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BIOGRAPHIES OF GREAT SCIENTISTS
Thomson Joseph John. Biography of a scientist
Directory / Biographies of great scientists
The English physicist Joseph Thomson entered the history of science as the man who discovered the electron. Once he said: "Discoveries are due to the sharpness and power of observation, intuition, unshakable enthusiasm until the final resolution of all the contradictions that accompany pioneer work." Joseph John Thomson was born December 18, 1856 in Manchester. Here, in Manchester, he graduated from Owens College, and in 1876-1880 he studied at the University of Cambridge at the famous Trinity College (Trinity College). In January 1880, Thomson successfully passed the final exams and began working at the Cavendish Laboratory. His first article, published in 1880, was devoted to the electromagnetic theory of light. The following year, two papers appeared, one of which laid the foundation for the electromagnetic theory of mass. The article was titled "On Electric and Magnetic Effects Produced by the Motion of Electrified Bodies". This article expresses the idea that "the ether outside a charged body is the carrier of all mass, momentum and energy." With an increase in speed, the nature of the field changes, due to which all this "field" mass increases, remaining all the time proportional to the energy. Thomson was obsessed with experimental physics in the best sense of the word. Tireless at work, he was so accustomed to achieving his goal on his own that evil tongues spoke of his complete disregard for authorities. It was said that he preferred to independently think through any questions of a scientific nature unfamiliar to him, instead of turning to books and ready-made theories. However, this is clearly an exaggeration... Thomson's scientific achievements were highly appreciated by Rayleigh, director of the Cavendish laboratory. Leaving in 1884 as director, he did not hesitate to recommend Thomson as his successor. For Joseph himself, his appointment was a surprise. It is known that when one of the American physicists who was a trainee at the Cavendish Laboratory found out about this appointment, he immediately packed up his belongings. "It makes no sense to work under a professor who is only two years older than you..." - he said, sailing home. Well, he had plenty of time ahead of him to regret his haste. The old director of the laboratory had good reasons for such a choice. Everyone who knew Thomson closely unanimously noted his unfailing benevolence and pleasant manner of communication, combined with principles. Later, the students recalled that their supervisor liked to repeat Maxwell's words that one should never dissuade a person from doing an experiment he had conceived. Even if he does not find what he is looking for, he may discover something else and benefit more than from a thousand discussions. So different properties coexisted in this person, such as the independence of one's own judgments and deep respect for the opinion of a student, employee or colleague. And perhaps it was these qualities that ensured his success as head of the Cavendish. Thomson came to the new post with published works, conviction in the unity of the material world and many plans for the future. And his early successes contributed to the credibility of the Cavendish Laboratory. Soon a group of young people from various countries gathered here. All of them equally burned with enthusiasm and were ready for any sacrifice for the sake of science. A school was formed, a real scientific team of people united by a common goal and methods, with world authority at the head. From 1884 to 1919, when Rutherford succeeded him as director of the laboratory, Thomson directed the Cavendish laboratory. During this time it has become a major center of world physics, an international school of physicists. Rutherford, Bohr, Langevin and many others, including Russian scientists, began their scientific journey here. Completing the book of his memoirs at the end of his life, Thomson lists among his former doctoral students 27 members of the Royal Society, 80 professors who successfully work in thirteen countries. The result is truly brilliant. Thomson's research program was broad: questions of the passage of electric current through gases, the electronic theory of metals, the study of the nature of various kinds of rays ... Taking up the study of cathode rays, Thomson first of all decided to check whether his predecessors, who had achieved the deflection of rays by electric fields, had carried out the experiments with sufficient care. He conceives a repeated experiment, designs special equipment for it, monitors the accuracy of the execution of the order himself, and the expected result is obvious. In the tube designed by Thomson, the cathode rays obediently attracted to the positively charged plate and clearly repelled from the negative one, that is, they behaved as a stream of fast-moving tiny corpuscles charged with negative electricity was supposed to. Excellent result! He could, of course, put an end to all disputes about the nature of cathode rays, but Thomson did not consider his research completed. Having determined the nature of the rays qualitatively, he wanted to give an exact quantitative definition of the corpuscles that make them up. Inspired by the first success, he designed a new tube: a cathode, accelerating electrodes in the form of rings and plates, to which a deflecting voltage could be applied. On the wall opposite the cathode, he deposited a thin layer of a substance capable of glowing under the impact of incident particles. It turned out to be the ancestor of cathode ray tubes, so familiar to us in the age of televisions and radars. The purpose of Thomson's experiment was to deflect a bunch of corpuscles with an electric field and compensate for this deflection with a magnetic field. The conclusions he came to as a result of the experiment were amazing. First, it turned out that the particles fly in the tube with enormous velocities close to the speed of light. And secondly, the electric charge per unit mass of corpuscles was fantastically large. What kind of particles were these: unknown atoms carrying huge electrical charges, or tiny particles with negligible mass, but with a smaller charge? Further, he discovered that the ratio of specific charge to unit mass is a constant value, independent of the particle velocity, or of the cathode material, or of the nature of the gas in which the discharge occurs. Such independence was alarming. It seems that corpuscles were some kind of universal particles of matter, constituents of atoms... At the mere thought of this, a researcher of the last century should have become uneasy. After all, the very word "atom" meant "indivisible". For thousands of years that have passed since the time of Democritus, atoms have been symbols of the limit of divisibility, symbols of the discreteness of matter. And suddenly ... Suddenly it turns out that they also have components? Agree that there was something to feel confused. True, the horror of sacrilege was mixed to a large extent with the delight of anticipation of the great discovery ... Thomson set to work. First of all, it was necessary to determine the parameters of the mysterious corpuscles, and then, perhaps, it would be possible to decide what they were. The thin handwriting of the scientist covers sheets of paper with endless figures. And here they are, the first results of the calculations: there is no doubt, unknown particles are nothing but the smallest electric charges, indivisible atoms of electricity, or electrons. They were known theoretically and even received a name, but only he managed to discover and thereby finally confirm their existence experimentally. And he did it - the stubborn English experimental physicist Professor Joseph John Thomson, whom his students and colleagues behind his back called simply GJ. On April 29, 1897, in the room where the meetings of the Royal Society of London had been held for more than two hundred years, his report was scheduled. Most of those present are well aware of the history of the issue. Many themselves have tried to solve the problems of the nature of cathode rays. The speaker's name promised an interesting message. And here is Thomson on the podium. He is tall, thin, and wears metal-rimmed glasses. He speaks confidently and loudly. The speaker's assistants immediately, in front of those present, are preparing a demonstration experiment. Indeed, everything the tall bespectacled gentleman was talking about happened. The cathode rays in the tube obediently deflected and attracted magnetic and electric fields. Moreover, they were deflected and attracted exactly as they should, if we assume that they consisted of the smallest negatively charged particles ... The listeners were delighted. They repeatedly interrupted the report with applause. The final exceeded all expectations. This ancient hall, perhaps, has never seen such a triumph. Honorable members of the Royal Society jumped up from their seats, hurried to the demonstration table, crowded, waving their arms, and shouted ... The delight of those present was not at all due to the fact that colleague J. J. Thomson had so convincingly revealed the true nature of cathode rays. The matter was much more serious. Atoms, the first building blocks of matter, ceased to be elementary round grains, impenetrable and indivisible particles without any internal structure ... If negatively charged corpuscles could fly out of them, then atoms must have been some kind of complex system consisting of something charged positive electricity and from negatively charged corpuscles - electrons. The name "electron", once proposed by Stoney to denote the magnitude of the smallest electric charge, became the name of the indivisible "atom of electricity." Now the most necessary directions of future searches have become visible. First of all, of course, it was necessary to accurately determine the charge and mass of one electron, which would make it possible to clarify the masses of atoms of all elements, calculate the masses of molecules, give recommendations for the correct preparation of reactions ... What can I say, knowledge of the exact value of the charge of an electron was necessary like air, and therefore, many physicists immediately took up experiments to determine it. In 1904, Thomson published his new model of the atom. It was also a sphere uniformly charged with positive electricity, inside which negatively charged corpuscles rotated, the number and arrangement of which depended on the nature of the atom. The scientist failed to solve the general problem of a stable arrangement of corpuscles inside the sphere, and he settled on a particular case when the corpuscles lie in the same plane passing through the center of the sphere. In each ring, the corpuscles made rather complex movements, which the author of the hypothesis associated with the spectra. And the distribution of corpuscles along the shell rings corresponded to the vertical columns of the periodic table. They say that once journalists asked GJ to clearly explain how he suggests the structure of "his atom". “Oh, it’s very simple,” the professor replied calmly, “most likely, it’s something like a pudding with raisins ... So the Thomson atom entered the history of science - a positively charged "pudding" stuffed with negative "raisins" - electrons. Thomson himself was well aware of the complexity of the "raisin pudding" structure. The scientist came very close to the conclusion that the nature of the distribution of electrons in an atom determines its place in the periodic system of elements, but only came up. The final conclusion was yet to come. Much of the model he proposed was still inexplicable. No one, for example, understood what the positively charged mass of an atom was and how many electrons should be contained in the atoms of various elements. Thomson taught physicists how to control electrons, and this is his main merit. The development of the Thomson method forms the basis of electron optics, vacuum tubes, and modern particle accelerators. Thomson was awarded the Nobel Prize in Physics in 1906 for his study of the passage of electricity through gases. Thomson also developed methods for studying positively charged particles. His monograph Rays of Positive Electricity, published in 1913, marked the beginning of mass spectroscopy. Developing Thomson's technique, his student Aston built the first mass spectrometer and developed a method for the analysis and separation of isotopes. In Thomson's laboratory, the first measurements of the elementary charge began from observing the motion of a charged cloud in an electric field. This method was further improved by Millikan and led to his now classic measurements of the electron charge. The famous cloud chamber, built by Thomson's student and collaborator Wilson in 1911, began its life in the Cavendish laboratory. Thus, the role of Thomson and his students in the formation and development of atomic and nuclear physics is very great. But Thomson until the end of his life remained a supporter of the ether, developed models of movement in the ether, the result of which, in his opinion, were the observed phenomena. Thus, he interpreted the deflection of the cathode beam in a magnetic field as the precession of a gyroscope, endowing the combination of electric and magnetic fields with a rotational moment. Thomson died on August 30, 1940, at a difficult time for England, when the threat of an invasion by the Nazis hung over her. Author: Samin D.K.
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