Hendrik Anton Lorenz what he discovered. The man who created the electron theory

Lorenz Hendrik Anton
Born: July 18, 1853.
Died: February 4, 1928 (age 74).

Biography

Hendrik (often spelled Hendrik) Anton Lorentz (Dutch: Hendrik Antoon Lorentz; July 18, 1853, Arnhem, Netherlands - February 4, 1928, Haarlem, Netherlands) - Dutch theoretical physicist, winner of the Nobel Prize in Physics (1902, jointly with Pieter Zeeman) and other awards, member of the Royal Netherlands Academy of Sciences (1881), a number of foreign academies of sciences and scientific societies.

Lorentz is best known for his work in the fields of electrodynamics and optics. Combining the concept of a continuous electromagnetic field with the idea of discrete electric charges that make up matter, he created the classical electronic theory and applied it to solve many particular problems: he obtained an expression for the force acting on a moving charge from the electromagnetic field (Lorentz force), and derived formula connecting the refractive index of a substance with its density (Lorentz-Lorentz formula), developed the theory of light dispersion, explained a number of magneto-optical phenomena (in particular, the Zeeman effect) and some properties of metals. Based on electronic theory, the scientist developed the electrodynamics of moving media, including putting forward a hypothesis about the contraction of bodies in the direction of their movement (Fitzgerald - Lorentz contraction), introduced the concept of “local time”, obtained a relativistic expression for the dependence of mass on speed, and derived relationships between coordinates and time in inertial reference systems moving relative to each other (Lorentz transformations). Lorentz's work contributed to the formation and development of the ideas of the special theory of relativity and quantum physics. In addition, he obtained a number of significant results in the thermodynamics and kinetic theory of gases, the general theory of relativity, and the theory of thermal radiation.

Origin and childhood (1853-1870)

Hendrik Anton Lorenz was born on July 15, 1853 in Arnhem. His ancestors came from the Rhine region of Germany and were mainly engaged in agriculture. The father of the future scientist, Gerrit Frederik Lorentz (1822-1893), owned a fruit tree nursery near Velp. Hendrik Anton's mother, Gertrude van Ginkel (Geertruida van Ginkel, 1826-1861), grew up in Renswoude in the province of Utrecht, was married, widowed early, and in the third year of widowhood she married a second time - to Gerrit Frederick. They had two sons, but the second of them died in infancy; Hendrik Anton was brought up together with Hendrik Jan Jakob, Gertrude's son from his first marriage. In 1862, after the early death of his wife, the father of the family married Luberta Hupkes (1819/1820-1897), who became a caring stepmother for the children.

At the age of six, Hendrik Anton entered Timmer Primary School. Here, in the lessons of Gert Cornelis Timmer, the author of textbooks and popular science books on physics, young Lorenz became acquainted with the basics of mathematics and physics. In 1866, the future scientist successfully passed the entrance exams to the newly opened Higher Civil School (Dutch Hogereburgerschool) in Arnhem, which roughly corresponded to a gymnasium. Studying was easy for Hendrik Anton, which was facilitated by the pedagogical talent of teachers, primarily H. Van der Stadt, the author of several famous textbooks on physics, and Jacob Martin van Bemmelen, who taught chemistry. As Lorenz himself admitted, it was Van der Stadt who instilled in him a love of physics. Another important meeting in the life of the future scientist was his acquaintance with Herman Haga, who studied in the same class and later also became a physicist; they remained close friends throughout their lives. In addition to the natural sciences, Hendrik Anton was interested in history, read a number of works on the history of the Netherlands and England, and was fond of historical novels; in literature he was attracted by the work of English writers - Walter Scott, William Thackeray and especially Charles Dickens. Distinguished by his good memory, Lorenz studied several foreign languages (English, French and German), and before entering the university he independently mastered Greek and Latin. Despite his sociable character, Hendrik Anton was a shy person and did not like to talk about his experiences even with his loved ones. He was alien to any mysticism and, according to his daughter, “was deprived of faith in God’s grace... Belief in the highest value of reason... replaced his religious beliefs.”

Studying at the University. First steps in science (1870-1877)

In 1870, Lorenz entered the University of Leiden, the oldest university in Holland. Here he attended lectures by physicist Pieter Rijke and mathematician Pieter van Geer, who taught a course in analytical geometry, but became closest to astronomy professor Frederick Kaiser, who learned about a new talented student from his former student Van der Stadt. It was while studying at the university that the future scientist became acquainted with the fundamental works of James Clerk Maxwell and, with some difficulty, was able to understand them, which was facilitated by the study of the works of Hermann Helmholtz, Augustin Fresnel and Michael Faraday. In November 1871, Lorenz passed his master's degree exams with honors and, deciding to prepare for the doctoral exams on his own, left Leiden in February 1872. Returning to Arnhem, he became a mathematics teacher at evening school and at Timmer's school, where he had once studied; this job left him enough free time to do science. The main direction of Lorentz's research was Maxwell's electromagnetic theory. In addition, in the school laboratory he performed optical and electrical experiments and even unsuccessfully tried to prove the existence of electromagnetic waves by studying the discharges of a Leyden jar. Subsequently, touching on the famous work of the British physicist, Lorentz said: “His “Treatise on Electricity and Magnetism” made on me, perhaps, one of the strongest impressions in my life; the interpretation of light as an electromagnetic phenomenon surpassed in its boldness everything that I had known so far. But Maxwell's book was not an easy one! Written in the years when the scientist’s ideas had not yet received final formulation, it did not represent a complete whole and did not answer many questions.”

In 1873, Lorenz passed his doctoral exams, and on December 11, 1875 in Leiden, with honors (magna cum laude), he defended his doctoral dissertation “On the Theory of Reflection and Refraction of Light” (Dutch: Over de theorie der terugkaatsing en breking van het licht), in which gave an explanation of these processes based on Maxwellian theory. After his defense, the young doctor of science returned to his former life as an Arnhem teacher. In the summer of 1876, together with friends, he hiked through Switzerland. By this time, he was faced with the question of completely switching to mathematics: it was this discipline that he successfully taught at school, and therefore Utrecht University offered him the position of professor of mathematics. However, Lorenz, hoping to return to his alma mater, rejected this offer and decided to take a position as a teacher at the Leiden classical gymnasium as a temporary position. Soon an important change took place at Leiden University: the department of physics was divided into two parts - experimental and theoretical. The new position of professor of theoretical physics was first offered to Jan Diederik van der Waals, and when he refused, Lorentz was appointed to this position. It was the first department of theoretical physics in the Netherlands and one of the first in Europe; Lorentz's successful work in this field contributed to the formation of theoretical physics as an independent scientific discipline.

Professor in Leiden (1878-1911)

On January 25, 1878, Lorenz officially assumed the title of professor, delivering an inaugural speech and report “Molecular Theories in Physics.” According to one of his former students, the young professor “possessed a peculiar gift, despite all his kindness and simplicity, of maintaining a certain distance between himself and his students, without at all striving for it and without noticing it.” Lorenz's lectures were popular among students; he enjoyed teaching, despite the fact that this activity took up a significant portion of his time. Moreover, in 1883 he took on an additional load by replacing his colleague Heike Kamerlingh Onnes, who, due to illness, was unable to teach a course in general physics at the Faculty of Medicine; Lorenz continued to give these lectures even after Onnes's recovery, until 1906. Based on the courses of his lectures, a series of well-known textbooks were published, which were reprinted several times and were translated into many languages. In 1882, Professor Lorenz began his popularization activities, his speeches to a wide audience were a success due to his talent for presenting complex scientific issues in an accessible and clear manner.

In the summer of 1880, Lorenz met Aletta Catharina Kaiser (1858-1931), the niece of Professor Kaiser and the daughter of the famous engraver Johann Wilhelm Kaiser, director of the Rijksmuseum in Amsterdam. The engagement took place that same summer, and early next year the young people got married. In 1885, their daughter Gertrude Luberta (Dutch: Geertruida de Haas-Lorentz) was born, who received names in honor of the scientist’s mother and stepmother. That same year, Lorenz bought a house at 48 Heugracht, where the family led a quiet, measured life. In 1889, a second daughter, Johanna Wilhelmina, was born, in 1893, a first son, who lived less than a year, and in 1895, a second son, Rudolf. The eldest daughter subsequently became a student of her father, studied physics and mathematics and was married to the famous scientist Vander Johannes de Haas, a student of Kamerlingh Onnes.

Lorenz spent his first years in Leiden in voluntary self-isolation: he published little abroad and practically avoided contact with the outside world (this was probably due to his shyness). His work was little known outside of Holland until the mid-1890s. Only in 1897 did he first attend the congress of German naturalists and doctors, held in Düsseldorf, and since then he became a regular participant in major scientific conferences. He met such famous European physicists as Ludwig Boltzmann, Wilhelm Wien, Henri Poincaré, Max Planck, Wilhelm Roentgen and others. Lorentz's recognition as a scientist also grew, which was facilitated by the success of the electronic theory he created, which complemented Maxwell's electrodynamics with the idea of “atoms of electricity,” that is, the existence of charged particles that make up matter. The first version of this theory was published in 1892; subsequently it was actively developed by the author and was used to describe various optical phenomena (dispersion, properties of metals, fundamentals of electrodynamics of moving media, and so on). One of the most striking achievements of electronic theory was the prediction and explanation of the splitting of spectral lines in a magnetic field, discovered by Pieter Zeeman in 1896. In 1902, Zeeman and Lorentz shared the Nobel Prize in Physics; The Leiden professor thus became the first theorist to receive this award. The success of the electronic theory was largely due to its author's sensitivity to various ideas and approaches, and his ability to combine elements of different theoretical systems. As historian Olivier Darrigol wrote,

As befitted the openness of his country, he read German, English and French sources indiscriminately. His main inspirations, Helmholtz, Maxwell and Fresnel, belonged to very different, sometimes incompatible traditions. While in the ordinary mind eclecticism might create confusion, Lorenz benefited from it.

Now Lorenz received invitations from various parts of the world to give special reports: he visited Berlin (1904) and Paris (1905), and in the spring of 1906 he gave a series of lectures at Columbia University in New York. Soon other universities began to lure him away; in particular, the University of Munich in 1905 offered him much more favorable conditions than in Leiden. However, the scientist was in no hurry to take off and give up a quiet life in a small town, and after the Dutch Ministry of Education significantly improved his working conditions (the lecture load was reduced, an assistant was allocated, a separate office and a personal laboratory), he finally abandoned thoughts of moving. In 1909, Lorentz was appointed chairman of the physics department of the Royal Netherlands Academy of Sciences, a position he held for twelve years.

The emergence of the theory of relativity and the first quantum ideas called into question the validity of Lorentz's electron theory and classical physics in general. The Dutch scientist tried to the last to find a way out of the impasse in which old physics found itself, but did not succeed. As Torichan Kravets wrote in the preface to the Soviet edition of Lorentz’s “Theory of Electrons,” “his struggle for his teaching is truly grandiose. The scientific impartiality of the author, who respectfully meets all objections and all difficulties, is also striking. Having read his book, you see with your own eyes that everything has been done to save the old customary views - and all this did not bring them salvation.” Despite his commitment to the ideals of the classics and a cautious approach to new concepts, Lorenz was clearly aware of the imperfection of old and the fruitfulness of new scientific concepts. In the autumn of 1911, the first Solvay Congress took place in Brussels, bringing together the leading European physicists to discuss the quantum theory of radiation. The chairman of this congress was Lorenz, whose candidacy turned out to be very successful due to his great authority, knowledge of several languages and ability to direct discussions in the right direction. Colleagues recognized his merits in holding the congress at a high scientific level; Thus, in one of his letters, Albert Einstein called Lorentz “a miracle of intelligence and tact.” But what impression did communication with the Dutch scientist make on Max Born: “What struck me most when looking at him was the expression in his eyes - an amazing combination of deep kindness and ironic superiority. His speech corresponded to this - clear, soft and convincing, but at the same time with ironic shades. Lorenz's behavior was endearingly kind..."

Haarlem (1912-1928)

In 1911, Lorenz received an offer to take up the post of curator of the Taylor Museum, which had a physics room with a laboratory, and of the Dutch Scientific Society (Koninklijke Hollandsche Maatschappij der Wetenschappen) in Haarlem. The scientist agreed and began to look for a successor to the position of Leiden professor. After the refusal of Einstein, who by that time had already accepted the invitation from Zurich, Lorentz turned to Paul Ehrenfest, who was working in St. Petersburg. In the autumn of 1912, when the latter's candidacy was officially approved, Lorenz finally moved to Haarlem. At the Taylor Museum he received a small laboratory for his personal use; His duties included organizing popular lectures for physics teachers, which he began to give himself. In addition, for another ten years he remained an extraordinary professor at Leiden University and every Monday at 11 a.m. he gave special lectures there on the latest physical ideas. This traditional seminar became widely known in the scientific world; it was attended by many famous researchers from different countries of the world.

As Lorenz grew older, he paid more and more attention to social activities, especially problems of education and international scientific cooperation. Thus, he became one of the founders of the first Dutch lyceum in The Hague and the organizer of the first free libraries and reading room in Leiden. He was one of the managers of the Solvay Fund, with whose funds the International Physical Institute was founded, and headed the committee in charge of distributing benefits for scientific research by scientists from various countries. In a 1913 article, Lorenz wrote: “It is universally recognized that cooperation and the pursuit of a common goal ultimately produces the precious sense of mutual respect, unity and good friendships, which in turn strengthen peace.” However, the First World War, which came soon, interrupted ties between scientists of the warring countries for a long time; Lorenz, as a citizen of a neutral country, tried to the best of his ability to smooth out these contradictions and restore cooperation between individual researchers and scientific societies. Thus, having entered the leadership of the International Research Council founded after the war (the predecessor of the International Council for Science), the Dutch physicist and his like-minded people achieved the exclusion from the charter of this organization of clauses that discriminated against representatives of the defeated countries. In 1923, Lorenz became a member of the International Committee on Intellectual Cooperation, established by the League of Nations to strengthen scientific ties between European states, and some time later replaced the philosopher Henri Bergson as chairman of this institution.

In 1918, Lorenz was appointed chairman of the state committee for draining the Zuiderzee Bay and until the end of his life he devoted a lot of time to this project, directly supervising engineering calculations. The complexity of the problem required taking into account numerous factors and the development of original mathematical methods; here the scientist’s knowledge in various fields of theoretical physics came in handy. Construction of the first dam began in 1920; the project ended many years later, after the death of its first leader. A deep interest in the problems of pedagogy led Lorenz to the board of public education in 1919, and in 1921 he headed the department of higher education in the Netherlands. The following year, at the invitation of the California Institute of Technology, the scientist visited the United States for the second time and gave lectures in a number of cities in this country. Subsequently, he traveled overseas twice more: in 1924 and in the fall-winter of 1926/27, when he gave a course of lectures in Pasadena. In 1923, upon reaching the age limit, Lorenz officially retired, but continued to give his Monday lectures as an emeritus professor. In December 1925, celebrations were held in Leiden to mark the 50th anniversary of Lorenz's defense of his doctoral dissertation. About two thousand people from all over the world were invited to this celebration, including many prominent physicists, representatives of the Dutch state, students and friends of the hero of the day. Prince Hendrick presented the scientist with Holland's highest award, the Grand Cross of the Order of Orange-Nassau, and the Royal Academy of Sciences announced the establishment of the Lorentz Medal for achievements in the field of theoretical physics.

Although his scientific productivity noticeably decreased, Lorentz continued to be interested in the development of physics and conduct his own research until the last days of his life. His special position in the scientific world - the position of “the elder of physical science,” as Ehrenfest put it - was recognized by his chairmanship of the post-war Solvay congresses, which played a large role in clarifying the complex problems of new physics. According to Joseph Larmore, "he was the ideal leader of any international congress, for he was the most knowledgeable and the quickest to grasp the essence of the matter of all modern physicists." According to Arnold Sommerfeld, Lorenz “was the oldest in age and the most flexible and versatile in mind.” In October 1927, the Dutch scientist presided over his last, fifth Solvay Congress, at which the problems of new quantum mechanics were discussed. That same year, the Zuiderzee calculations were completed, and Lorenz, who left the department of higher education, hoped to devote more time to science. However, in mid-January 1928, he fell ill with erysipelas, and his condition worsened every day. On February 4, the scientist died. The funeral took place in Haarlem on February 9 with a large crowd of people; As a sign of national mourning throughout the country, telegraph communications were stopped for three minutes at noon. Paul Ehrenfest, Ernest Rutherford, Paul Langevin and Albert Einstein gave funeral orations as representatives of their countries. In his speech, the latter noted:

He [Lorenz] created his life down to the smallest detail, just as one creates a precious work of art. His kindness, generosity and sense of justice, which never left him, together with a deep, intuitive understanding of people and situations, made him a leader wherever he worked. Everyone followed him with joy, feeling that he did not seek to rule over people, but to serve them.

Scientific creativity

Early work on the electromagnetic theory of light

By the beginning of Lorentz's scientific career, Maxwell's electrodynamics was able to fully describe only the propagation of light waves in empty space, while the question of the interaction of light with matter was still awaiting its solution. Already in the first works of the Dutch scientist, some steps were taken towards explaining the optical properties of matter within the framework of the electromagnetic theory of light. Based on this theory (more precisely, on its interpretation in the spirit of long-range action proposed by Hermann Helmholtz), in his doctoral dissertation (1875) Lorentz solved the problem of reflection and refraction of light at the interface between two transparent media. Previous attempts to solve this problem within the framework of the elastic theory of light, in which light is treated as a mechanical wave propagating in a special luminiferous ether, encountered fundamental difficulties. A method for eliminating these difficulties was proposed by Helmholtz in 1870; a mathematically rigorous proof was given by Lorentz, who showed that the processes of reflection and refraction of light are determined by four boundary conditions imposed on the electric and magnetic field vectors at the interface of the media, and derived from this the famous Fresnel formulas. Further in the dissertation, total internal reflection and optical properties of crystals and metals were considered. Thus, Lorentz's work contained the foundations of modern electromagnetic optics. What is equally important, here appeared the first signs of that peculiarity of Lorentz’s creative method, which Paul Ehrenfest expressed in the following words: “a clear division of the role that in each given case of optical or electromagnetic phenomena arising in a piece of glass or metal, the “ether” plays, on the one hand, and “weighty matter” on the other.” The distinction between ether and matter contributed to the formation of ideas about the electromagnetic field as an independent form of matter, as opposed to the previously existing interpretation of the field as a mechanical state of matter.

The previous results concerned the general laws of light propagation. In order to draw more specific conclusions about the optical properties of bodies, Lorentz turned to ideas about the molecular structure of matter. He published the first results of his analysis in 1879 in the work “On the relationship between the speed of propagation of light and the density and composition of the medium” (Dutch. Over het verband tusschen de voortplantingssnelheid van het licht en de dichtheid en samenstelling der middenstoffen, an abbreviated version was published in the following year in the German journal Annalen der Physik). Assuming that the ether inside a substance has the same properties as in free space, and that in each molecule, under the influence of an external electric force, an electric moment proportional to it is excited, