their method. Kapitza’s characteristic approach to research had already manifested itself: he could be involved totally in a project, but could then be easily attracted to the next one, just as easily abandoning the previous one. Kapitza did not like to follow a trodden path, not even his own.

In 1921, Kapitza traveled to England as member of a Soviet science delegation whose mission was to renew scientific interactions with the West. In Cambridge, he was greatly impressed by what he saw there, and asked Ernest Rutherford to accept him to his Cavendish Laboratory. Rutherford declined saying that the Laboratory was full, and the matter might have rested there. However, Kapitza pointed out that adding one member would be within the experimental error of 3 percent that usually characterized Rutherford’s work in physics. Rutherford liked Kapitza’s unusual reasoning and impressed by the young man’s determination, he permitted him to stay. It was the beginning of a special relationship between the two physicists lasting a dozen years, until the end of Rutherford’s life. Kapitza, in the words of the British author, C. P. Snow, “flattered Rutherford outrageously, and Rutherford loved it. Kapitsa could be as impertinent as a Dostoevskian comedian: but he had great daring and scientific insight.”²

Indeed, the unusual Kapitza carried out remarkable deeds in Cambridge. He founded an informal seminar—a weekly gathering in his apartment—to report the latest results and ongoing work. It acquired the name Kapitza Club, which continued for a long time after Kapitza had left Cambridge. The venue was small, and not many people attended these seminars, but everyone important in Cambridge physics, including many visitors, gave a talk at the Club. The first session took place on October 17, 1922, and Kapitza talked about magnetism. Soon, they started a logbook, and each time, the presenter signed it next to the record of the topic. This logbook shows how up-to-date the topics of the meetings were. The terse comments hint also at occasional disagreements, which was natural since cutting-edge science was being discussed.³

The last session of the Kapitza Club before Kapitza was detained in the Soviet Union, was the 377th meeting, on August 21, 1934. The refugee scientist and future Nobel laureate Otto Stern spoke about the magnetic momentum of the deuteron. Then, in Kapitza’s absence, others took over the Club. World War II interrupted the activities, but the participants were eager to resume them after the war. For some time, Kapitza’s former British student, David Shoenberg, organized the gatherings.⁴ During the second half of the 1950s, the meetings became less frequent, and in 1958 they stopped. Officially, the closing meeting took place in 1966, on the occasion of Kapitza’s long-awaited visit to Cambridge as he came back for the first time following his detention in the Soviet Union. The presenters returned to a topic they could not fully master thirty years before: Kapitza and Dirac discussed the scattering of electrons by standing light waves.

But we get ahead of ourselves with the Kapitza Club story, and now we return to Kapitza’s early Cambridge days. In 1923, Kapitza defended his doctor of philosophy dissertation. He investigated extremely strong magnetic fields, which was a new direction at the Cavendish Laboratory. Rutherford made Kapitza the assistant director for research on magnetism of the Cavendish Laboratory. Kapitza’s next recognition came when he was elected member of the most prestigious Trinity College of Cambridge University.

Rutherford supported Kapitza’s ambitious project; he helped it by encouraging funding agencies to finance the construction and development of new and costly equipment. Rutherford’s support was all the more remarkable because Kapitza’s research was a sharp departure from the Cavendish tradition of using simple means and building rudimentary experiments, the “sealing wax and string” approach to physics. Kapitza demanded expensive equipment, showed his familiarity with workshop design, and was capable of producing proper drawings for construction. He was both a physicist and an engineer. To facilitate his project, a Russian technician joined him from home. A huge generator was built for Kapitza’s experiments by the company Metropolitan-Vickers of Manchester. The new magnetic laboratory of the Cavendish lab was opened in 1926 in the presence of the chancellor of Cambridge University, the former prime minister Arthur Balfour.

In the same year, Kapitza made his first visit back to the Soviet Union since his departure in 1921. Those visits then became an annual feature in his life. He kept up his interactions with his colleagues back home, discussed their research problems with them, and gave lectures. He traveled in response to official invitations issued by high-level Soviet politicians, such as Lev Trotsky and Lev Kamenev. Both Trotsky and Kamenev would eventually become victims of Stalin’s terror in his power struggle for the supreme leadership of the Soviet Union.5 In addition to the formal invitations, Kapitza always requested and was given an official letter guaranteeing him that he would be permitted return to England at the close of his visit.

Kapitza spent some time in Paris during his Cambridge years, and there he utilized his skills in playing chess. There were many cafés in Paris at the time where chess was played for stakes. When Kapitza first appeared at a particular café, he pretended to be a poor amateur. In the end he would usually win.⁶ In Paris, Kapitza met academician A. N. Krylov, a former shipbuilding engineer and government official in czarist Russia. He was now co-heading the academic delegation whose members included Kapitza. Krylov’s family had immigrated to Paris from Russia after the revolution. Kapitza was smitten by Krylov’s daughter, Anna Alekseevna, and in 1927 they married. They had two sons; Sergei, born in 1928, became a physicist, and Andrei, born in 1931, became a geographer (in spite of his father’s wish), and was immensely successful.

For the entire duration of his stay in England Kapitza remained a Soviet citizen, and his wife received Soviet citizenship upon their marriage. In 1929, Kapitza was elected both Fellow of the Royal Society (London) as a Soviet citizen and also a corresponding member of the Soviet Academy of Sciences. He was looking forward to a bright career based on his very special status as a Soviet citizen and a leader in British science. He made quiet inquiries whether a foreign national might become an English lord. The thought was bizarre, but when in 1931 Rutherford became Lord Rutherford, it no longer seemed so far-fetched.

