Paul Erenfest and Physics of Russia. Part One. Student and his teacher

The first sprouts of theoretical physics in Russia rose in St. Petersburg, where for five years, from 1907 to 1912, the outstanding physicist Paul Erenfest was conducted at home. According to Albert Einstein , a close friend of Erenfest: “ His greatness consisted in an extremely well -developed ability to capture the very essence of the theoretical concept and free the theory from its mathematical outfit so that the simple idea that underlies it with all its clarity. This ability allowed him to be an incomparable teacher. For the same reason, he was invited to scientific congresses, because he always introduced grace and clarity in discussions ”(Einstein, 1967, p. 191).

Yuri Borisovich Rummer believed that “ Erenfest was an absolutely wonderful person. It always seemed to me that in modern physics he plays about the same role as Belinsky in the history of Russian literature. He was considered a critic, Einstein was extremely carefully listening to his opinion, and, in addition, he was friends with everyone. Everyone loved him terribly ”(Rummer, 2013, p. 54–55).

Erenfest arrived in St. Petersburg in the fall of 1907, along with his wife Tatyana Alekseevna Afanasyeva , a teacher of mathematics in the highest female courses. They met in Gettingen, where Tatyana was an internship, and Paul listened to lectures at the university. Erenfest came to Germany from Vienna, where he began the study of physics under the leadership of the great Bolzman.

On the scientific sky of the late XIX - early XX centuries, when the stars of the plank , Einstein, Rutherford and Bora , the star Ludwig Bolzman, shone almost brighter than anyone else. He was interested in almost all areas of physicists and even some areas of mathematics, but his most significant contribution to science is associated with the use of statistical methods in the theory of ideal gases, with the study of irreversible processes and the statistical interpretation of the second beginning of thermodynamics. The so-called H-theorem Bolzman caused a strong shock in the scientific world, according to which there is a certain function of the coordinate and pulses of particles, which clearly characterizes the state of a closed macroscopic system, monotonously decreasing over time with irreversible processes and remaining constant in equilibrium state. The value of N is proportional to entropy, taken with the opposite sign. Entropy can either increase or remain constant. Boltsman formulated and proved this theorem in 1872, but some physicists and mathematicians against it, among them Joseph Loshmidt , is a teacher of Bolzman, and Ernst Keremelo , who began the assistant to Max Planck , based on the fact that the irreversibility of the mechanical movement of individual particles could not follow the irreversibility of thermal processes. Under the influence of criticism, Boltzman clarified his theorem, but many prominent physicists and mathematicians, including Brilluan, Poincare , and others, doubted the conclusions of the Vienna professor.

Paul Erenfest, while still a student, stood entirely on the side of Bolzman and later did a lot to confirm the rightness of his teacher. Both, the teacher and student, had similar characters: fondable, witty interlocutors, beautiful lecturers ... They were even similar from time to time attacked by bouts of depression. And they passed away both voluntarily in the prime of creative and physical forces.

In Erenfest’s office, a portrait of Bolzman was always hung, although Paul did not like to remember about their personal relations between them. And they, judging by the memoirs of the fellow student Erenfest Philip Frank , in the future of the first biographer Einstein, were not always smooth. Paul constantly strove for clarity and, with his persistent questions, could get out of himself the most patient lecturer. Once, an irritated professor asked: does Mr. student consider his lemon, from which you can completely squeeze all the juices? (Frenkel, 1977, p. 29).

When the Bolzman in 1901 accepted the invitation to become a professor in Leipzig, Paul went to Gettingen, where he spent more than a year and a half. He did not lose time there for nothing, judging by his registration book, he attended at the university until fifteen lecture courses (Frenkel, 1972). More than others, he was interested in the lectures and seminars of Felix Klein , which were distinguished by the exceptional breadth of the subject: from the theory of numbers to technical mechanics, from geometry to the theory of elasticity ... Klein had few listeners, so he soon drew attention to the reciprocating student. Felix Klein, like David Gilbert , can also be classified as Erenfest teachers.

Tatyana Afanasyeva also listened to Klein's lectures, where she met a living and witty student from Vienna. Tatyana Alekseevna loved and knew how to study. In St. Petersburg, where she lived with Aunt Sofya Evgenievna, Tatyana in 1893 graduated from the Mariinsky Gymnasium with a gold medal, after that in 1896 the pedagogical courses of the female St. Petersburg gymnasiums were held with the second gold medal and, finally, in 1900, the third gold medal completed training at the mathematical department Higher female (Bestuzhev) courses. In the fall of 1902, she “ with the highest permission is sent abroad for a period of one year for improving in mathematics and physics” (Frenkel, 1977, p. 28).

For improvement, Tatyana chose Gettingen, where she and aunt rented a small apartment. Sofya Evgenievna was a bakery mistress, and young people were constantly gathering in their apartment. Once Paul Erenfest went there and was fascinated by a direct atmosphere in the house. Very soon, Paul and Tatyana became inseparable.

Erenfest did not have to stay in Gettingen for too long, it was necessary to complete the university education. In 1903, Bolzman returned to Vienna, and Erenfest with his new friend also moved to the Austrian capital to defend a doctoral dissertation there, begun under the leadership of Bolzman.

True, Erenfest allowed himself to leave Vienna for a couple of months: together with the Getting friend Walter Ritz in April - May 1903, he traveled to Leiden, where the great Dutch physicist Lorentz lectured. It was at the lectures of Lorenz Erenfest that he joined the issues of theoretical physics with which he dealt with the next decades.

For the rest of his life, Paul Erenfest remembered the visit of Lorenz in his apartment in Leiden, held at the end of a trip to Holland. It turns out that in 1903 Lorenz also remembered this meeting for a long time. This acquaintance will play an important, one might say, fateful role in Paul's life. Erenfest considered Lorenza, along with Bolzman, Hilbert and Klein.

In June 1904, Paul Erenfest successfully defended his dissertation and became a doctor of philosophy of Vienna University. This honorable scientific title did not guarantee constant work, but it was the first step on the path of a scientific career. The next should be, as a rule, the defense of the second dissertation (habilitation) and obtaining a license for the right to give lectures at universities, the so -called Venia Legendi. It is unlikely that then someone could have assumed that the path from the defense of the doctoral dissertation to get a permanent place of work would take Erenfest for long eight years. Similar thoughts did not occur to the head, other problems took care of young people: Paul and Tatyana decided to get married, but difficulties immediately arose.

The fact is that between Christian Afanasyeva and Jew Erenfest under the Austrian laws, neither civilian nor church marriages could not be concluded. And only if both refuse to belong to religion, they could become a husband and wife. So they did, and on December 21, 1904, the Vienna municipality registered their marriage. The abandonment of belonging to any religion greatly complicated Erenfest’s life in those years when he unsuccessfully sought a place of work.

A month earlier, Tatyana Afanasyeva received official permission to attend lectures at the University of Vienna (unlike Prussia, in Austria-Hungary, this right was given to girls only in the order of exception) and since the spring of 1905 she had listened to several lectures on physics and mathematics in Vienna.

Then the young couple moved again to Gettingen, where they worked together on a number of scientific articles. Paul was interested in issues of the theory of relativity and quantum radiation theory, his articles on these topics were published in the leading scientific journals of that time and made Erenfest’s name known in scientific circles. In addition, Paul, along with Tatyana, prepared in October 1906 an article “On one task of probability theory associated with a kinetic interpretation of an increase in entropy”. The article contained criticism of the arguments of Loshmidt and Ceremelo who attacked the H -theorem. Unfortunately, the author of the theorem himself did not see this article aimed at defending it. Suddenly for everyone in September 1906, Professor Ludwig Bolzman committed suicide. He was only 62 years old. Despite all the difficulties of their personal relations, it was a huge loss for Erenfest. Bolzman gave a lot to a novice scientist, and Paul always remembered this. A month after the death of the teacher, life unexpectedly gave the young doctor a chance to give a debt to a great physics. At the same time, Paul got the opportunity to change his life for the better. But then no one thought about this, because before the treasured turn of fate remained for another five years. In the meantime, the first signal of future changes was the modest postcard from Felix Klein received by Erenfest in early October 1906: “ Dear Mr. Doctor! Would you be able to come tomorrow (on Friday), maybe with your wife to come at half the first in the meeting room or at 7 o’clock in the evening to my apartment, so that we could talk about your possible cooperation in the work of a mathematical society? F. Klein, devoted to you ”(Frenkel, 1977, p. 33).

In fact, this postcard was an invitation to make a report on the famous mathematical colloquium, regularly held in Gettingen, chaired by Felix Klein. Erenfest was not necessary to specially prepare for the performance-Pavel took a fresh joint article with Tatyana, aimed at the editorial office of Mathematisch-NaturWissenschaftliche Blätter . Therefore, the report on the mathematical colloquium took place in the same month, and a few days after the report, the Erenfates received a new postcard from Klein, containing a proposal, which could not be abandoned: “ Dear doctor, based on your report on colllox, which I all gave me a special pleasure, I want to contact you today with a big question or request. You would not have agreed, perhaps, together with the mistress of your wife, to prepare for the 4th volume of the encyclopedia a generalizing article on statistical mechanics; Initially, it was assumed that Bolzman would write it ... ”(Frenkel, 1977, p. 33).

The encyclopedia here means the famous “Encyclopedia of the Mathematical Sciences”, which since 1898 published the BG Teubner Verlag publishing house in Leipzig. This grandiose project was conceived by Felix Klein with colleagues and suggested in six voluminous volumes to present a modern level of not only mathematics, but also its applications in mechanics, physics, geodesy, etc. In writing articles for the encyclopedia, the leading scientists of that time took part: Mathematics David Gilbert, Karl Rongsheim, Ernst, Ernst Ceremelo, Max Denn, physicists Ludwig Bolzman, Hendrick Lorenz, Wolfgang Pauli, Hike Kamerling-Once, Arnold Zommerfeld, Theodore von Karman, Max Abrahag, Max Born, Max von Laue ... Encyclopedia was an international project, the authors of the articles became the scientists of different countries, if they occupied the leading position in the corresponding scientific field. For example, an article on the national economy was prepared by the Italian Wilfredo Pareto , the theory of the ship was written by the Russian shipbuilder Alexei Nikolayevich Krylov , on differential equations- Dmitry Fedorovich Selivanov , Honored Professor of Pure Mathematics of the Imperial St. Petersburg University, which the Bolsheviks who led the Bolsheviks from Russia at the famous "Philosophical Steamboat."

Klein’s proposal meant Paul and Tatyana Erenfest a great honor, but at the same time proposed such a responsible and difficult task, the solution of which took five years of hard work, mostly carried out in Russia, where the Erenfestes along with the little daughter of Tatyana (Tanya-Shatrich, as her name in the family) moved in the fall of 1907.

To be continued

Evgeny Berkovich

Einstein A. Memory of Paul Erenfest. Sobr. scientific. works. Volume IV, p. 190–192. M.: Science, 1967.

Rummer Yu. B. Physics, XX century. Novosibirsk: Arta, 2013.

Frenkel V. Ya. Paul Erenfest. M.: Atomizdat, 1977.

Frenkel V.Ya. Paul Erenfest. In the book: Erenfest P. Relativity, quanta, statistics. S. 308-337. M.: Science, 1972.