The creator of the first Russian scientific school of physicists was Peter Nikolaevich Lebedev. Pyotr Nikolaevich Lebedev - the most famous scientists of Russia

Petr Nikolaevich Lebedev

Lebedev Petr Nikolaevich (1866-1912), Russian physicist, founder of the first Russian scientific school of physicists. Professor at Moscow University (1900-11), resigned in protest against the harassment of students. First received (1895) and studied millimeter electromagnetic waves. Discovered and measured the pressure of light on solids (1900) and gases (1908), quantitatively confirming the electromagnetic theory of light. The Physics Institute of the Russian Academy of Sciences bears the name of Lebedev.

LEBEDEV Petr Nikolaevich (02/24/1866-03/1/1912), an outstanding Russian scientist, founder of the first scientific school of physicists in Russia. First received and studied millimeter electromagnetic waves (1895). Discovered and studied the pressure of light on solids (1899) and gases (1907), quantitatively confirming the electromagnetic theory of light. Ideas by P.N. Lebedev found their development in the works of his many students.

LEBEDEV Petr Nikolaevich (1866-1912) - Russian scientist, physicist, creator of the first physics school in Russia.

Professor at Moscow University in 1900-1911, where he created a physics laboratory. In 1901, he first discovered and measured the pressure of light on a solid body, quantitatively confirming Maxwell's theory. In 1909, he experimentally discovered and measured the pressure of light on gases for the first time. Investigated the role of the Earth's rotation in the emergence of terrestrial magnetism. The Physics Institute of the Russian Academy of Sciences is named after him.

Orlov A.S., Georgieva N.G., Georgiev V.A. Historical Dictionary. 2nd ed. M., 2012, p. 274.

Pyotr Nikolaevich Lebedev was born on March 8, 1866 in Moscow, into a merchant family. Petya learned to read and write at home. He was sent to the commercial department of the Peter and Paul Evangelical Church School. From September 1884 to March 1887, Lebedev attended the Moscow Higher Technical School, but the work of an engineer did not attract him. He went in 1887 to Strasbourg, to one of the best physics schools in Europe, the school of August Kundt.

In 1891, having successfully defended his dissertation, Lebedev became a Doctor of Philosophy.

In 1891, Lebedev returned to Moscow and, at the invitation of A.G. Stoletov began working at Moscow University as a laboratory assistant. The basic physical ideas of this plan were published by a young scientist in Moscow, in a short note “On the repulsive force of ray-emitting bodies.” The study of light pressure became the work of Pyotr Nikolaevich’s entire life. From Maxwell's theory it followed that light pressure on a body is equal to the energy density of the electromagnetic field. Lebedev creates his famous installation - a system of light and thin disks on a twisting suspension. The platinum wings of the suspension were taken with a thickness of only 0.1-0.01 mm, which led to rapid temperature equalization. The entire installation was placed in the highest vacuum attainable at the time. In the glass container where the installation was located, Lebedev placed a drop of mercury and slightly heated it. Mercury vapor displaced the air pumped out by the pump. And after this, the temperature in the cylinder dropped, and the pressure of the remaining mercury vapor decreased sharply.

A preliminary report on the pressure of light was made by Lebedev in 1899, then he spoke about his experiments in 1900 in Paris at the World Congress of Physicists. In 1901, his work “An Experimental Study of Light Pressure” was published in the German journal “Annals of Physics”. From the fact of the existence of pressure of electromagnetic waves, the conclusion followed that they have a mechanical impulse, and therefore mass. So, the electromagnetic field has momentum and mass, i.e. it is material, which means that matter exists not only in the form of matter, but also in the form of a field.

In 1900, while defending his master's thesis, Lebedev was awarded the degree of Doctor of Science, bypassing the master's degree. In 1901 he became a professor at Moscow University. In 1902, Lebedev delivered a report at the congress of the German Astronomical Society, in which he again returned to the question of the cosmic role of light pressure. On his way there were difficulties not only of an experimental, but also of a theoretical nature. The difficulties of the experimental plan were that the light pressure on gases is many times less than the pressure on solids. By 1900, all the preparatory work for solving the most difficult task had been completed. Only in 1909 did he make the first report on his results. They were published in the Annals of Physics in 1910.

In addition to work related to light pressure, Pyotr Nikolaevich did a lot to study the properties of electromagnetic waves. Lebedev's article "On the double refraction of rays of electric force" appeared simultaneously in Russian and German. At the beginning of this article, having improved Hertz's method, Lebedev obtained the shortest electromagnetic waves at that time with a length of 6 mm, in Hertz's experiments they were 0.5 m, and proved their birefringence in anisotropic media. It should be noted that the scientist’s instruments were so small that they could be carried in a pocket.

In the last years of his life, the problem of ultrasound attracted his attention. In 1911, Lebedev, along with other professors, left Moscow University in protest against the actions of the reactionary Minister of Education Casso. In the same year, Lebedev twice received invitations from the Nobel Institute in Stockholm, where he was offered the position of director of the laboratory and material resources. The question was raised about awarding him the Nobel Prize. However, Pyotr Nikolaevich remained in his homeland, with his students. The lack of necessary conditions for work and the worries associated with resigning completely undermined Lebedev’s health. He died on March 1, 1912, at the age of only forty-six years.

Pyotr Nikolaevich Lebedev was born in Moscow on February 24 (March 8), 1866. Even in his youth, he became interested in physics, so he chose the Imperial Moscow Technical School to study. Without finishing it, in 1887 Lebedev left for Germany, where he worked in the laboratory of the famous physicist August Kundt. In 1891 he wrote a dissertation and passed the exam for the first academic degree. Returning back to Russia, Lebedev received a position as an assistant in the physics laboratory of Professor A. G. Stoletov. The results of the work carried out in Kundt's laboratory formed the basis of his master's thesis, for which he was awarded the degree of Doctor of Physics. Soon Lebedev became a professor at the Imperial Moscow University. He did not limit himself only to research activities, but put a lot of effort into creating a scientific school, whose students in the future achieved success in the field of physics. In 1911, Lebedev left the Imperial Moscow University along with many progressive teachers in protest against the reactionary actions of the Minister of Education Casso. Using private funds, Lebedev created a new physical laboratory, but the research was not destined to be completed - the scientist died on March 1 (14), 1912 due to heart disease.

One of the prominent physicists of the 19th century, William Thomson, once wrote: “I fought with Maxwell all my life, not recognizing his light pressure, and now... Lebedev forced me to surrender to his experiments.”

According to the theory of the British physicist Maxwell, a light beam incident on an absorbing body produces pressure on it. Today, to a person far from physics, this statement may seem controversial, and even confirming the theory in practice may seem almost impossible. And in the 19th century, proving this statement even more represented a big technical problem, but talent and talent helped Lebedev successfully solve the problem. The difficulty of the experiment was that the amount of light pressure, if it existed, was very small. To discover it, it was necessary to conduct an experiment that was almost filigree in execution. For this purpose, Lebedev invented a system of light and thin disks on a twisting suspension. One can only wonder how the scientist managed to create torsion scales with such high accuracy of readings. However, in addition to the low pressure values, another difficulty was that other phenomena interfered with its measurement. For example, when light falls on the thin disks that Lebedev used in his experiments, they heat up. As a result of the temperature difference between the illuminated and shadow sides, convection effects occur. The scientist overcame all these difficulties, demonstrating unsurpassed skill.

At first glance, the device that the physicist designed seems very simple - the light fell on a light wing suspended on a thin thread in a glass container from which the air was pumped out. The twisting of the thread indicated light pressure. However, behind the external simplicity it is easy to overlook the hard work spent on its creation. The wing consisted of two pairs of platinum circles, one of which was shiny on both sides, the other covered with platinum niello.

The thickness of the platinum wings was as thin as possible, which led to instant temperature equalization and the absence of “side” effects. Additionally, to eliminate the movement of gas due to temperature differences, the light was directed alternately to both sides of the wing. In addition, the entire installation was placed in the highest possible vacuum for that time - Lebedev added a drop of mercury to a glass container with the device and heated it, as a result, the air was displaced under the influence of mercury vapor with the additional use of a pump. Then the temperature in the cylinder decreased, which led to condensation of mercury vapor and a sharp decrease in pressure. The scientist’s painstaking work was rewarded, and Lebedev reported that Maxwell’s theory was confirmed by his experiments. “Thus, the existence of Maxwellian-Bartholian pressure forces has been experimentally established for light rays,” Lebedev concluded his report on the discovery with this phrase. It is worth adding that the proven fact was of great importance for that time. And all because the reality of the existence of pressure of electromagnetic waves suggests that they have a mechanical impulse, and therefore mass. This in turn indicates that the electromagnetic field is material. Thus, scientists have proven that matter exists not only in the form of a substance, but even in the form of a field.

The next task that the physicist set himself was to determine the pressure of light on gases. This task was even more difficult than the previous one, since the light pressure on gases is many times less than the pressure on solids. It was necessary to conduct a more subtle experiment. It took a lot of time to prepare the experiment. Due to difficulties, Lebedev abandoned this idea many times, but then took it up again. As a result, about two dozen instruments were created, ten years were spent, but when the work was completed, the surprise of the scientific community knew no bounds, and the British Royal Institution elected Pyotr Nikolaevich as an honorary member. The difficulties that Lebedev encountered during the experiment were the same as during experiments with solids. In order for the gas temperature to be uniform, it was necessary to ensure strict parallelism of the rays, which is impossible to achieve in principle. However, the scientist’s ingenuity knew no bounds - he came up with the idea of ​​introducing hydrogen, which has high thermal conductivity, into the gas under study, which ultimately contributed to the rapid equalization of the temperature difference. All the results of Peter Lebedev's experiments and other studies coincided with the value of light pressure that Maxwell calculated, which was additional confirmation of his electromagnetic theory of light. For his unique experiments and general contribution to science, Lebedev was nominated for the Nobel Prize in 1912. Among the other candidates was Einstein. However, ironically, none of the great scientists received it that year: Einstein - due to the lack of experimental and practical confirmation of his theory of relativity (he received the prize only in 1921), and Lebedev - due to the fact that the prize was not awarded posthumously.

There was a professor at Moscow University, physicist Pyotr Nikolaevich Lebedev (1866-1912). Like Stoletov, Lebedev fought for a materialistic worldview. He was the mentor of many physicists. Among Lebedev's students were such prominent figures of Soviet science as academicians and P.P. Lazarev.

P. N. Lebedev saw science as a weapon in the struggle for the good of the people.

The scientist inevitably came into open conflict with the tsarist government.

In 1911, when the autocracy announced a new campaign against universities, Lebedev, along with a group of leading scientists, left the university in protest. The famous scientist was invited to work in Stockholm, at the Nobel Institute, but, despite the most flattering conditions that were offered to him, the scientist did not leave his homeland. Having created a small laboratory in the basement of one of the Moscow houses with private funds, the physicist and a group of young people continued their research.

But Lebedev’s health, undermined by all the adversities, deteriorated sharply, and in March 1912 the scientist died. He was only 46 years old.

Lebedev's discovery of light pressure brought him worldwide fame. He set this task for himself in his youth.

“I love this issue with which I have been busy for a long time with all my soul, just as I imagine parents love their children,” twenty-five-year-old Pyotr Nikolaevich Lebedev wrote to his mother in 1891.

The question that fascinated the young scientist was one of the most difficult in physics.

From the electromagnetic theory of light it followed that rays not only illuminate an object, but also put pressure on it. However, no one has yet been able to experimentally detect light pressure. How tempting it was to prove the existence of this pressure! After all, this would serve as another argument in favor of the truth of the electromagnetic theory of light, a theory that asserted that both light and the waves generated by an electric vibrator - radio waves, as we now call them - are closest relatives.

All these are electromagnetic waves, differing only in their lengths, the theory said.

And how important it was for astronomers to verify the existence of light pressure! Perhaps sunlight is the “wind” that deflects comet tails...

The failures of his predecessors did not frighten Lebedev. He set out to prove irrefutably, experimentally, the existence of light wind.

Lebedev did not immediately begin to solve his main problem. At first, he investigated the nature of waves, more powerful and larger - waves on water, sound waves, waves generated by electric vibrators. Through brilliant experiments, Lebedev established the effect of waves on the obstacles they encountered. Lebedev submitted his work “Experimental study of the ponderomotive action of waves on resonators”, in which he combined studies of waves of various physical natures, to Moscow University for a master’s degree. The academic council of the university highly appreciated this work: P. N. Lebedev was immediately awarded a doctorate.

While studying electromagnetic waves, the scientist managed to obtain very short radio waves. The mirrors Lebedev made to study and reflect these waves and the prisms made of sulfur and resin to refract them could be hidden in a vest pocket - they were so miniature. Before Lebedev, experimenters had to use prisms weighing several pounds.

Scheme of P. N. Lebedev’s experiment to determine light pressure on solids. The light of the electric arc located at point B, through a system of lenses and mirrors, falls on the wings of a miniature “mill” suspended in a vessel R from which air has been pumped out.

Diagram of the installation with which Lebedev discovered the pressure of light on gases.

Lebedev's research, remarkable for the subtlety of his experiments, had worldwide significance. But this was only the beginning of the work. The most difficult thing awaited the scientist ahead.

The forces of light pressure are unimaginably small. Suffice it to say that the bright rays of the sun hitting a palm placed in their path put pressure on it a thousand times less than a mosquito sitting right there.

The difficulties did not stop there. Under normal conditions, light pressure is drowned out by stronger extraneous influences. Light heats the air, creating upward currents in it. Light also heats the object itself - air molecules hitting a heated surface bounce off it at a higher speed than molecules hitting the unlit side. The action of upward flows and recoil of molecules far exceeds the pressure of light on an object.

To measure light pressure, Lebedev designed tiny pinwheels, which are thin metal wings suspended on a very thin thread. The light falling on the wings was supposed to turn them. To protect his device from extraneous influences, Lebedev placed it in a glass vessel, from which he carefully pumped out the air.

Having developed an ingenious experimental technique, Lebedev completely eliminated the influence of air flows and molecular recoil. Light pressure, not yet captured by anyone, in its pure form, visibly appeared before the wizard of the physical experiment.

Lebedev's report created a sensation at the World Congress of Physicists in 1900. William Thomson, who was present at the congress, approached K. A. Timiryazev after Lebedev’s report. “Your Lebedev made me surrender to his experiments,” said Kelvin, who spent his entire life fighting against the electromagnetic theory of light, which claimed, in particular, that there is light pressure.

Having proved that light presses on solids, Lebedev began to study an even more difficult problem. He decided to prove that light also puts pressure on gases.

Rays of light passing through the gas chamber designed by Lebedev caused it to move. They created, as it were, a draft that carried away gas molecules. The flow of gas was deflected by a thin piston embedded in the chamber. In 1910, Lebedev rightfully told the scientific world: “The existence of pressure on gases has been established experimentally.”

The significance of Lebedev’s work was not limited to the fact that they helped to establish the electromagnetic theory of light and gave the key to many astronomical phenomena. Lebedev proved through his experiments that light manifests itself as something material, weighty, and having mass.

From the data found by Lebedev it followed that the pressure of light and, therefore, the mass of light, the greater the brighter the light, the greater the energy it carries. An amazing connection has been established between energy and mass of light. The discovery of the Russian physicist went far beyond the theory of light.

Modern physics has extended the principle of the connection between mass and energy to all types of energy. This principle has now become a powerful tool in the struggle to master the energy of the atomic nucleus, the basis for calculations of atomic energy processes.

I considered him one of the first and best physicists of our time...

G. A. Lorenz

Only innate talent, the talent to understand, feel and guess the harmonious relationships in the eternal laws of nature, has encouraged and will encourage people to devote their time and work to the development of scientific questions...

P. N. Lebedev

He became a physicist contrary to family traditions and the will of his father. He was destined for a different path - commerce.

Lebedev's father served in the Moscow company of tea merchants Botkin. He conducted his business energetically and with constant success. The Lebedevs had two daughters and a son, Peter, born on March 8, 1866. His father looked at him as a future assistant who would eventually replace him in everything.

After three years of home schooling, the boy was placed in a private commercial school (Peter-Paul-Schule; the scientist called it the “Peter and Paul Church School”), where children of the middle-class German bourgeoisie studied. Here Petya Lebedev learned German perfectly and at the same time developed an aversion to commerce and accounting, although the latter taught him to be careful in business, which was later reflected in the keeping of laboratory reports and scientific diaries. Quite unexpectedly for those around him, the boy’s interest in technology arose. One of the reasons, apparently, was friendship with Alexander Eikhenwald, who was going to study as an engineer, and later became a prominent physicist.

But a very special role in the fate of Pyotr Nikolaevich was played by an acquaintance of their family - engineering officer Alexander Nikolaevich Beknev, a graduate of the Kronstadt Electrical Engineering School. One day he showed a 12-year-old boy several simple experiments on electricity, which completely captivated him. In 1896, responding to Beknev’s congratulations on conferring the title of privatdozent on him, Lebedev wrote: “To this day, I still remember and remember the colossal revolution in my entire worldview that you made with your electric machine from a plate of glass with cushions from officer gloves..."

Physics was also studied at the commercial school. Noticing Petya Lebedev’s interest in instruments and apparatus, the teacher began to use the inquisitive student as an assistant. At first, the father had nothing against his son’s hobby and even allowed him to purchase some electrical devices for home experiments.

Lebedev apparently did not study well at the commercial school (in one of his letters to his father, for example, he reports about his re-examination), but he enthusiastically reads popular science literature and the magazine “Electricity” that began to be published at that time. And his desire grew stronger and stronger - to take up electrical engineering. He even took a fancy to a higher educational institution - the Moscow Technical School (now Moscow Higher Technical School named after N. E. Bauman). However, the commercial school did not give the right to enter the institute. He tries to persuade his father to allow him to go to a real school, but the father, for his part, tries to dissuade his son. He specifically instills in him the habits of pleasure and an easy life: the boy had his own boat, riding horses, youth evenings and amateur performances were held in the house. Petya did not shy away from any of this; he was a cheerful, cheerful and sociable teenager. He loved theater, music, literature, and was fond of sports, but did not change his plans.

Seeing such persistence, his father finally agreed, and in 1880 (in the sixth grade) Petya transferred to the Khainovsky Real School. The most terrible memories of Pyotr Nikolaevich are associated with this educational institution: in its morals it was reminiscent of a bursa.

In addition to classes at the school, young Lebedev attends evening readings at the Polytechnic Museum and dreams of joining the Society of Lovers of Natural History, Anthropology and Ethnography.

By the beginning of 1882, his first attempts to engage in invention dated back. So, he improved the magnet tips in a telephone set, then developed an automatic traffic controller for a single-track railway. He sent his project to Beknev's court. He wrote in response: “The currents are directed absolutely correctly; the time of interruption and closure of the current was calculated well... I didn’t expect, to be honest, such a rapid movement from you in this area and such an attentive attitude to the subject.”

During these years, Lebedev began to keep a diary, recording in it not so much life events as reflections on the problems that worried him, his technical and physical ideas. On February 1, 1883, he wrote: “My constancy in relation to my invention surprises dad very much. Obviously, he would like me to rush from one thing to another, and then maybe I will change my desire to become an engineer.” The entry made by the young man on his 17th birthday is typical: “The purest, highest love, characteristic only of man, is the love of science, art and homeland.” The father kept hoping to convince his son; he thought that he would lose interest in electrical engineering. This, however, did not happen. And only six months later the “fighting parties” came to a final agreement. On June 15, an entry appeared in the diary: “Again I begin to write my diary with a purer heart than before, since now my technical career is decided.”

Pyotr Nikolaevich was distinguished by his persistence in achieving his goals; he always completed what he started with inspired perseverance. He believed that this trait was his father’s - “Lebedev’s”. Failures did not discourage him; one idea was immediately replaced by another; he ingeniously found a way out of the most difficult situations. In 1882 - 1883 he recorded more than forty of his inventive projects in his diary, sometimes accompanying them with brief explanations and even mathematical calculations.

Lebedev graduated from the Real College in 1883. He could not think about a university, since a university required a gymnasium education with Latin and Greek. Possessing a pronounced talent, he, however, did averagely well in both commercial and real schools, because he “wasted himself”, doing things that had nothing to do with the curriculum. And his general preparation, apparently, was low. He was unable to pass the exams at the Moscow Technical School, and a year later he did not pass them very well, so he had to resort to the patronage of the Moscow Governor-General. “A bad start to a technical career for a person who passionately dreamed of it,” notes Lebedev’s student and biographer Torichan Pavlovich Kravets.

In Russia at that time electricity was becoming more and more widespread, primarily for lighting purposes. In 1867, the dynamo was invented, six years later A. N. Lodygin invented the incandescent lamp; then the “Yablochkov candle” appeared. Electrical devices were already widely used. The number of people rushing to the thorny path of invention also grew. She was also chosen by Pyotr Lebedev. It is possible that as an inventor he would not have risen above the average level. But, fortunately, the young inventor suffered a setback that directed his aspirations in a different direction. He decided to build a so-called unipolar machine - an electric machine without an expensive collector, and for a long time, more than a year and a half, he tinkered with it and developed several options. “I invented, on the basis of the theories that existed at that time, such an ingenious machine, and I will say it now, that the director of the Gustav List plant suggested that I immediately build a machine with 40 horsepower; I made all the drawings, cast the car, made it (the piece cost 40 pounds) - and the current did not flow. My experimental activities began with this major fiasco; but this ill-fated experience, which almost pulverized me, did not give me peace until I found the physical cause that determined it - this radically turned my ideas about magnetism and gave them the form that I later learned abroad from the English authors.

It is very possible that my first debut in electrical ingenuity could have ended happily and with great effect, which, of course, would have forced me to take a different path, and then I could hardly have switched to the scientific path, but the misfortune with the machine resulted in a very stubborn and versatile work of thought on the cause of a phenomenon; “I little by little moved from technical applications to the phenomena themselves, and my thoughts began to swirl about how I could illustrate the foundations of my magnetic theory experimentally - without noticing it myself, I moved from technology to the scientific sphere.”

To cover the loss, the unlucky inventor had to work for several months as a technician at the Liszt plant without pay. (This plant was located on the Moscow River, opposite the Kremlin.)

How were his student affairs going? In a letter to Beknev, Pyotr Nikolaevich answers this question with his characteristic frankness: “As a student at the Technical College, I was bad, sloppy and strange; When I was still in a German school going to the Technical College... I imagined the activity of an engineer as the activity of an inventor whose thoughts are carried out by a mechanic, but being at Liszt’s factory showed me the practice of life, and this made me somewhat shrink and recoil. Having arrived at the Technical School with a head full of all sorts of questions, with technical knowledge superior to that of all my comrades, and with an innate interest in the matter, I was faced with the most absurd, monstrous system: already knowing what practice required, I had to perform, for example, according to drawing, such nonsense that can never exist for even three days in practice and even in the form of a thought will not occur to the average person - this is on the one hand. On the other hand, I did not find in any of my comrades an interest in the matter on the merits, simply engineering talent: all of these were just students who learn what is offered to them, with only one thought about the test score; I was ten years older than them. From a student’s point of view, my entire stay at the Technical School was some kind of confusion: everything was disgusting to me, I shied away from everything and probably would have ended very badly - I would probably have been fired for stupidity and laziness.”

In his “Biography” (“Vita”), later attached to his doctoral dissertation, Pyotr Nikolaevich notes that he “listened to lectures on mathematics, physics and mechanics from the following gentlemen professors and associate professors: ... Davydovsky, Mikhalevsky, Shaposhnikov, Shcheglyaev, Zhukovsky, Sluginov". In addition, he reads a lot: one can name “Cosmos” by Humboldt, “The Origin of Species” by Darwin, “History of Philosophy” by Lewis, the works of Lomonosov, Stoletov, Mendeleev, Sechenov, Umov.

By the fourth year, Lebedev, however, realized: he should not graduate from Technical School, the engineering field was not for him. But the three years spent at the Technical School were not wasted, of course; There he acquired plumbing and carpentry skills, learned to draw, operate machines, use tools, and acquired certain knowledge about special technical subjects. Analyzing his technical mistakes, he became increasingly interested in questions of theory and the essence of physical phenomena. This contributed to his overall philosophical and scientific development. An inquisitive, searching young man wanted to become an explorer of the secrets of nature, a scientist. This is where he saw his calling.

What was to be done? Professor V.S. Shcheglyaev, who headed the department of general physics, gave good advice. Under his leadership, Lebedev completed his first scientific work. Seeing and understanding the difficulties of the talented student, the professor advised him to leave the Technical School and go abroad, for example to Strasbourg. Shcheglyaev himself studied there - at the Physics Institute of the University of Strasbourg - with the famous experimental physicist August Kundt, an outstanding scientist and teacher, head of the physics school. Professor Shcheglyaev had the highest opinion of the science he taught.

Lebedev somehow immediately believed in Kundt and decided to go to Strasbourg, where physics was also taught without asking for knowledge of Latin and Greek.

In August 1887, his father died suddenly of a heart attack. Pyotr Nikolaevich arrived in Strasbourg only at the beginning of October. Kundt liked the “student from Russia.” He was hardworking, diligent, and had an impeccable command of the German language. Lebedev also liked Kundt.

August Kundt became famous for his research in the fields of acoustics, optics, heat, and crystal optics. A student and follower of the outstanding experimenter Gustavus Magnus, he significantly surpassed him, especially in terms of the organization of science. Magnus was the initiator and organizer of educational physics laboratories and created the first laboratory at his own home with his own funds. Kundt managed to use state funds to build a large and excellently equipped Physics Institute - an impressive four-story building. In the last years of his life, Kundt was a foreign member of the St. Petersburg Academy of Sciences. Among his many students one can name K. Roentgen, V. A. Mikhelson, V. A. Ulyanin.

Seven years later, in a speech on the death of his teacher, Pyotr Nikolaevich stated: “...he created not only the best Kundt Physics Institute in the world, but also founded in it that international Kundt school of physicists, whose students are now scattered throughout the globe<...>If Kundt as a scientist, appearing to us in all the splendor of his talent, occupies one of the first places among the physicists of his time, then Kundt as a teacher is a completely exceptional phenomenon as a lecturer and as a leader of future leaders.”

Pyotr Nikolaevich did not go abroad as a student, but as an essentially established scientist with highly developed critical thinking, mastering the art of experimentation, and having learned from his own experience the relationship between theory and practice. He was distinguished by independence both in thoughts and in actions, which Kundt highly valued. Discerning extraordinary talent in the young Russian, seeing how he avoided stereotyped and beaten paths, Kundt admired his student, the scientific courage and originality of his thinking, the abundance of ideas that literally swarmed in his head.

Lebedev found in Kundt all the conditions for the development of his abilities. He had to work extremely hard, since his physical knowledge was imperfect and full of gaps. It was necessary not only to fill them out, but also to enter the circle of the latest scientific problems as quickly as possible. In his letters of those days, the leitmotif is joy, the happiness of knowledge. He wrote to his mother: “Every day I fall in love with physics more and more. Soon, it seems to me, I will lose my human image; I have already ceased to understand how it is possible to exist without physics.” “The colloquium, which so recently seemed to me no more attractive than an apocalyptic beast, has now turned into a source of pleasure.” “For me, every page of what I read contains more pleasure than labor spent on assimilation; Thus, from morning to evening I am busy with what I wanted to do since I was 12 years old, and I have only one sorrow - the day is short.”

In those years, Boris Borisovich Golitsyn, a future academician, an outstanding physicist and meteorologist, also studied with Kundt. The young people became friends and tried to help each other. Their life was subject to the strictest routine; they had to save every hour, almost completely eliminating entertainment. They even used lunch time rationally: while one was having lunch, the other one reviewed aloud what he had read for the day, then they switched roles. During country walks, they also talked about their academic affairs. There was so much periodical literature that they could barely cope with it.

Pyotr Nikolaevich also saved time in the laboratory. So, he used an old mercury pump, into which mercury had to be added every now and then. Lebedev got tired of this, and he designed a device for automatically supplying mercury. Now he could turn on the machine and leave the laboratory. Kundt liked the idea, although he scolded Lebedev for wasting his time for other purposes.

Of course, Lebedev knew more than just victories and successes; there were also failures and disappointments, when happy inspiration was replaced by a lack of faith in one’s own strength and in the correctness of the chosen path. However, he suppressed them and immersed himself in his studies again. He not only studies theory, reads the original works of Ampere, Maxwell, Faraday, Helmholtz, conducts intense experimental work, but also tries his hand (as if wondering what to give preference to, what to devote himself to) in various areas of physics. He carefully, pedantically and hardworkingly keeps his diaries (thick notebooks, similar to accounting ledgers). All ideas that interest him and plans for research, including future ones, go there. These pages, covered in large and clear handwriting (with diagrams, tables, calculations), allow us to look into the creative laboratory of the future scientist.

It was during this period that Pyotr Nikolaevich finally determined the direction of his aspirations: he was essentially most interested in the mystery of the origin of magnetism and electricity. He decided to study electromagnetic phenomena.

This was then the main direction of rapidly developing physics. We have already talked about the complex and intense struggle of various trends in science of that time in the essay about Maxwell, and noted the role of Faraday in the development of science and the significance of Maxwell’s works. Maxwell's theory, in particular, stated that electromagnetic waves must exist. Heinrich Hertz proved through a series of brilliant and precise experiments that these waves really exist. His experiments, which became known in 1888, literally shook up the scientific world. It’s easy to understand how excited they were for the young Russian physicist! It is not surprising that he was eager to contribute to this area.

In such a spiritual mood, Pyotr Nikolaevich Lebedev approached writing his doctoral dissertation.

He was then no longer in Strasbourg, but in Berlin, where he followed Kundt, who in 1888 took the Helmholtz chair at the capital's university. Here Lebedev listened to lectures by Christoffel, Emil Kohn, Helmholtz, Kundt and reports at the Physical Society. And at the colloquiums he met and became close to such outstanding young scientists as Heinrich Rubens and Max Planck.

Since it was necessary to take Latin at the University of Berlin, Kundt advised Lebedev to return to Strasbourg and there defend his thesis “On the measurement of dielectric constant vapors and the Mossotti-Clausius theory of dielectrics.”

Friedrich Kohlrausch, who replaced Kundt, was also a major scientist, but without the breadth and erudition of Kundt. He disapproved of Lebedev’s topic, but he still defended it. Back in April 1890, he conducted a series of successful experiments to study the dependence of the dielectric properties of a liquid on temperature. He was not interested in working on a new topic, but things were moving forward well. He wrote to his mother: “As for the dissertation, my only fear is that it will be too long - in principle, I am against long articles, since no one reads them.” “I press it as hard as I can and throw out everything I can throw away.”

By mid-June 1891, the dissertation was completed and presented to opponents, and was soon successfully defended. On July 23, 1891, Pyotr Nikolaevich received the right to be called “Doctor of Natural Philosophy” and jokingly wrote to his mother: “I humbly ask now to always attribute “D–r” - I’m not just me, but a Doctor of Philosophy!”

Lebedev's dissertation was published in volume 44 of the Wiedemann Annals (1891), the leading physics journal of the time, and was the first published work of the young scientist. Her colleagues received her favorably. However, the author himself did not particularly like this work, since, in fact, he did not complete it.

It is interesting that, simultaneously with the study of the dielectric constant of vapor, Lebedev is studying the problem of light pressure on the smallest particles in outer space. He wrote: “I seem to have made a very important discovery in the theory of the movement of luminaries, especially comets... the found law applies to all celestial bodies. Reported to Wiener; At first he announced that I had gone crazy, and the next day, having realized what was the matter, he congratulated me very much. At first I was under great nervous tension, but now that the law has been proven, I am not at all worried, partly perhaps because - I will not hide this - I am puzzled, even stunned by its generality, which I did not at first foresee. The law I have derived is not a matter of momentary intuition: I have been carrying its rudiments for about two years. A question that I have been busy with for a long time, I love with all my soul, the way I imagine parents love their children.”

On July 30, at the last colloquium at the University of Strasbourg, Lebedev spoke about his ideas. He tells his mother: “Today is a very important day in my life: today I spoke for the last time in Colloquiume about a question that has been occupying me continuously for three years: “On the essence of molecular forces.” I spoke with aestheticism (and spoke well - I know that) - I held a kind of penitent confession; “there was everything here: cupids, fears and flowers! - and comet tails, and harmony in nature. For two solid hours I spoke and at the same time showed experiments that created a sensation and succeeded for me in a way that rarely succeeds. When I finished, comments started pouring in , bickering, sarcasticness - everything is as it should be...”

Professor Kohlrausch offered Lebedev a position as an assistant at his institute (a very tempting offer, it must be said), but he refused without hesitation.

At the same time, not without doubts and sad forebodings, the young doctor was preparing to return to his homeland. In one of his last letters home we read: “The happiest time of my life was being in Strasbourg, in such an ideal physical environment. What will be my future fate - I only see a foggy spot with a big question mark. I know one thing - I will work as long as my eyes can see and my head is fresh and I will try to bring all possible benefit.”

Pyotr Nikolaevich returned to Moscow in mid-August 1891 with an extensive plan of scientific work, designed for many years. The plan consisted of four sections - A, B, C, D. Each of them had several subparagraphs. It is interesting that at that time the problem of light pressure did not yet seem fundamental to Lebedev: we find it in third place in the second section: “B. Experimental research... 3. Light and electromagnetic waves.” (The first section contained “theoretical considerations” related to Maxwell’s theory.)

Pyotr Nikolaevich's Strasbourg friend B.B. Golitsyn, who had already worked at Moscow University as an assistant to Professor A.G. Stoletov in the physics department, warmly recommended his gifted friend to him.

Alexander Grigorievich Stoletov became famous for his research on electromagnetism, the establishment of the law of electromagnetism and the discovery of the photoelectric effect. In the early 70s, he organized the first laboratory in Russia - first for teaching, and then for research.

At Stoletov’s invitation, Lebedev begins working in his laboratory. However, Stoletov was unable to secure even the position of assistant (laboratory assistant) for Lebedev. And only in March 1892 Pyotr Nikolaevich was enrolled as a full-time assistant (and even then without salary at first) in the laboratory headed by Professor A.P. Sokolov.

The laboratory of Moscow University, of course, could not be compared with Kundt’s laboratory at that time: it occupied several modest rooms of a two-story building in the courtyard on Mokhovaya Street. Lebedev could not imagine experimental work without a workshop at the laboratory and began to create it. He drew up an estimate for the necessary tools and a lathe (the latter cost 300 rubles). The amount of the application horrified Stoletov. As he foresaw, the university board refused to pay the bill, noting that a lathe had no place in a physics laboratory. Then Pyotr Nikolaevich, having rewritten the invoice, instead of the words “lathe” he wrote “exact drebanka” (from the German Drehbank - lathe), after which the invoice was signed. For his own research, he was allowed to fence off a “free corner” in the corridor.

At that time, the only place where Moscow physicists could communicate with each other was the Physics Department of the Society of Lovers of Natural History, Anthropology and Ethnography. It met in the building of the Polytechnic Museum, the chairman of the department was N. E. Zhukovsky.

This time marks the beginning of Lebedev’s acquaintance (and friendship) with such remarkable scientists as K. A. Timiryazev, I. M. Sechenov, N. A. Umov, who had a serious influence on the worldview of the young physicist. Timiryazev later recalled about Lebedev that he was a tall man “with a deep, penetrating gaze of beautiful, clear eyes, in which at the same time there seemed to be a spark of living, infectious irony, so familiar to everyone who knew Lebedev...”

Timiryazev’s description of the young scientist is also interesting: “I have never met a person in whom a deep and creative mind was so harmoniously combined with amazing endurance in work, and physical strength and beauty merged with such sparkling wit and infectious gaiety.”

While still in Strasbourg, Lebedev became interested in spectral analysis. Then this interest intensified. In 1991, Pyotr Nikolaevich published an article “On the repulsive force of ray-emitting bodies,” and a year later, at a public meeting of the Division of Physical Sciences of the Society of Lovers of Natural History, Anthropology and Ethnography, he read a report “On the movement of stars based on spectroscopic studies.” These works were highly appreciated by astronomers, including Russians - F.A. Bredikhin and V.K. Tserasky.

In 1894, Lebedev published the first part of his large work “Experimental study of ponderomotive (mechanical - E.K.)“action of waves on resonators.” Likening a real molecule to an oscillatory circuit capable of receiving and emitting electromagnetic waves of very high frequencies, he made models of molecules that made it possible to study the patterns of their interaction with electromagnetic waves. The emitting molecule (vibrator), depending on the natural frequency of vibration of the model of the receiving circuit (resonator), will either attract or repel it. “If we,” wrote Lebedev, “take the point of view of the electromagnetic theory of light, if we make the assumption that Hertz waves are light waves of a long period, then we can consider our experiments as an attempt to study the laws in basic terms using extremely large schematic models of molecules those molecular forces that are caused by the mutual emission of molecules." The general conclusion from the work: “The main interest of studying the ponderomotive action of wave-like motion lies in the fundamental possibility of extending the found laws to the region of light and thermal emission of individual molecules of the body and pre-calculating the resulting intermolecular forces and their magnitude.” And one more thing: “Taking the point of view of electromagnetic theory, we could apply the results discussed to the study of the repulsive effect of the Sun on cometary tails...”.

This work already demonstrated Lebedev's amazing experimental skill. Suffice it to say that the resonator, the oscillation frequency of which could be adjusted, had a rather complex device, and weighed only 0.8 grams!

Here the scientist first received electromagnetic waves with a length of 3 mm. Let us recall that before this, waves of 60 cm were known, obtained by Hertz himself. Lebedev set a kind of “record” that remained unsurpassed for a quarter of a century.

According to the main idea of ​​the work, the contours of which were outlined by the scientist at the farewell colloquium in Strasbourg, molecules emitting electromagnetic waves interact with each other. Thus, Lebedev's work was one of the first attempts to study the nature of molecular interactions and the first systematic study of the mechanical properties of the wave field. Numerous first-class experimenters, Lebedev's contemporaries, failed in their attempts to study this phenomenon.

At the beginning of January 1894, the IX All-Russian Congress of Russian Naturalists and Doctors took place in Moscow. When the message about the untimely death of Heinrich Hertz arrived, Pyotr Nikolaevich, at the request of Stoletov, who headed the physics section, at one of the evening sessions gave an overview of the research of the deceased and a demonstration - for the first time in Russia - of his experiments. The lecture was given with great enthusiasm, the experiments were a great success.

In preparation for this lecture, Lebedev had the idea to continue Hertz’s experiments. And a year later his work “On the double refraction of rays of electric force” appeared, immediately recognized as a classic. Lebedev wrote in it: “With further reduction of the apparatus, I was able to obtain and observe electric waves, the length of which did not exceed fractions of one centimeter (λ = 0.5 cm) and which were closer to the longer waves of the thermal spectrum than to the electric waves that Hertz used it in the beginning... Thus, it became possible to extend Hertz’s basic experiments to crystalline media and supplement them with the study of double refraction in crystals.”

From April to July 1895, Pyotr Nikolaevich was treated abroad. He visited Germany, Austria, Italy and at the same time lectured there about his new work with great success. K. A. Timiryazev later noted: “...Hertz waves required large rooms to detect them, entire metal screens as mirrors for their reflection, monstrous, several pounds in weight, resin prisms for their refraction. Lebedev, with his inimitable art, turns all this into an elegant little set of some kind of physical spillikins and with this collection of instruments, which fits in his coat pocket, he travels all over Europe, causing the delight of his scientific colleagues.”

Stoletov highly appreciated Lebedev's abilities and energy, his dedication to work and inexhaustible enthusiasm. Lebedev was entirely on the side of Stoletov and other progressive professors in their ongoing struggle with the officials who decided the destinies of public education. Stoletov, like Lebedev, had a direct independent character, was distinguished by great adherence to principles and belonged to those democratic scientists who (like Sechenov, Timiryazev, Zhukovsky) fought for the democratization of science, sought to clear the way for all talented people, and made high demands on the level of knowledge of students . Stoletov, in addition, fought against various kinds of idealistic movements in science - Machism, the philosophy of W. Ostwald. By doing this, he constantly made enemies for himself, and it took a lot of mental strength to fight them.

More and more appreciating Lebedev’s bright talent and dedication to his work, Stoletov brought him closer to himself, hoping that over time he would become his successor. Stoletov closely followed the successes of the young scientist and supported him in every possible way. When Pyotr Nikolaevich completed his work “On the double refraction of rays of electric force,” Stoletov made a presentation about it at a meeting of the Physical Society in Kyiv in the spring of 1895. On December 16 of the same year, in a postcard sent to Lebedev, Stoletov inquired with concern: “Why did you disappear? Are we being overwhelmed again by influenza or “light pressure”?”

On March 11, 1896, Lebedev gave the so-called test lecture for the title of privatdozent “On the phenomenon of electrical resonance.” The lecture was approved by the Faculty Council, and soon Pyotr Nikolaevich, at the suggestion of Stoletov, was approved with the rank of private assistant professor, receiving the right to teach an independent course.

On May 27, 1896, Stoletov died unexpectedly. The still fledgling private assistant professor Lebedev was left without the protector and leader he so needed. And very soon he himself became a target for enemy arrows. K. A. Timiryazev later wrote: “If a future historian of Russian culture ever looks into the university archive, he will find out that there was a moment when I spoke about it (Lebedeva - E.K.) the only defender - the moment when he was ready to leave Moscow University and flee to Europe. I have repeated more than once with pride that I saved it for Russia...”

During the last meetings, Stoletov seemed to bequeath to Lebedev his cherished thoughts about the future of science in Russia, about the development of the university laboratory, about the direction of his, Lebedev’s, own research. And Pyotr Nikolaevich always tried to put this will into practice.

Thus ended the first - “Stoletovsky” - period of Lebedev’s activity at Moscow University.

Pyotr Nikolaevich loved the lively conversation of colloquiums, debates, laboratory research and did not like exams or lectures, although he was an outstanding lecturer. After Stoletov’s death, when the question arose about replacing his courses, N.A. Umov and the Faculty Council treated Lebedev’s candidacy (at that time he did not even have a master’s degree in Russia) with some distrust. He was entrusted with a course at the medical faculty and only a few years later - at the natural sciences department. Later, Pyotr Nikolaevich began to read the optional course “Problems of Modern Physics” for physicists.

In 1897, Lebedev completed a major work on the ponderomotive action of waves on resonators. The first part of it was discussed above. The second and third parts consisted of studies with hydrodynamic and acoustic waves. The work was published in three issues of Annalen der Physik, and two years later it was published as a separate brochure in Russian. This study by Lebedev became, as it were, an introduction, an approach to his proof of the existence of light pressure.

Pyotr Nikolaevich presented his book to the Faculty Council as a master's thesis. Opponents N.A. Umov and A.P. Sokolov, supported by K.A. Timiryazev, petitioned the Council to immediately award the applicant a doctorate degree. The Council made such decisions extremely rarely, but in this case the high scientific value of the work left no one in doubt. Lebedev was awarded a doctorate. At the beginning of 1900, he was approved as an extraordinary professor and headed the department of physics.

Lebedev had been busy for several years with experimental proof and measurement of light pressure. These studies were destined to become the main work of his life, his main scientific feat.

The problem of light pressure has played an important role in science. The idea that light should exert pressure on bodies lying in its path was expressed by Kepler at the beginning of the 17th century; He saw this as the reason for the formation of cometary tails. Fresnel tried to measure this pressure. Maxwell then put forward the hypothesis about light pressure when developing the theory of electromagnetic oscillations. Adolfo Bartoli came to the same conclusion, but in a different way. Developing the theoretical achievements of Maxwell and Bartoli, Boltzmann discovered a relationship of enormous importance, later called the Stefan-Boltzmann law: E = σT 4 (the radiation density of a black body is proportional to the fourth power of its absolute temperature). “This relationship,” notes T. P. Kravets, “opens the way to the entire thermodynamics of radiant energy. And we see that her first decisive step could not be taken without the idea of ​​light pressure and without Maxwell’s expression for this pressure - an expression to the proof of the correctness of which the scientific life of P. N. Lebedev was devoted.”

Colleagues who knew about Lebedev’s plans predicted failure for him, especially since many first-class experimenters (Crookes, Rigi, Paschen, etc.) had already suffered a fiasco in this. However, this did not stop Lebedev. He generally avoided easy tasks. “I have to work to the limit of my strength,” he said, “and let others decide what’s easy.”

Pyotr Nikolaevich divided his task into two parts: the pressure of light on solids and the pressure on gases. To solve even the first part of the problem (the simpler of the two), the scientist had to overcome enormous difficulties.

The first difficulty is the insignificant amount of light pressure: on a surface of 1 m2, sunlight presses with a force of about 0.5 mg, a midge presses with more force than a light beam! It was necessary to build a device that would measure this pressure. However, this was not the most difficult thing. Some of the instruments created by scientists were so fantastically sensitive that they could measure pressure even less than the pressure of light. The paradox of the situation was that the pressure of light could not be detected and measured using these amazing instruments. Why? But because when illuminated tiny and thin metal and mica wings (disks) with a diameter of 5 mm, which under the influence of light turned and twisted the thread of the torsion balance, so-called radiometric forces arose, which were thousands of times greater than the force of the light pressure itself. She was simply lost in them!

These forces, extremely interesting for the kinetic theory of gases, were discovered by the famous “master of vacuum technology” William Crookes.

The mechanism for the emergence of radiometric forces is due to the fact that the illuminated side of the disk turned out to be warmer than the shadowed side. As a result, the gas molecules were repelled by it more strongly. And when a gas molecule is repelled from the disk, the phenomenon of recoil occurs, which will be greater on the warm, i.e. illuminated, side. As a result, a resultant recoil occurs, coinciding in direction with the desired light pressure.

In addition, the flow of gas flowing around the wings from their cold side to the hotter one also has a counteracting influence. These are so-called convection currents that arise due to uneven heating of the gas. Their counteraction is summed up with the resultant recoil.

It was known that radiometric forces and convection currents decrease as the gas becomes rarefied. Therefore, to get rid of them, it is necessary to place the wings in a vacuum. Crookes believed that with a vacuum of 0.01 mm Hg. Art. convection is no longer scary. However, in reality, a much larger vacuum was needed. During Lebedev's time, obtaining a pressure of the order of 0.001 mm Hg. Art. still presented considerable difficulties. And at this pressure, 1 cm 3 of a vessel contains more than 10 12 molecules - a huge amount! They did not allow the device to measure correctly.

The radiometric effect, which seemed to experimental physicists to be an insurmountable difficulty, was eliminated by Lebedev in a very simple and ingenious way. He pumped out to the maximum possible limit (at that time it lasted for days); A drop of mercury was placed at the bottom of the vessel in which a vacuum was created. When slightly heated, the mercury evaporated, its vapors displaced air from the vessel, which was carried away by the vacuum pump. Then the vessel was cooled to –39 ° C, mercury vapor, freezing, settled on the walls. The result was an almost ideal - for that time - vacuum: 0.0001 mm Hg. Art. (Subsequently, this idea of ​​diffusion capture and freezing formed the basis of the principle of creating the most advanced modern pumps.)

“Another method of reducing radiometric forces,” noted T. P. Kravets, “is associated with a deep analysis of their nature: they are explained by the difference in the “recoil” of gas molecules on the two sides of the irradiated disk - the front and back; the difference depends on the temperature difference on these two surfaces of the disk. Therefore, it is necessary to reduce this difference. Therefore, Lebedev refuses to use mica, glass and similar substances as materials for disks. In return, he takes metal, which is more heat-conducting and, moreover, in a very thin sheet form. He is very limited in his choice of metal: at low pressures, mercury vapor corrodes the surfaces of all metals, which form an amalgam with mercury. Lebedev's discs are made of platinum sheet, nickel and aluminum. This trick is considered by many to be the most important guarantee of Lebedev’s further success. Thus, his laboratory comrade Kundt Paschen writes to him, having received his first article from him: “Your skillful technique of throwing light on metal disks is the key to resolving the issue."

To get rid of convection currents, Lebedev also used specially designed wings.

Convection of gas flowing around the winglets depends on a number of factors.

1. From heating the walls of the vessel. To eliminate this reason, the scientist passed the light beam passing to the vessel through a whole system of glass plates-mirrors and lenses, and the rays absorbed by the glass were filtered.

2. From heating the gas remaining in the vessel. To eliminate this heating, Lebedev carefully removed water vapor and carbon dioxide and completely abandoned all kinds of putties, adhesives, lubricants, and rubber, since such substances are capable of releasing unwanted gases into the vacuum.

3. Gas convection is also influenced by the fact that the lightest (openwork) wings suspended on a thin thread can heat up, and from them the gas in the vessel surrounding them can heat up. This can be avoided in one way - to observe when illuminating the wings alternately from the front side, then from the back, and both sides must have absolutely identical optical properties. In both cases, the action of convection occurs in the same direction, while the total deflection of the wings is free from the influence of convection interference.

Augustin Fresnel, for example, failed precisely because his installation on the wing where the light flux fell was subject to convection interference, the mechanism of which the scientist did not foresee.

Lebedev had one half (let's say, the left) of his wings blackened, the other remained mirrored. The theory stated that the blackened areas completely absorb the incident light, which produces half the pressure on them than on mirror surfaces that completely reflect it. Observations confirmed this.

The force of light pressure measured by Lebedev turned out to be on average equal to 0.0000258 dynes. This figure, like others, differed from the theoretical ones by about 20%, always exceeding them. This means that Lebedev was not able to completely get rid of radiometric forces, but the scientist achieved that they became less than the forces of light pressure. And this in itself was a huge achievement.

Overcoming enormous and numerous difficulties, Lebedev demonstrated amazing, hitherto unprecedented mastery of the experiment. An essentially simple idea required truly heroic efforts from the scientist to implement it. And enormous physical exertion, unparalleled perseverance and patience, for the experiments lasted not a week, not a month, but about eight years! At the same time, understanding the mystery of physical processes more deeply than others, Lebedev had the gift of achieving success without resorting to any special tricks. His ideas are always very simple, but it is a simplicity that is rooted in genius. A. A. Eikhenwald, himself an outstanding experimenter, emphasized: “This work can be considered the pinnacle of the experimental art of modern physics.” The same idea was emphasized by Wilhelm Wien, who wrote to the famous Russian physicist V. A. Mikhelson that “Lebedev mastered the art of experimentation to an extent that hardly anyone else does in our time...”.

Pyotr Nikolaevich first reported the positive results of his experiments on May 3, 1899 at a meeting of the Society of Natural Scientists in Lausanne. (In Switzerland, the scientist was undergoing treatment, since the painfully stressful and difficult experiments ended for him with several serious heart attacks. But he was so passionate about the work that when doctors called for him to give himself a break, he answered: “Even if I die, but I will complete the work!” )

However, Pyotr Nikolaevich himself was dissatisfied with his Paris report and immediately began to redo it. He worked, as always, with great enthusiasm and tension, often for days and nights, and by the summer of 1901 he had brought himself to extreme exhaustion. He told one of his close friends then: “The general state of health is poor: they tried all the drugs on me without results, now they have begun to electrify me; The more I hurt myself, the better I heal. My task now is modest, but also, it seems, unattainable: to become so electrified that I can work with electricity without much pain.”

In 1901, Lebedev’s article “Experimental studies of light pressure” was published in the “Journal of the Russian Physico-Chemical Society” and in “Annalen der Physik”, in which he summed up the results of the work he had done; This article immediately became a classic. It ended with the words: “Thus, the existence of Maxwell-Bartoli pressure forces has been experimentally established for light rays.”

Yes, confirmation of the theoretical assumptions of Maxwell and Bartoli about the presence of light pressure and its quantitative measurement is the great scientific and historical merit of Pyotr Nikolaevich Lebedev.

However, the matter was not limited to this: Lebedev’s work seemed to throw a bridge into the future of science - to its future achievements, on the threshold of which physics then stood. T. P. Kravets writes: “Further steps in the thermodynamics of radiation are impossible if we do not recognize that light pressure exists. Thus, Wien's displacement law is based on the formula for pressure on a moving mirror. And finally, the famous Planck formula, which for the first time in physics reflected the idea of ​​atoms of radiant energy - quanta, or photons; This formula also historically could not be obtained without an idea of ​​light pressure.

But ideas of an even different order are associated with light pressure. If radiant energy falls on a body, exerting pressure on it, then, consequently, it transfers a certain amount of motion to this body. And from recognizing the connection between energy and momentum, it is only one step to the connection between energy and mass. This concept was brilliantly derived by Einstein from the principle of relativity."

Friedrich Paschen wrote to Lebedev from Hanover: “I consider your result one of the most important achievements in physics in recent years and I don’t know what to admire more - your experimental art and skill or the conclusions of Maxwell and Bartoli. I appreciate the difficulties of your experiments, especially since some time ago I myself set out to prove light pressure and carried out similar experiments, which, however, did not give a positive result, because I was unable to exclude radiometric effects.”

Lebedev becomes a world famous scientist. His articles are translated into many languages, friends and students send him enthusiastic letters, and the seriously ill scientist does not lose heart, believes in the possibility of recovery and that he will return to his favorite work.

During treatment, he wrote one of his best popular articles, “The scale of electromagnetic waves in the ether,” and on August 4, 1902, he spoke at the congress of the German Astronomical Society with a report “Physical reasons for deviations from Newton’s gravitational law,” in which, in fact, affairs, returns to the ideas raised by him in the work of 1991 - “On the repulsive force of ray-emitting bodies.” At the same time, this report closes the cycle of the scientist’s work on light pressure on solids.

In 1904, the Physics Institute moved to a new building in the university courtyard. Lebedev's laboratory and workshop were located in two rooms on the second floor, and his students and their household were given a basement; Pyotr Nikolaevich chose it so that the instruments would be subject to less shaking. Soon this place became famous as the “Lebedev cellar”. Pyotr Nikolaevich himself moved from his parents’ wing on Maroseyka, where he had lived for so many happy years, to a small apartment above his laboratory. It was more convenient for the sick scientist: he could now go down to his laboratory and to his students at any time of the day, if necessary. Contrary to the doctors’ prohibitions, conversations with them often dragged on for long hours, until late at night. Pyotr Nikolaevich’s nerves weren’t doing well either; he became irritated more often; the failures in the work of his students now depressed him more and more. “Stormy, unbalanced,” characterizes him V.D. Zernov, one of his students, “sometimes harsh, sometimes affectionate, completely absorbed in the interests of his work and the work of his students, always burning and so soon burned out.”

Soon a serious event occurred in the life of Pyotr Nikolaevich: he married the sister of his friend Eikhenwald, Valentina Alexandrovna. She became a true friend of the scientist and did everything possible to make his life and work easier.

In the summer of 1902, despite worsening heart disease, Pyotr Nikolaevich took on an even more difficult task - measuring the pressure of light on gases. He had been nurturing the idea of ​​the experiment for ten years. Although Sommerfeld, Arrhenius, Schwarzschild and other luminaries of science denied the very possibility of this kind of pressure, Lebedev was convinced of the opposite, like many astronomers and physicists of that time. It was they who expected Lebedev to take on the solution to this problem: there was no other scientist capable of coping with an experiment of such difficulty.

The pressure of light on gases, Lebedev argued, certainly exists, but it is hundreds of times less than the pressure of light on solids. Lebedev presented his proof of the existence of light pressure forces on gas molecules in August 1902 in Göttingen at the congress of the German Astronomical Society.

Some scientists considered the idea of ​​the experiment trivial (why, they say, was it necessary to measure light pressure especially in gases?), although, according to everyone’s unconditional opinion, its implementation certainly represented a masterpiece of experimental art. The experiments required almost ten years of intense and persistent work from Pyotr Nikolaevich.

The idea of ​​the experiment was as simple as in the case of measuring light pressure on solids. But this simplicity had its own enormous difficulties. In the first case, the scientist’s art was reduced to creating a maximum vacuum, neutralizing the remnants of gas molecules from the impact on the measuring device; here, at normal pressure, which sharply increased the interfering effects, the gas molecules had to move in concert in the direction of the light flow, push the lightest piston connected to the rocker arm of the torsion balance. Porshenek, notes Lebedev, “was machined from magnalium: with 4 mm in length and 2.85 mm in diameter, it weighed less than 0.03 g.” More than twenty instrument options were tested until the one most suitable for the experimental conditions was found. Lebedev once again demonstrated to the world that he is one of those legendary Leskov craftsmen who are able to shoe even a flea.

The installation on which P. N. Lebedev proved the existence of light pressure on gases.

The situation with the choice of gases for research was not simple either. The most suitable were hydrogen mixtures of gases such as carbon dioxide, methane, ethylene, propane and butane. “The study of other gases,” Lebedev wrote, “had to be discarded, since they either had a very low absorption capacity or could have a chemical effect on the piston device.”

The initial experiments stretched over five years, requiring enormous technical ingenuity and nervous tension. K. A. Timiryazev says about the events of that time: “... this task seemed completely insoluble... But overcoming the insurmountable has already become Lebedev’s specialty. The story of his new work is not without some dramatic interest.

Several years ago, sick, exhausted by our damned exams, he took a vacation prescribed by his doctors somewhere in the mountains - in Switzerland. On his way, he stops in Heidelberg and climbs the Königstuhl tower, to the Wolf Astronomical Observatory. The famous scientist tells him that the eyes of all astronomers are turned to him, that only from him do they expect a solution to the problem that interests them.

Thoughtfully descending back from Königstuhl, Lebedev again thinks about the problem that has occupied him for a long time and finally finds its solution. The next day, forgetting about the necessary rest and the doctors’ orders, instead of continuing his journey to the south, he turns north, to stuffy, dusty Moscow. Days and nights, months and years, work is in full swing, and in December 1909 Lebedev speaks before the Moscow Congress of Naturalists with his work “On the Pressure of Light on Gases,” in which he surpassed himself in his experimental art.”

The successful result of Lebedev’s research was first reported on December 27, 1907 at the First Mendeleev Congress (at a meeting of the physics department), but they were completed only two years later - by December 1909. The scientist demonstrated the results of his truly ascetic work at the Moscow Congress of Natural Scientists and doctors. The final article “Experimental study of the pressure of light on gases”, presented on 25 pages, is dated February 1910. In the same year it was published in the “Journal of the Russian Physicochemical Society”, and then in “Annalen der Physik” and in the English “Astronomical magazine." The article ended with the words: “Thus, the hypothesis about the pressure of light on gases, expressed by Kepler three hundred years ago, has now received both theoretical and experimental justification.”

The scientific world was again shocked by Lebedev's results. Many colleagues sent their congratulations to Pyotr Nikolaevich. One of the first to respond was the famous astronomer and physicist Karl Schwarzschild: “I well remember with what doubt I heard in 1902 about your proposal to measure the pressure of light on a gas, and I was filled with even greater surprise when I read how you removed all the obstacles.” .

Many years later, A.K. Timiryazev, the son of Klimenty Arkadyevich, a famous physicist, wrote that this work of Lebedev remained unsurpassed: “The pressure of light on solids was measured by many scientists, repeating Lebedev’s experiments. Light pressure on gases has not yet been repeated by anyone. No one has yet dared to follow Lebedev’s path!”

A representative of the younger generation of Pyotr Nikolaevich’s students, S.I. Vavilov, later wrote: “P. N. Lebedev foresaw the enormous role of light pressure in the life of the Universe. Modern astrophysics has fully confirmed this expectation; Every year the primary role of light pressure in cosmic processes is increasingly revealed, and its value becomes equivalent to Newtonian gravity. On the other hand, the proven fact of light pressure has enormously facilitated the concretization of the inextricable connection between mass and energy, which was elucidated throughout the entire breadth by the theory of relativity. The elementary light pressure of modern quantum physics, the photon moment hv/c, is a generalization of Lebedev’s experiment. On the basis of this generalization, it became possible to understand the features of scattering of X-rays and gamma rays. The so-called Compton effect is essentially the implementation of Lebedev's experiment in an elementary process during the collision of a photon and an electron. Thus, Lebedev’s work on light pressure is not a separate episode, but the most important experimental unit that determined the development of the theory of relativity, the theory of quantum and modern astrophysics.”

On May 4, 1905, the Russian Academy of Sciences “in view of the outstanding scientific merits ... of experimental research on the issue of light pressure” awarded Lebedev a prize and elected him a corresponding member. On July 21, 1906, he received the title of full professor.

In 1911, the Royal Institution of Great Britain elected him as an honorary member. Before Lebedev, only one Russian scientist was awarded this honor - D.I. Mendeleev.

But Lebedev himself saw in all this not so much his personal success as the success of the school of Russian physicists he headed.

In 1910, Lebedev's main scientific program was basically completed, and completed brilliantly.

By this time, the scientist was deeply interested in a number of other scientific problems. Thus, while studying the light pressure on gases, he began to work on the question of the Earth’s motion in the ether, creating several original instruments that amazed with their ingenuity, design talent and incomparable art of overcoming experimental difficulties.

“A distinctive feature of Pyotr Nikolaevich’s research,” wrote N.A. Umov, “was that it was carried out in areas of nature inaccessible to the ordinary experimenter; Only his ingenuity and remarkable technical skill gave him courage and crowned with success the tasks he set for himself.”

Meanwhile, Lebedev begins to become increasingly interested in astrophysics. He participates in the work of the International Commission for the Study of the Sun, joins the discussion about the change in the speed of light in the interstellar medium depending on the wavelength, and even publishes several small articles about this, where he was the first to correctly point out that the cause of the phenomenon cannot be contained in the medium itself.

In April 1909, the scientist noted in his diary: “I am studying terrestrial magnetism in connection with the discovery of the Gel of sunspot magnetism.” This was the most significant study of the last years of Pyotr Nikolaevich’s life, although it was not crowned with success.

In Lebedev’s laboratory there was a special mechanic for the manufacture of instruments - Alexey Akulov, a man devoted to Pyotr Nikolaevich, who had worked with him for more than twenty years, a real mechanical artist. He wrote: “At first I received the most detailed sketches from P.N. But at the same time, he tried to instill independence in me. He gave a lot of effort so that I could comprehend this wisdom. He himself was a good craftsman and often at night he would finish the work I had not finished. P.N. required his students to know the basics of plumbing. He said more than once that only in this case will the physicist know what can be demanded of the mechanic.”

A significant part of the instruments in the “Lebedev basement” was manufactured by the workers themselves. V.D. Zernov says: “...everyone makes his own instruments of labor, for these are not ready-made devices, but devices that are improved as the experiment develops - as the research problem itself develops. “Everyone is a mechanic, a carpenter, an optician, a glass blower, sometimes a virtuoso who cannot be found in any workshop of the most famous company.”

V.K. Arkadyev gives a description of this laboratory: “Whoever was accustomed to the brilliance of ordinary equipment in physics classrooms in gymnasiums or demonstration apparatus in university auditoriums could not help but be surprised by the rough appearance of unplaned boards, unsawed castings and other unfinished parts of those structures with which he mostly worked Lebedev. These instruments were hastily manufactured right there in his laboratory and were immediately used to reproduce new phenomena that had never before been seen by anyone. Depending on the requirements of the experimenter, sometimes under the influence of a newly arising thought, these devices were often redesigned on the spot, receiving a new, more rational form. They were placed on separate tables in a large empty hall, the very spaciousness of which was in harmony with the free flight of the scientific imagination of its inhabitant. In experiments with devices of this “wild” type, critical parts of which were often ordered from world-famous companies, new physics was born. Those who visited the laboratory could see here a scientific idea at the moment of its emergence.”

Lebedev was one of the first scientists in the history of science who realized that a collective form of research work - according to a single scientific plan, with the solution of complex problems - is the most appropriate and promising. Immediately upon returning from Strasbourg, Pyotr Nikolaevich begins to work in this direction - on the creation of a school of Russian physicists and a “Russian national laboratory”, because “the need for it and the necessary scientific forces are obvious.”

A.G. Stoletov, for example, had many students, but he did not create his own school - circumstances turned out to be stronger than his intentions. In the article “In Memory of the First Russian Scientist,” Lebedev wrote with heartache “about the educational corvée that Mendeleev, Sechenov, Stoletov and currently living major Russian scientists served, just to gain the right to conduct their scientific work, in order to pay for the opportunity to glorify Russia with their discoveries.” .

It was difficult to work; more than once Pyotr Nikolaevich bitterly complained about the scientist’s powerless position. Neither officials from the Ministry of Education, nor university authorities, nor colleagues shared the views of the young scientist; they believed that it was not the job of universities to create scientific schools or worry about replenishing the ranks of scientists. “Why,” they asked Lebedev, “do you recruit students and spend so much time and so much effort on supervising their work? We don’t need this, the university is not the Academy of Sciences.” What became a self-evident truth abroad was received with hostility in Russia. Of course, over the years, when scientific fame came, his position at the university became stronger, his work became easier, and fewer obstacles were created. At first, the position of the young scientist, who sought to make scientific work one of the main tasks of university education, was incredibly difficult. Pyotr Nikolaevich patiently and carefully nurtured each of his students, persistently instilled in them his ideas, and instilled working skills. The number of his students increased. “Keep in mind,” he told them, “the time will come when physicists in Russia will be needed and will find use for their strengths.”

P. N. Lebedev, notes Kravets, was “an integral and deeply interesting person. He amazed everyone with his extraordinary appearance: enormous height, equally enormous physical strength, trained in sports in his youth (rowing, mountaineering), with a beautiful face - he showed the image of courageous beauty in the highest sense of the word. He came to the circle of his fellow Moscow scientists from a different environment and differed sharply from the average intellectual in education, manners, and clothing, so among them he was not always considered “one of their own.” His conversation was original, imaginative and never forgotten. Like his teacher Kundt, he did not seek popularity, did not curry favor with the audience, and was sometimes extremely harsh with his students. His demand for work, both his own and that of others, reached the extreme. And yet the charm of his talent was such that working for him was considered a rare happiness.”

“Peter Nikolaevich,” wrote N. A. Kaptsov, one of Lebedev’s students, “was a very deep and very subtle experimenter. This does not mean at all that he did not attach any importance to the theory. So, for example, in the question of wave pressure, he demanded familiarity with the works of Rayleigh, who developed the question of pressure for any types of oscillations, and demanded that those of his students who dealt with the issues of pressure of certain waves master this, then quite difficult theoretical for us side of the issue. If Pyotr Nikolaevich himself did not engage in mathematical calculations, then he thought through all phenomena from a theoretical point of view, relying on his amazing intuition, which allowed him to predict a lot without formulas.”

At the First Mendeleev Congress in 1907, Pyotr Nikolaevich could not attend for health reasons; Kravets, Lazarev and Zernov were sent - representatives of Lebedev's school, a single and cohesive scientific team that had not existed in Russia before. The packed auditorium at St. Petersburg University greeted their achievements and their leader, Pyotr Nikolaevich Lebedev, with thunderous applause.

“The talent of a leader,” wrote T. P. Kravets, “is a special talent, often completely different from the talent of a research scientist: the brilliant Helmholtz almost did not create a school; not a genius, but only a very talented teacher P. N. Lebedev August Kundt created a brilliant galaxy of students.

The enormous talent of a researcher in P. N. Lebedev was combined with an extraordinary talent of a leader. And without in any way detracting from the significance of his scientific works, one can ask: wasn’t his main, best talent, the talent of a leader?”

In the last years of his life, Pyotr Nikolaevich almost never left the Physics Institute, where his apartment was located, going down only to the laboratory. Walking down the street, especially in cold weather, caused him to have attacks of angina pectoris. He always had a painkiller drug with him and, in case of an attack, took it, often stopping mid-sentence.

Soon the scientist’s weakened health was dealt a severe blow.

Those were the years of rampant Stolypin reaction. At the university, as throughout the country, everything progressive and advanced was brutally suppressed. In January 1911, when student unrest began, the Minister of Education Casso issued an order in which the administration of higher educational institutions was actually charged with the functions of informants. The Council of Moscow University, at the initiative of the rector, decided not to comply with this order. In response, the minister dismissed the rector and his two assistant professors. In protest, a large group of professors left the university, including K. A. Timiryazev, N. D. Zelinsky, N. A. Umov, A. A. Eikhenvald.

Lebedev, like none of the professors, was in the most disadvantageous position: he had no part-time jobs, no special savings, and also, due to his age, no right to a pension. When he left the university, he lost his department, his government apartment, and most importantly, his laboratory, that is, absolutely everything. “Historians, lawyers and even doctors,” said Pyotr Nikolaevich, “they can leave right away, but I have a laboratory and, most importantly, more than twenty students who will all follow me. It is not difficult to interrupt their work, but to arrange them is very difficult, almost impossible. This is a matter of life for me.” And yet he also left the university.

When news reached Svante Arrhenius that the famous professor Lebedev was out of work, he immediately invited him to Stockholm, to the Nobel Institute, of which he was then director, promising excellent working conditions, including a laboratory and high pay (“how is this corresponds to your rank in science,” wrote Arrhenius). Pyotr Nikolaevich twice rejected this tempting offer, although at that time the question of awarding him the Nobel Prize was raised. He also refused a place in the Main Chamber of Weights and Measures, because he firmly decided not to leave either Moscow or his students and believed that some way out would be found.

And a solution was indeed found: the public of Moscow came to the scientist’s aid. Already in the spring of the same 1911, using the exquisite funds of the Kh. S. Ledentsov Society and the City University named after A. L. Shanyavsky, premises were rented in Dead Lane, house number 20 (now N. Ostrovsky Street) and the most necessary equipment was purchased. Over the summer, under the leadership of mechanic Akulov, two basement rooms and a workshop were equipped. In the same house there was also an apartment for Pyotr Nikolaevich, who was then receiving treatment in Heidelberg. In September, the Lebedev basement was already working normally. So Pyotr Nikolaevich managed to preserve the school of physicists he nurtured.

In the same year, also with funds from the Ledentsov Society and Shanyavsky University, construction began (especially for Lebedev’s school) of the Physical Institute, which later turned into the Physical Institute of the Academy of Sciences, which was named after P. N. Lebedev. Pyotr Nikolaevich was directly involved in its design, as evidenced by the surviving sketches and plans drawn by his hand.

Pyotr Nikolaevich was full of broad plans and the brightest hopes. It seemed to him that his business was finally gaining the proper scope. However, the scientist’s health was irreversibly undermined. In January 1912, attacks of heart disease worsened. In February, Pyotr Nikolaevich fell ill, and on March 14 he passed away. He died at the age of 46, in the prime of his extraordinary talent.

“It’s not only the guillotine knife that kills,” K. A. Timiryazev wrote with anger. “Lebedev was killed by the Moscow University pogrom.”

I. P. Pavlov’s telegram said: “With all my soul I share the grief of the loss of the irreplaceable Pyotr Nikolaevich Lebedev. When will Russia learn to take care of its outstanding sons - the true support of the fatherland?! The exiled students responded with the following telegram: “We mourn with all thinking Russia the death of the staunch defender of the Russian free school, free science, Professor Lebedev.”

The Moscow Physical Society and the scientist's widow received about a hundred letters and telegrams, of which 46 were from Western scientists. “The name of Lebedev,” wrote Arrhenius, “will invariably shine in the field of physics and astronomy, to the glory of his time and homeland.” “May his spirit live in his students and co-workers,” wrote Lorenz, “and may the seeds he sowed bear rich fruit! ...I will forever remember and honor this noble man and talented researcher.”

“Peter Nikolaevich,” wrote N.A. Kaptsov, “left behind a school of physicists, and, moreover, a school not formally expressed in the fact that this or that Soviet physicist was once a student of Lebedev, but a wide real school, living and growing. This school manifests its existence in the development of those areas of physics, the deep research of which Pyotr Nikolaevich encouraged his immediate students to engage in in the Stoletov laboratory and “Lebedev’s basement”... The students and students of P. N. Lebedev’s students are continuously preparing physicists who meet Lebedev’s precepts and capable of satisfying the needs of the country - the needs of the national economy... The role of all the activities of Pyotr Nikolaevich Lebedev in the matter of personnel training is truly great.”

“The example of the Lebedev laboratory with numerous students and employees,” says S.I. Vavilov, “served as the basis for the creation of a number of research physics institutes in our country immediately after the October Socialist Revolution opened up opportunities for this. It can even be argued that, in general, our entire modern huge network of research institutions in any specialty owes its implementation to a certain extent to Lebedev’s example. Before Lebedev, Russia did not suspect the possibility of collective scientific research in large laboratories... Naturally, physical institutes were the first to arise; it was easiest for them to rely on Lebedev’s example. And others followed the physicists.”

What about the scientific heritage of P. N. Lebedev? What is his fate? In an article dedicated to the memory of the great scientist, S. I. Vavilov wrote: “If you open the volume of the works of P. N. Lebedev, in which all his scientific works occupy only about 200 pages, and look through these works one after another, starting from “Measurement dielectric constant vapors" (1891) and ending with the "Magnetometric study of rotating bodies" (1911), then we see an amazing chain of experimental works, the significance of which not only has not yet become a part of history, but is revealed and growing every year. This is indisputable in relation to all work on the pressure of light, on ultrashort electric waves, on ultrasonic waves, on the dielectric constants of vapors and on the mechanism of terrestrial magnetism. Not only a historian, but also a physicist researcher will for a long time resort to the works of P. N. Lebedev as a living source. Lebedev’s works is a book about which Fet’s words can be repeated:

Petr Nikolaevich Lebedev

Experimental physicist.

The father actively prepared his son for a career. He chose the best educational institution for this - the German Peter and Paul School, and taught his son to sports from childhood, but Lebedev actively did not want to give his future to trading. “I feel a grave chill at the mere thought of the career for which I am being prepared - to sit for an unknown number of years in a stuffy office on a high stool, over open volumes, mechanically copying letters and numbers from one paper to another, and so on all my life...” he wrote down. it's in the diary. “They want to send me by force to a place where I’m not fit at all.”

In 1884, Lebedev graduated from the Khainovsky Real School.

Lebedev was most interested in physics, but he could not enter the university. The right to enter the university at that time was given only by classical education, that is, a gymnasium in which ancient languages ​​were taught, primarily Latin.

Having decided to achieve his goal, Lebedev left for Germany.

In Germany, for several years he studied in the physics laboratories of the famous physicist August Kundt - first at the University of Strasbourg (1887–1888), then at the University of Berlin (1889–1890). However, from the University of Berlin, Kundt sent Lebedev back to Strasbourg, because in Berlin Lebedev could not defend his dissertation, all because of the same ignorance of the Latin language.

Lebedev completed his dissertation in Strasbourg. It was called “On the measurement of dielectric constants of water vapor and on the Mossotti-Clausius theory of dielectrics.” Many provisions of this work by Lebedev remain relevant today.

In his diary that year, Lebedev wrote:

“...People are like swimmers: some swim on the surface and surprise spectators with their flexibility and speed of movement, doing it all for exercise; others dive deep and come out either empty-handed or with pearls - endurance and happiness are necessary for the latter.”