The wealthy chemical industrialist Ludwig Mond left a large sum of money to the Royal Society. Fifteen thousand pounds sterling of the bequest went to subsidize a new magnetic laboratory at the Cavendish Laboratory. It was named Mond Laboratory. Kapitza was appointed its director. The Mond Laboratory was opened on February 3, 1933. Again, the chancellor of Cambridge University, Stanley Baldwin, another former prime minister and still the leader of the Conservative Party, opened the new laboratory. Kapitza chatted effortlessly with the esteemed guest and at one point said to the politician Baldwin, “You can believe me. I’m not a politician.”7

The dignitaries present included not only politicians and the director of the Cavendish, Ernest Rutherford, but also Rutherford’s former mentor J. J. Thomson. But for Kapitza, Rutherford was by far the most important of all those present. He coined a nickname for Rutherford, “Crocodile.” According to Kapitza, “In Russia the crocodile is the symbol for the father of the family and is also regarded with awe and admiration because it has a stiff neck and cannot turn back. It goes straight forward with gaping jaws—like science, like Rutherford.”⁸ The exterior of the Mond Laboratory showed a big crocodile in relief, and the key to the new laboratory had a handle shaped like a crocodile. Both were created by Kapitza’s friend, the sculptor Eric Gill. Rutherford knew his nickname and did not mind it.

Years later, Kapitza himself also acquired a nickname, “Centaur,” but it is not clear whether he liked it. It was coined by the outstanding physicist Aleksandr Shalnikov, one of the charter members of Kapitza’s Institute of Physical Problems in Moscow. Once Shalnikov was introducing a visitor to Kapitza who was shocked by Kapitza’s rudeness toward his subordinates. The visitor asked Shalnikov whether the director was a human or a beast. Shalnikov’s spontaneous response was that Kapitza was a centaur, and the name stuck.⁹

The apparatus in the Mond Laboratory was large and required special physical arrangements. Kapitza built a flywheel, which stored an enormous amount of mechanical energy. This energy was then released into a small wire coil, which exploded. This happened on a time scale of a fraction of a second. The explosion caused a strong mechanical shock that would disturb the sensitive recording instruments monitoring the experiment. This is why the instruments were placed twenty meters away from the experiment and the seismic wave reached the instruments only with a delay after the explosion had happened. For this arrangement, the magnet hall had to be long; it became a convenient gathering place for all who worked at the laboratory. The small rooms for the researchers opened from the magnet hall on either side of the hall.

David Shoenberg was among the students of the Mond Laboratory. He was to be Kapitza’s last student in Cambridge. Shoenberg’s roots were in Russia, so he had sympathy for Kapitza’s heavily accented English. It was not only the Russian accent and sentence construction that at times made Kapitza difficult to understand. His stories and jokes reflected his Russian background, and not everyone grasped easily what he wanted to say. But he had a appealing personality and when his jokes were not understood, his infectious laughter still made his listeners laugh. He was unorthodox in his approach in his lectures. His principle was that letting the students leave the lectures with contradictory ideas would stimulate their thinking. In his popularizing talks, which he gave frequently to scientific societies, he aimed to have 95 percent of his audience understand 5 percent of what he said; and 5 percent understanding 95 percent.10

J. J. Thomson and Ernest Rutherford after the inauguration of the Mond Laboratory in Cambridge.

Source: Photograph by and courtesy of the late David Shoenberg.

Crocodile carved into the façade of the Mond Laboratory.

Source: Photograph by and courtesy of the author.

Kapitza gave Shoenberg a research project in which he had to measure the changes in the size of a bismuth crystal in a strong magnetic field.11 The phenomenon is called the “magneto-striction of bismuth.” Kapitza himself had measured the change in the length of a bismuth crystal, but could only determine the change along the direction of the magnetic field. Shoenberg’s task was to measure the change in the direction perpendicular to the magnetic field. The changes in the crystal lengths are very small, and Shoenberg had to develop very delicate methods for their determination. Several times during the project Shoenberg was ready to give up, but Kapitza always came up with new suggestions about how to continue. He was full of ideas; many proved useless, but there were invariably some that moved the project along. There are scientists like Kapitza—and Edward Teller and George Gamow were in this category—who are full of ideas. They don’t mind pronouncing them even though most of them are worthless, because the few that are valid may be revolutionary. Other scientists—Enrico Fermi and Linus Pauling come to mind—were also full of ideas, but they did not like to make their suggestions out loud before sifting through them and discarding the worthless ones themselves.

Shoenberg learned a lot of physics from his interactions with Kapitza, and he got to know better his mentor’s human qualities. He got a taste of Kapitza’s temper in the course of this work. When Shoenberg collected all the experimental data, he tried to fit them to the scheme Kapitza had worked out. However Shoenberg tried, the data did not appear consistent with the scheme, but when he slightly modified it, everything fit in perfectly. He told Kapitza about his results, pointing out that Kapitza had made a mistake. His mentor’s reaction was “surprise and dismay, he [Kapitza] flew into a rage and said, ‘How dare you say such a thing to your teacher? Go and talk to [Paul] Dirac. He checked my calculations and Dirac never makes a mistake.’”12 Shoenberg did talk to Dirac. It turned out that Kapitza had given him erroneous information about the symmetry of the bismuth crystal, and this had caused the problem. With the correct symmetry, the scheme worked fine. This experience notwithstanding, Shoenberg was so attached to Kapitza that he spent some time with him in Moscow “when Kapitza was building his new institute. He behaved somewhat autocratically in Moscow too and, though his staff respected him, they were a bit afraid of him.”¹³

In spring 1934, still in Cambridge, Kapitza succeeded in the liquefaction of helium using an original apparatus of his own creation. He did a lot of work together with John Cockcroft, a pioneer nuclear physicist and future Nobel laureate, who was one of Kapitza’s few doctoral students. Kapitza’s revolutionary helium liquefier served as the foundation for a mass-produced helium liquefier to be developed in and marketed from the United States. But in England, Kapitza’s was not the first liquid helium; Oxford University had liquefied it first, relying on a small machine from Germany built by Francis Simon. When the Nazis came to power in Germany, the Jewish Simon found refuge in Oxford.

On September 1, 1934, Kapitza arrived in the Soviet Union for his usual visit. This time, he had failed to secure the written Soviet permission to leave the country upon the completion of the visit. At this point, he felt it was embarrassing to continue the practice although George Gamow had urged him to get the guarantee. Kapitza told Gamow that a high Soviet official had explained to him: “You must see by now that nobody wants to hold you here by force. And it is somewhat beneath our dignity to give such assurances to the stuffy British Lord [Rutherford], who does not understand these matters.”¹⁴ Gamow had experienced great frustration when he was repeatedly refused permission for foreign travel. When in 1933 he was finally permitted to attend the Solvay meeting of physicists in Brussels, he stayed out of the Soviet Union for good.

During Kapitza’s 1934 visit, he was told that he would not be permitted to return to England. This was a rude resolution of the relationship between Kapitza and the Soviet state. In 1929, when he corresponded with Kamenev, then the member of the top Soviet leadership responsible for science, they seemed to be equal negotiating partners. Kamenev would have liked Kapitza to return to the Soviet Union full time, and if not full time, at least to spend considerable lengths of time annually in his homeland. Kapitza presented certain conditions and excluded the possibility of predetermined lengths of time. But he was willing to help Soviet science: “I have been following with great interest and satisfaction the tremendous development of scientific research work in Russia and am very glad that I now have the opportunity of helping.”15

It was Stalin who decided to retain Kapitza.¹⁶ On September 21, 1934, the dictator wrote: “Kapitza may not be arrested officially, but he must be retained in the Soviet Union and not let return to England on the basis of the law about non-returning persons. This will be a sort of house arrest. After that, we will see.”¹⁷ A few days later, a deputy prime minister, Valery Mezhlauk, informed Kapitza that he could not leave, that an institute would be built for him in Moscow at the location of his choice, that he could select his co-workers, that his experimental apparatus would be purchased for him from abroad, and that he would be given a spacious home in downtown Moscow.

Gamow’s defection in 1933 had been a blow to the Soviet leadership; yet I am not suggesting that Kapitza’s retention was its direct consequence, although its impact cannot be excluded. In November 1933, Kapitza wrote to Niels Bohr, “It is better for every man to work in the country and under the conditions which he likes most, and this is why I think it would be much better for Gamow to work abroad.”¹⁸ Kapitza senses the possible consequences of Gamow’s action on others in the Soviet Union when he mentions “that [Gamow’s defection] will make it extremely difficult for young Russian physicists who wish to study abroad to get permission.”¹⁹

The bitter irony of the world situation did not escape Kapitza. Kapitza was a prisoner in his own country, communist Russia, whereas great scientists of similar caliber were being forced out of Nazi Germany. When the Jewish German physicist Max Born was looking for a refuge, he shared his dilemma with Kapitza. In response, the Soviet physicist wrote to him: “You are an unlucky man, everybody wants you and the choice is so great that you cannot make up your mind. Maybe I am somewhat luckier than you are, as I have no choice.”²⁰ But then Kapitza expresses an unexpected but logical idea; he urges Born to join him in Moscow and build his new scientific home there. Born and his wife had planned a brief exploratory visit to Moscow when he received an attractive offer from Edinburgh, which he accepted at once., Born noted in his memoirs that in light of the further developments in the Soviet Union, “accepting Kapitza’s offer would have been a catastrophe.”²¹

Petr Kapitza’s group in the mid-1930s in the courtyard of the Institute for Physical Problems in Moscow. Kapitza is in the middle, David Shoenberg is to his left. Aleksandr Shalnikov is at the extreme left.

Source: Courtesy of the late David Shoenberg.

It is easy to imagine Kapitza’s state of mind when he understood that he would not be let out from the Soviet Union, would not be able to continue his life in Cambridge, and would not even be let to go there for a short visit to finish his ongoing projects. But his desperation did not prevent him starting to plan for his science in Moscow. At the end of 1934 it was decided to build his institute in one of the choicest locations in Moscow, on a hill overlooking the Moscow River and the city. Its name was to be Institute of Physical Problems (Institut Fizicheskikh Problem [IFP]) and Kapitza was appointed its director. Today, it is the P. L. Kapitza Institute of Physical Problems of the Russian Academy of Sciences. The naming of the institute had its own peculiar story. The president of the Soviet Academy of Sciences, Sergei Vavilov, died in 1951. At that time Kapitza was in exile from his institute. Vavilov was a physicist, and it was decided to name the IFP after him. For years, there was a tablet at the entrance of the institute, reading something like this:

Awarded the Order of Red Banner of Labor
S. V. Vavilov
Institute of Physical Problems

The Order of Red Banner of Labor indicated there was for the Institute rather than for an individual. When Kapitza was reinstated as director in 1954, he ordered the tablet changed. He diminished the letters referring to Vavilov and enlarged the letters referring to the institute to look something like this:

Awarded the Order of Red Banner of Labor
S. V. Vavilov
INSTITUTE OF PHYSICAL PROBLEMS

It was after Kapitza had died that the Presidium of the Soviet Academy of Sciences changed the name to P. L. Kapitza Institute of Physical Problems. They found another institute to name after Sergei Vavilov.22

There has been a lot of speculation about why Stalin forced Kapitza to stay in the Soviet Union. Most probably, it was a confluence of several reasons. We single out one of them that might also bring us closer to understanding Kapitza’s personality. Rutherford did everything possible to secure freedom for his favorite pupil, but he thought that the explanation for Kapitza’s retention may have been due his “love of the limelight.”²³ On one occasion, Kapitza told a group of Soviet engineers that “he himself would be able to alter the whole face of electrical engineering in his lifetime.”²⁴ The Soviet leadership—Stalin himself—may have well been intrigued by this statement and seen in it tremendous strategic importance both for the economy and defense. Lenin used to stress the supreme importance of electrification for Soviet success; his slogan was: “Communism is Soviet power plus the electrification of the entire country.”²⁵

In 1935, at Rutherford’s suggestion, Cambridge University decided to sell the scientific equipment of the Mond Laboratory to the Soviet Union. This gesture greatly facilitated Kapitza’s research efforts, but Kapitza would not be allowed to travel to England for the next thirty-two years. His wife, however, could return to England to collect their two sons and belongings and in January 1936 she and their two sons came back to the Soviet Union. The world of science was learning about Kapitza’s detention only many months after it happened. Kapitza knew that if he was to have any hope of reversing the decision of the Soviet leadership, any actions of his supporters should be taken quietly rather than in the limelight. However, Stalin was determined to keep him.

Progress was very slow in developing the right conditions in Moscow to enable Kapitza to continue his scientific activities. He understood that the Science Academy was powerless in this matter, and he started corresponding with top Soviet leaders. Starting from 1934, he wrote well over two hundred letters to Stalin, Molotov, and Malenkov. He bombarded the subsequent Soviet leaders with his letters, including Khrushchev, Bulganin, Brezhnev, and Andropov among them. Most of his letters were not just brief notes, but substantial treatises. It was under Stalin that he wrote his most important letters. Some were heroic attempts to gain the freedom of arrested scientists. Others were about the state of Soviet science, the situation of scientists, science education, and other topics on which Kapitza felt his advice might be useful. Sadly, however, there were also letters in which he denounced other scientists and technologists when he had disagreements with them. This was part of his controversial character.26

In his long letter of December 1, 1935, to Stalin, he complains about how sordidly he was treated not only by being forced to stay in the Soviet Union but afterward.²⁷ Once it was decided that he could not leave, and once he committed himself to continue his work and build up his research in Moscow, he should have been assisted in his efforts. Instead, he was being treated as a suspicious stranger, at best. He found it unreasonable that he would not be given close to ideal conditions for his work if keeping him was considered important. There is sad irony in the fact that the only person Kapitza singled out in his letter as a positive example was Karl Bauman, the party leader responsible for science, who was arrested in 1937 and perished in prison.

By the summer of 1936, the building of Kapitza’s new institute was completed at about the same time most of the equipment from the Mond Laboratory arrived. Two technicians of the Mond were each given a one year leave to help Kapitza’s associates assemble and learn how to operate the apparatus. The Soviet government paid for the equipment, but, of course, the Cavendish scientists working on the transfer, including Rutherford, were not compensated for their lost research activities. They did not complain, once again demonstrating how much they felt that Kapitza was one of them and were willing to help him in whatever way they could.

From summer 1936, Kapitza settled into his Soviet period, which showed continuity for the rest of his life (in spite of the interruption of his internal exile between 1946 and 1954). One of his characteristic traits was his fearlessness in facing the authorities. He waged protests when he became aware of injustices suffered by fellow scientists. Alas, such injustices were so numerous that he could raise his voice only in selected cases. It needs to be stressed, however, that Kapitza was a Russian patriot and a Soviet patriot, and appreciated what the Soviet regime was trying to achieve in science. He understood the characteristics of Stalin’s autocratic system, perhaps because he was also inclined to build an autocratic order around himself. Stalin may have felt some respect for Kapitza’s strong personality. Kapitza wrote numerous letters to Stalin, whereas the dictator sent him a total of two brief letters. In one of the two, dated April 4, 1946, Stalin referred to Kapitza’s letters: “There is much that is instructive in them and I should like to meet you at some time to have a chat.”²⁸ However, they never met.

Kapitza had hardly started his Soviet life when he already felt obliged to wage a protest in defense of a fellow scientist. In 1936, attacks against a noted mathematician, Nikolai Luzin, appeared in a series of anonymous articles in the Communist Party’s central newspaper, Pravda. These included accusations that Luzin followed ideologies alien to the Soviet order, stole his students’ results, published poor papers in Soviet journals, and published his best results in foreign periodicals. Luzin was a full member of the Soviet Academy of Sciences, and an Academy commission ominously endorsed the accusations. It was expected that he would be expelled from the Academy, arrested, and would perish in incarceration. Kapitza learned about the Pravda articles while on vacation in the countryside, and immediately wrote a long letter of protest in defense of Luzin. He addressed his letter to the chairman of the Council of People’s Commissars (Council of Ministers), Vyacheslav Molotov.29

Kapitza did not deal with the accusations against Luzin because he was not familiar with the details of the story. He explained that preventing the publication of poor articles was the responsibility of the journal editors, and that it was in the interests of both Luzin and the reputation of all Soviet scientists to publish their best articles in international journals. His main point was that Luzin’s value should be judged by the level of his work. He added that the Soviet Union had to rely on many such scientists who were not necessarily friendly toward the Soviet order. Kapitza noted: “We have not so far succeeded in producing new scientists from among our young people. I explain this by a very wrong attitude on your part towards science—much too narrowly utilitarian and insufficiently supportive” (italics added).³⁰ Further, Kapitza writes, “People like Luzin, who differ from us ideologically …”³¹ This is very curious, not in that he separates himself from Luzin but in that he identifies himself with Molotov. The outcome of the case was that Luzin was never arrested and was not even expelled from the Academy of Sciences. The attacks against him stopped.

Soon after Kapitza’s institute had begun its operations, it started yielding seminal results some of which could be applied directly for practical purposes. He and his associates developed a technology to liquefy air, produce liquid oxygen and nitrogen, and extract inert gases from air. Simultaneously, fundamental science was cultivated, and the free flow of scientific ideas and experience encouraged. Kapitza’s seminars gained a new life at his institute. His huge office provided plenty of space for these meetings. The war-time evacuation, and then Kapitza’s absence from the Institute between 1946 and 1954, disrupted the organization of the seminar, but in the second half of the 1950s, it outgrew his office. In addition to the associates of the institute, even more attended from the outside. On February 8, 1956, a milestone event took place in the Kapitza seminars. The biologist N. V. Timofeev-Resovskii and the physicist Igor Tamm talked about modern genetics in open defiance of “official” Soviet biology as determined by the unscientific czar of Soviet biology, Trofim Lysenko. This was a brave and significant step in turning around the tragic history of this most important science in the Soviet Union.

Once again, we get ahead of ourselves in presenting the Kapitza seminars. So now we return to the second half of the 1930s. A brilliant and internationally renowned theoretical physicist, Vladimir Fock, was arrested on February 11, 1937, in Leningrad. Fock had been a professor at the university since 1932. He was very young when he generalized Schrödinger’s equation for magnetic fields and for the relativistic case involving charged particles moving in magnetic fields. His methodology of calculating the structure and energy of polyatomic molecules, combined with the American Douglas Hartree’s approach, generally known as the Hartree-Fock method, is still being used in quantum chemical calculations.

As soon as Kapitza learned about Fock’s arrest, he wrote a letter to Stalin. He lamented the rough treatment of scientists, which would interfere with their ability to work, just as rough treatment of a machine would unfavorably impact the quality of its product. He compared Fock’s fate to how Einstein was treated by Germany.32 He referred to Fock as the most outstanding theoretical physicist in the Soviet Union. He maintained that his arrest must have been a mistake and that the accusations—that Fock had engaged in sabotage by knowingly providing the wrong formula for the evaluation of electrical exploration in geological work—were impossible. Within days, Fock was freed from captivity.³³

The year 1937 brought sad news for Kapitza: on October 19, Rutherford died. Kapitza wrote to Niels Bohr, “All these years I lived with the hope that I shall see him again and now this hope is gone…. I loved Rutherford…. I learned a great deal from Rutherford—not physics but how to do physics.”³⁴

Kapitza found a lot of joy in his work. He prepared his report for Nature and for the Russian journal Doklady Akademii Nauk (Proceedings of the Academy of Sciences) about the discovery of superfluidity of liquid helium. He was also the one who introduced the term “superfluid.”³⁵ The discoveries on the transport properties of liquid helium would bring two Nobel Prizes in Physics for the Institute for Physical Problems. The first was to Landau in 1962 (see chapter 5) for his theoretical interpretation of Kapitza’s experimental discovery. The second was for Kapitza in 1978. The motivation for Kapitza’s award was quite general, referring to his basic inventions and discoveries in low-temperature physics. Kapitza referred to the slowness of his award in his Nobel lecture, pointing out that he had left the field in which he received the Nobel Prize thirty years earlier. He delivered his Nobel address on plasma and controlled thermonuclear reactions, a project that recently occupied his mind.³⁶

The key elements of Kapitza’s discovery, superfluidity and helium, were missing from the citation of Kapitza’s Nobel Prize. This was because Kapitza’s discovery of the superfluidity of liquid helium was not unique. At about the time of Kapitza’s involvement, two physicists in Cambridge obtained similar results independently. There was a slight priority in Kapitza’s favor according to the dates of submission of the respective manuscripts, Kapitza’s on December 3, and Allen and Misener’s on December 22, both in 1937. The two papers appeared back to back in the same issue of Nature in early 1938.37 Soon Kapitza made another experimental discovery. He noticed that when heat flew from a solid surface into helium, there was a temperature jump at the surface. It was later called the Kapitza Jump, and it took a long time for the theoreticians to explain it.

The unprecedented terror of 1937–1938 produced an incident that struck especially close to home. The exceptionally gifted Lev Landau was arrested by the secret police, Narodnii Komissariat Vnutrennikh Del (People’s Commissariat of Internal Affairs [NKVD]), on April 28, 1938. Landau was in charge of theoretical physics at Kapitza’s institute.^† Again, Kapitza took immediate action, and he turned to Stalin. Landau was freed exactly one year later, in 1939, under Kapitza’s supervision. The story of Landau’s incarceration has been told and retold repeatedly. There have been various versions and its details have been marred by gossip and the lack of hard evidence. Boris Gorobets, a scientist and author of a Landau trilogy, has made a thorough analysis of all available information and separated facts from myths; here we follow his recent account.³⁸

Landau had participated in the production of an anti-Stalin leaflet, which was highly critical of the Soviet dictator, labeling him and his regime fascist. This is a fact. Landau’s arrest was most likely provoked by his involvement with this leaflet. Not that valid reasons were needed for an arrest in 1937–1938, but in this case, there was one. By this time Landau had developed strong anti-Stalin sentiments. When, years later, Landau was asked about the accusations against him, he kept quiet about the anti-Stalin leaflet and talked about the accusation that he was a German spy. This would not have been a very sophisticated accusation, but NKVD actions were hardly ever based on a sophisticated rationale. There might have been yet another “justification” for the authorities to take action against Landau. When he was still in Kharkov, and the question had arisen whether or not the Ukrainian Institute of Physical Technology (Ukrainskii Fiziko-tekhnicheskii Institut [UFTI]) should shift its activities from basic research to defense-related work, Landau was against the change.

Landau’s genius was badly needed in Soviet theoretical physics, in general, and to find the interpretation for Kapitza’s discovery of the superfluidity of helium, in particular. When Kapitza, following Landau’s arrest, turned to Stalin, he stated that if Landau committed a crime—and he could have not been sure that he had not—he should be punished, but he doubted it very much. There was no response from Stalin. Almost a year later, in a letter to Molotov, Kapitza even brought up the possibility of sending Landau to a special camp for incarcerated scientists and engineers; he believed it to be of the utmost importance to spare Landau’s life. He argued that Landau’s brain should be utilized for the benefit of the socialist fatherland.

Landau’s arrest happened toward the concluding phase of the Terror of 1937–1938; in fall 1938, the Terror was subsiding. The new interior minister, Lavrentii Beria, who replaced Nikolai Ezhov, approached the problem in a more rational way than his predecessor. For example, he wanted the camps to become economically viable; he knew that starving prisoners could not produce. About three hundred thousand people were freed, one-third of all prisoners arrested in the years 1937 and 1938.39

For Landau, things were developing painfully slowly. However, after Kapitza wrote to Molotov in April 1939, Kapitza was first invited to see Molotov and then for a visit to the infamous headquarters of the NKVD—Lubyanka. He was received by two high-positioned officials of the Ministry. Again, it is a fact that Kapitza spent hours in the company of these officials. As to what they talked about, various versions have floated around. However, a few days following Kapitza’s visit, Landau was freed. Landau learned only many years later that he was freed on the condition that he would remain under Kapitza’s supervision.

Kapitza must have learned about the anti-Stalin leaflet during his visit to the NKVD. If he did, it must have shocked him, but he must have instantaneously regrouped and continued his mission. He understood that the leaflet story was different from the false accusations, and that regardless of the easing up of the terror, Landau’s life was still in great danger. Kapitza must have found the winning arguments to convince the NKVD officials or, rather, their bosses Beria and, ultimately, Stalin. He must have argued that Landau was irreplaceable and badly needed for Soviet science. Beria could ignore political considerations if economic or defense benefits were at stake, and it seems very probable that Kapitza’s arguments had an impact on him. Still, at this time, Landau’s value was not yet that high in Beria’s eyes—years later it would grow tremendously within the framework of the nuclear weapons program. Mere usefulness would not have sufficed at this point; a number of other people were being incarcerated who might have been no less useful to the economy and defense than Landau. I mention two of the brightest names, who later entered the top tier of the Soviet scientific-technological elite: Sergei Korolev of rocket technology and the airplane designer Andrei Tupolev. The big difference between their situation and Landau’s seems to have been the existence of Landau’s protector, Kapitza. Stalin respected him and Kapitza had not yet alienated Beria at this point.

It would have been difficult even for Beria to deal with an accusation of a crime directed against Stalin personally, shutting Stalin out of it. The utterly implausible accusation of Landau’s being a German spy would fit all parties although for different reasons. For Kapitza and Landau, an implausible accusation was preferable to one that revealed his opposition to the beloved leader. As for Stalin, he must have found it attractive to have an accused spy promising good behavior under Kapitza’s tutelage. The alternative would have demonstrated that Landau, a world-renowned scientist and the most gifted person of his generation in science, considered him a fascist and was willing to die fighting against him.

This is also only a probable scenario, but none of the other versions circulating in various memoirs have documentation to support them either. This version is a reasonable explanation for why the accusation that Landau spied for Germany has survived for so long even though it is a myth. It is not a myth, though, that Kapitza took a strong stand in Landau’s defense under circumstances in which such bravery was almost unthinkable.

On June 22, 1941, Germany attacked the Soviet Union and made quick initial advances, soon threatening Moscow. Kapitza’s institute was evacuated to Kazan along other scientific institutions. For the duration of the war, Kapitza served as member of the Scientific-Technological Council at the State Defense Committee (headed by Stalin). During the war, a portion of liquid oxygen important for the defense industry was produced according to Kapitza’s methods (most of it, though, continued to be produced by the classical German technology). Kapitza was appointed to be in charge of the main oxygen authority.

There were other recognitions. In 1939, Kapitza was elected full member of the Soviet Academy of Sciences. He received two Stalin Prizes, one each in 1941 and 1943. In 1945, Kapitza was awarded his first Hero of Socialist Labor star for his contribution to the production of liquid oxygen. In 1974, he would receive a second one on the occasion of his eightieth birthday. He cherished these two golden stars the most and would wear them on December 10, 1978, on his formal dress in Stockholm, at the Nobel Prize award ceremony.

In August 1945, the State Defense Committee created a special subcommittee for the development of the atomic bomb. Igor Kurchatov and Kapitza were its only scientist members. For some time, things developed nicely for Kapitza; he had his own institute, achieved successes both in fundamental and applied science, and was a revered member of Soviet society. This idyllic situation, however, was not to last. He soon clashed with the all-powerful Beria.

From the start of Kapitza’s brief involvement in the Soviet atomic project, he felt out of place. He did not like being merely one of the crowd in a nonleadership position. Neither did he like to participate in solving routine tasks where he could not let his imagination fly. The Soviet nuclear weapons project was like that during the creation of the first Soviet atomic bomb, which was built as a faithful copy of the American one. Nuclear physics was not Kapitza’s field; there were many scientists in the project whose expertise was more germane in this undertaking. Beria, who was in charge of the project, looked down on scientists. He appreciated them only as long as he needed them.

Kapitza had no knowledge about the role of intelligence in building the first Soviet atomic bombs. Only two scientists, Kurchatov and Yulii Khariton, knew about the information arriving from the United States through espionage. They could not give away the source of their ideas, and it was made to appear merely a lucky coincidence that Kurchatov always came up with the solution for the next step that would fit the project of emulating the Americans. The main characteristics of the Manhattan Project were not classified, and to the surprise of the Soviet authorities, the Americans had published a whole volume filled with information, the so-called Smyth Report.40 However, the technical details still had to come from espionage, and they proved to be absolutely correct.

Kapitza noted in his long letter to Stalin of November 25, 1945, that the person in charge of the project, Beria, was like a conductor of an orchestra. He had the conductor’s baton in his hand, and he waved it, but he did not understand the score.⁴¹ Kapitza could not have known that Beria did possess the perfect (American) score, which he did not have to understand; he only had to make sure that the Soviet scientists faithfully followed it. Kapitza’s constant nagging that the scientists should come up with original approaches must have annoyed Beria, creating a situation in which Kapitza no longer represented value for the project Beria cared about. On top of this, Kapitza kept complaining about Beria to Stalin. Kapitza was taking a tremendous risk, because for all he knew, his own life might have been in danger. Kapitza acted, though, as a shrewd politician when he added a post script to his letter of November 25 asking Stalin to show his letter to Beria, because Kapitza considered the letter “not a denunciation but a useful criticism.”⁴² Kapitza wanted to be excused from the special committee, and by Stalin’s direct order of December 21, 1945, his request was granted. Finally, by another direct order of August 17, 1946, Stalin let Beria remove Kapitza from all his positions by direct order, but he did not touch his life.

Kapitza’s removal from the Oxygen Authority, responsible for the production of oxygen for industry, was the final step in a long-standing bitter struggle between him and those technologists who favored the classical methods of producing liquid oxygen. The way Kapitza fought this battle was not befitting a great scientist in that he resorted to accusations and could not rid himself of bias toward the technology that he had discovered.

His removal from the Institute of Physical Problems was especially painful. It seemed to be a payback from Beria, but the real reason may have been more mundane. Kurchatov and the atomic bomb program badly needed Landau and his theory group of the IFP, and it was doubtful that Kapitza would have let a substantial section of his small institute be removed from his jurisdiction. For Beria, and for Stalin, the simplest solution appeared to be taking the whole IFP away from Kapitza.

The period from the end of the war, and especially from 1948 to Stalin’s death in 1953, was another time of intensified repression in the Soviet Union. That included increasingly overt anti-Semitism. Kapitza was sensitive to the occurrence of any kind of anti-Semitism. His ancestors were of Russian and Polish stock. He subscribed to the tenet that anti-Semitism was a disease, and he would not tolerate any intolerance. In 1933, while he was still in Cambridge, Jewish German scientists started coming to Great Britain as refugees, and in his letters to his mother, Kapitza wrote about their plight. He noted the large number of famous scientists among the refugees, but was concerned especially with the fate of the unknown young ones who had not yet had the opportunity to make their names in science. Kapitza assisted Paul Ehrenfest and Leo Szilard in trying to find employment for the refugees in Western Europe and the United States. Again, he was in complete accord with Rutherford, who in spite of being most apolitical, devoted himself to helping the refugees. Rutherford was the president of the newly formed Academic Assistance Council and remained in this position to the end of his life.

Back in the Soviet Union, Kapitza remained vigilant in opposing anti-Semitism. He was horrified by the genocide during World War II and was one of the speakers on August 24, 1941, at the anti-fascist meeting of representatives of the Jewish people. The speeches were broadcast all over the world. Kapitza stressed that state-sponsored anti-Semitism, as was taking place in Germany, flared up when a country was undergoing a period of deep crisis and reactionary time. Such state-sponsored anti-Semitism relied on the lowest instincts of the people. He also referred to the pogroms during czarist times. Kapitza’s speech and the whole anti-fascist movement must have been recalled with horror during the last years of Stalin’s life when Soviet anti-Semitism took on appalling intensity. First, in 1948, was the assassination of Solomon Mikhoels, disguised as a road accident, which was followed, in 1952, by the execution of the rest of the leaders of the Jewish Anti-Fascist Committee and many other actions in between and after.

When Kapitza was exiled from his institute, he moved to his summer home in Nikolina Gora, one of the most exclusive suburbs of Moscow. A lesser scientist might have been lost under these circumstances, but not Kapitza. He ingeniously found a way to continue research in physics, and even to continue his letter writing to the high authorities. In Nikolina Gora, he formed a unique laboratory, which he called the Hut of Physical Problems by way of analogy with the Institute of Physical Problems. Lev Landau and Evgenii Lifshits were regular visitors. Eventually, the president of the Academy of Sciences and the new director of the Institute of Physical Problems allowed a technician to help Kapitza with his experiments.

Another occupation Kapitza found for himself was involvement with the preparation of young physicists. In 1947, a new Faculty of Physical Technology at Moscow State University came to life, which in 1951 became the exceptionally strong Moscow Institute of Physical Technology. Kapitza recognized the importance of educating well-trained physicists for the Soviet nuclear industry and elsewhere, and became one of its founding members. He was appointed chairman of the Department of General Physics, and he and Landau alternated giving the course of general physics ensuring the exceptionally high level of this course. The students crowded in for these lectures; the lucky ones were those who could attend during either of the two academic years 1947/48 and 1948/49 while Kapitza remained in this position.

Toward the end of 1949, huge festivities were organized to honor Stalin’s seventieth birthday, December 21. Kapitza did not attend them, and the university responded by stopping him from teaching. The pro-rector wrote to him in a letter that “it is not possible to entrust the education of our scientific youth to someone who sets himself against the whole of our people in such a demonstrative manner.”43 He was officially dismissed from his job a few weeks later by the rector of the university, A. N. Nesmeyanov. The justification for dismissal was that Kapitza was no longer involved with teaching.

By this time Kapitza had stopped writing letters to Stalin, and on one occasion the dictator instructed Georgii Malenkov to call Kapitza and ask him why.⁴⁴ Stopping his letter writing and staying away from the festivities were the only actions Kapitza could take to express his resistance. Of course, Stalin might have ignored the slight, but he was so unused to even the minutest sign of resistance that he could not; thereby he helped, however involuntarily, Kapitza’s action to take on real significance. Alas, the controversy between Stalin and Kapitza was not between equals as far as their potential to hurt the other was concerned. We have seen that Stalin’s reaction to the snubbing by Kapitza was to have him dismissed from his teaching post. Curiously though, there was still someone, somewhere who tried to provide some solace: On June 1, 1950, the outstanding crystallographer Aleksey Shubnikov invited Kapitza to be a consultant at the Institute of Crystallography of the Soviet Academy of Sciences.⁴⁵ Incidentally, the Soviet Union was hermetically isolated from the external world in these years. Some outside organs watching the Soviet nuclear program for a while assumed that Kapitza’s disappearance from view must mean that he was participating in the classified project. Misconceptions die hard; even in 1968, an article in the New York Times characterized Kapitza as “Stalin’s chief scientific adviser.”⁴⁶

One of Kapitza’s research topics in exile was the development of strong microwave beams. They were supposed to be so powerful that Kapitza considered their possible military use. The function of these high-energy beams would be to annihilate incoming attackers (this was reminiscent of President Reagan’s SDI). Kapitza wrote in his letter of June 25, 1950, to Malenkov:⁴⁷

During the war I was already thinking a lot about methods of defence against bombing raids behind the lines [that would be] more effective than anti-aircraft fire or just crawling into bolt holes. Now that atomic bombs, jet aircraft and missiles have got into the arsenals, the question has assumed vastly greater importance. During the last four years I have devoted all my basic skills to the solution of this problem and I think I have now solved that part of the problem to which a scientist can contribute. The idea for the best possible method of protection is not new. It consists in creating a well-directed high-energy beam of such intensity that it would destroy practically instantaneously any object it struck. After two years work I have found a novel solution to this problem and, moreover, I have found that there are no fundamental obstacles in the way of realizing beams of the required intensity.

Kapitza soon renewed his letter writing to Stalin, and in a letter dated November 22, 1950, he mentioned this idea again and complained about the absence of assistance, without which he could not further develop this strategically important project. Kapitza could not be sure whether his letters reached Stalin, but in a phone call from Malenkov he learned that Stalin did indeed read his letters. By the way, Kapitza had to go to a location that had a telephone to receive Malenkov’s call because his summer house did not have one.

On March 5, 1953, Stalin died, and on June 26, Beria was arrested, soon to be executed. On August 28, the Science Academy decided to create a new physical laboratory on the basis of Kapitza’s makeshift unit at his summer home. Finally, on January 28, 1954, Kapitza was reinstated as director of the Institute of Physical Problems, remaining in this position for the rest of his life. His research interest for the next decades remained the same as what had formed in his summer home: high-performance electronics and plasma physics.

When Nikita Khrushchev came to power Kapitza started a correspondence with him. Their relationship was a more two-way interaction than Kapitza’s had been with Stalin. A minor episode might illustrate Khrushchev’s style and subjective judgment and that Kapitza did not lose his ability to take a principled stand in a controversy. At a Kremlin reception Kapitza wore a Ukrainian shirt rather than the prescribed formal attire and Khrushchev made a critical remark pointing this out. Kapitza’s response was to inform Khrushchev that “surely diplomatic protocol recognizes national dress as appropriate for formal occasions.”48

Kapitza must have felt satisfaction when Beria fell, and he wanted Khrushchev to learn about his own problems with Beria. In 1955, he sent copies of letters to the Soviet leader in which he had complained to Stalin about the way Beria treated scientists.⁴⁹ In another letter Kapitza scolded the Soviet scientific establishment.⁵⁰ However, conditions looked different from the outside. In the period between the mid-1950s and the mid-1960s the American scientists looked with envy at some of the achievements of Soviet science. There were problems to be sure, and the successes did not penetrate deeply. But the state of science education in the Soviet Union was an example for many American scientists when they urged the allocation of greater resources to science and science education in the United States.

One of the most important changes in Kapitza’s life during its last two decades was that he was allowed to travel to the West, but this came only after Khrushchev’s fall. In his memoirs Khrushchev discussed the reasons that even after Stalin’s death Kapitza was not allowed to travel. It is incredible how erroneous and unsophisticated Khrushchev’s evaluation was: “On the one hand, in the world [Kapitza] is recognized as one of the most significant scientist-physicists; on the other hand this scientist did not give us the possibility of obtaining the atomic bomb before the United States, or even if not before, he did not assist us in creating the Soviet atomic bomb.”⁵¹ Khrushchev consulted the leading mathematician academician M. A. Lavrentiev about Kapitza’s trustworthiness. The Soviet leader was concerned that Kapitza might defect during visits to other countries or give away state secrets, even if unintentionally. Lavrentiev vouched for Kapitza’s trustworthiness. Nonetheless, Kapitza was not allowed to travel, which the deposed leader later regretted.52

Petr Kapitza at the right listening to the presentation by Igor Landau, Lev Landau’s son, at the Institute of Physical Problems in Moscow.

Source: Courtesy of Boris Gorobets, Moscow.

Petr Kapitza and Yulii Khariton.

Source: Courtesy of Alexey Semenov, Moscow.

Under subsequent leaders, Kapitza continued his letter writing. For example, he protested the practice of the Soviet censors of tearing out pages from publications. Sometimes whole articles in scientific journals and magazines were removed before they reached the libraries. Western scientific literature was scarce in the Soviet Union, but even those who had access to it could not be entrusted with some of the information it contained. When Kapitza received copies of the Italian translation of his book Experiment, Theory, Practice, the thirty-page preface had been torn out from each copy.53 The book was published by an Italian communist publisher and the preface was written by an Italian communist philosopher. Kapitza, in his letter of April 22, 1980, to Yurii V. Andropov, then chairman of the secret police, protested: “I decided to write to you about the article torn out of the translated edition of my book because this was done by officials who are responsible to you.”⁵⁴ By that time the secret police was called the Committee of State Security (Komitet Gosudarstvennoi Bezopasnosti [KGB]). Andropov responded that the KGB did not engage in such activity, and sent Kapitza a complete copy of the Italian edition, including the thirty-page preface.

Kapitza wrote to Andropov in defense of Soviet dissidents, too, including Sakharov; we have no information that the KGB chief would have been as accommodating in these cases as in the case of the Italian book. Incidentally, Kapitza tried repeatedly to intervene in Sakharov’s case. Sakharov did not know of his actions and lamented that Kapitza did not defend him during his exile in Gorky. Later, Sakharov learned of Kapitza’s actions.⁵⁵ Kapitza was an activist, but sometimes the absence of action spoke louder than his deeds. Thus, when in 1973, a letter was published in Pravda signed by forty fellow academicians condemning Sakharov’s “anti-Soviet” activities, Kapitza’s name was conspicuously missing.

Kapitza was a controversial individual, but he was an outstanding physicist and a brave fighter on behalf of his persecuted colleagues. Universal human values and Soviet-Russian patriotism together directed his actions while his demeanor was colored by autocratic attitude. He was a giant in a bygone era. C. P. Snow said of him: “If he hadn’t existed, the world would have been worse: that is an epitaph that most of us would like and don’t deserve.”⁵⁶