But, in addition to such purely emotional ones, Lebedev wrote down thoughts that even now cannot help but amaze.

“...Each atom of each of our primary elements represents a complete solar system, that is, it consists of various atomic planets rotating at different speeds around the central planet or in some other way moving characteristically periodically. Periods of movement are very short-lived (according to our concepts)..."

The recording was made by Lebedev on January 22, 1887, that is, many years before the planetary model of the atom was developed by E. Rutherford and N. Bohr.

In Strasbourg, Lebedev first drew attention to comet tails.

They interested him, first of all, from the point of view of light pressure.

Kepler and Newton also assumed that the reason for the deviations of cometary tails from the Sun could be the mechanical pressure of light. But it was extremely difficult to carry out such experiments. Before Lebedev, this problem was dealt with by Euler, Fresnel, Bredikhin, Maxwell, and Boltzmann. The great names did not bother the young researcher. Already in 1891, in a note “On the repulsive force of ray-emitting bodies,” he tried to prove that in the case of very small particles the repulsive force of light pressure must undoubtedly exceed Newtonian attraction; thus, the deflection of cometary tails is actually caused by light pressure.

“It seems that I have made a very important discovery in the theory of the movement of luminaries, especially comets,” Lebedev joyfully told one of his colleagues.

In 1891, full of ideas, Lebedev returned to Russia.

The famous physicist Stoletov gladly invited Lebedev to Moscow University. There, for several years, Lebedev’s work “Experimental study of the ponderomotive effect of waves on resonators” was published in separate issues. The first part of the work was devoted to the experimental study of the interactions of electromagnetic resonators, the second - hydrodynamic, and the third - acoustic. The merits of the work turned out to be so undoubted that Lebedev was awarded a doctorate without preliminary defense and relevant exams - a very rare case in the practice of Russian universities.

“The main interest of studying the pondemotor action of wave-like motion,” Lebedev wrote, “lies in the fundamental possibility of extending the found laws to the region of light and thermal emission of individual molecules of bodies and pre-calculating the resulting intermolecular forces and their magnitude.”

The movement of light and heat waves, which Lebedev wrote about, was studied by him using models. Even then, Lebedev came close to trying to overcome the numerous difficulties in detecting and measuring the pressure of light, which his famous predecessors could not overcome. But success came to Lebedev only in 1900.

The device on which Lebedev obtained the results looked simple.

The light from the voltaic spirit fell on a light wing suspended on a thin thread in a glass container from which the air had been pumped out. The light pressure could be judged by the slight twisting of the thread. The wing itself consisted of two pairs of thin platinum circles. One of the circles of each pair was shiny on both sides, while the others had one side covered with platinum niello. In order to eliminate the movement of gas that occurs when the temperatures of the wing and the glass container differ, the light was directed first to one side or the other of the wing. As a result, the radiometric effect could be taken into account by comparing the result when light falls on a thick and thin blackened circle.

Experiments in detecting and measuring light pressure brought Lebedev worldwide fame. The famous English physicist Lord Kelvin told Timiryazev when they met: “I have been at war with Maxwell all my life, not recognizing his light pressure! But your Lebedev made me give up.” Lebedev was elected extraordinary professor at Moscow University. However, even this was not without discussion: can an internationally recognized scientist occupy such a high position without knowing Latin? Not everyone was sure of this: Lebedev was elected with a margin of only three balls.

Unfortunately, in those same years, the first signs of a terrible heart disease appeared, which ultimately killed Lebedev.

“...As you can see, I am far away, in Heidelberg,” he wrote on April 10, 1902 to his close long-time friend Princess M.K. Golitsina. “On my way to the South, I intended to stop here for a few days, but illness tied me down for the whole winter. From personal experience I had to see how powerless medicine is in any difficult cases: the great Erb consoles me with the fact that suffering is “nervous” (what “nervous” means is unknown to anyone) and what it can do over time (with what time? 1000 years? ) completely pass. Now I feel better, dull despair has been replaced by a faint hope that things will improve enough that I will be able to work again. During the winter I had to endure very severe torment - it was not life, but some kind of long, intolerable dying; the pain has dulled all interests (not to mention the inability to work); Add to this the painful moral consciousness that I am completely in vain tormenting my sister because I can neither recover nor die - and you will see that I did not live this year cheerfully.

As you know, princess, there were so few joys in my personal life that I don’t feel sorry for parting with this life (I say this because I know what it means to die: last spring I completely “accidentally” experienced a severe heart attack) - I It’s just a pity that a very good machine for studying nature, useful to people, perishes with me: I must take my plans with me, since I cannot bequeath to anyone either my great experience or my experimental talent. I know that in twenty years these plans will be implemented by others, but what does it cost science to be twenty years late? And this consciousness that the solution to some important issues is close, that I know the secret of how they need to be solved, but am powerless to convey them to others - this consciousness is more painful than you think ... "

Nevertheless, Lebedev continued to work.

For cosmic phenomena, he believed, the main importance should not be the pressure on solid bodies, but the pressure on rarefied gases consisting of isolated molecules. At that time, very little was known about the structure of molecules and their optical properties. It was not even clear how, in fact, one should move from pressure on individual molecules to pressure on the body as a whole. The famous Swedish researcher Svante Arrhenius, for example, argued that gases, in principle, cannot experience light pressure. He put forward the so-called “drop” theory of the structure of cometary tails. According to Arrhenius's theory, the tails of comets could consist of tiny droplets formed by the condensation of hydrocarbons evaporating from the mysterious bowels of the comet. Astronomer K. Schwarzschild substantiated Arrhenius's opinion theoretically.

An attempt to solve the problem, which gave rise to many of the most controversial hypotheses and theories, took Lebedev almost ten years.

But he solved this problem.

In the device built by Lebedev, the gas under the pressure of absorbed light received a rotational motion, transmitted to a small piston, the deviations of which could be measured by the displacement of the mirror “bunny”. This time the thermal effect was overcome by the ingenious technique of adding hydrogen gas to the test gas. Hydrogen is an excellent conductor of heat; it instantly equalized all temperature inhomogeneities in the vessel.

“Dear colleague!

I still remember well how doubtful I was in 1902 about your intention to measure the pressure of radiation on gases, and with all the greater admiration I read now how you overcame all the obstacles. Thank you very much for your article. It came just at the moment when I was writing a small article in which I proved the superiority of the “resonator theory” of comet tails over Arrhenius’ “droplet theory”... Since now there is no longer any doubt that radiation pressure and light diffusion are related by the Fitzgerald relation, then attention should now be directed to the study of the resonant glow of extremely rarefied gases ... "

Inspired by the results obtained, Lebedev was ready to build on his success.

“...You, princess,” he wrote to Golitsyna, “have a sixth sense. Really, I’m in love with my science again, in love like a boy, just like before: I’m so carried away now, I work all day long, as if I wasn’t sick - again I’m the same as I was before: I feel my mental strength and freshness , I play with difficulties, I feel that I am Cyrano de Bergerac in physics, and therefore I can, and I want, and I will write to you: now I have a moral (i.e., male) right to do this. And I know that you not only forgave me - more: I feel that you are happy in a way that only a woman can and can be happy - and not just any woman.

But let me be even more selfish and start writing to you about what I invented, what I am doing now.

Of course, the idea is very simple: for some reasons, which I will not dwell on, I came to the conclusion that all rotating bodies must be magnetic - the peculiarity that our Earth is magnetic and attracts the blue end of the magnetic compass needle to the north pole is due precisely by rotating it around an axis. But this is just an idea - experience is needed, and now I am preparing it: I will take an axis that makes more than a thousand revolutions per second - I am currently busy with the design of this device - on the axis I will place balls three centimeters in diameter from various substances : copper, aluminum, cork, glass, etc. - and I will set it into rotation; they must become magnetic just like the Earth; To make sure of this, I will take a tiny magnetic needle - only two millimeters in length - and hang it on the thinnest quartz thread - then its end should be attracted to the pole of the rotating ball.

And now I’m like Faust in the first act before a charming vision: like Margarita’s spinning wheel, my axle hums, I see the thinnest quartz threads... To complete the picture, only Margarita is missing... But the main thing here is not even the axles and not the threads, but the feeling of joy of life, thirst to capture every moment, the feeling of your purpose, your value for someone and for something, a bright warm ray that penetrates your entire soul..."

In 1911, together with other famous scientists, Lebedev left Moscow University in protest against the actions of the Minister of Education L. A. Kasso.

This decision cost Lebedev great suffering.

Most of all, he was afraid that leaving the university would destroy the school of Russian physicists he had carefully and painstakingly created.

This, fortunately, did not happen.

Lebedev's students and followers - P. P. Lazarev, S. I. Vavilov, V. K. Arkadyev, A. R. Kolli, T. P. Kravets, V. D. Zernov, A. B. Mlodzeevsky, N. A Kaptsov, N.N. Andreev - made a huge contribution to science.

Lebedev was extremely sorry to leave the physics laboratory he created. A brilliant experimenter, he now did not have the opportunity to carry out the complex experiments he had planned. However, Lebedev refused a very flattering invitation from Svante Arrhenius to move to Stockholm. “Naturally,” Arrhenius wrote to Lebedev, “it would be a great honor for the Nobel Institute if you wished to settle and work there, and we, without a doubt, would provide you with all the necessary funds so that you would have the opportunity to continue working... You, of course , would receive a completely free position, as it corresponds to your rank in science ... "

Leaving the laboratory, Lebedev transferred experimental work to a private apartment rented in the basement of house number 20 on Mertvy Lane.

“...I am writing to you, princess, just to you – a few lines.

It’s so hard for me, it’s night all around, there’s silence, and I really want to clench my teeth tighter and groan. What's happened? - you ask. Yes, nothing unusual: just the building of personal life, personal happiness - no, not happiness, but the joy of life - was built on sand, now it has cracked and will probably collapse soon, and the strength to build a new one, even the strength to level a new place - no, no faith, no hope.

My head is full of scientific plans, witty works are in progress; I haven’t said my last word yet - I understand this intellectually, I understand intellectually the words “duty”, “care”, “get over it” - I understand everything, but the horror, the horror of a hateful, hateful life beats me with a fever. Old, sick, lonely, I know the feeling of being close to death, I experienced it second by second in absolutely clear consciousness during one heart attack (the doctor didn’t think I would survive either) - I know this terrible feeling, I know what it means to prepare for it step by step, I know that this is not a joke - and now, if now, as then, here, when I am writing to you, death were to approach me again, I would not now interfere, but would go to meet it halfway - it is so clear to me that my life is over..."

“The abundance of thoughts and projects,” Lebedev wrote to one of his friends, “does not give me quiet time for work: it seems that what you are doing has already been done, but what has been created is important, more important than the previous one and requires the fastest possible implementation - my hands involuntarily give up, and there is a crush, and the results, instead of raining down, do not move..."

The work begun by Lebedev was completed by physicist A. Compton, who finally solved the problems of light pressure.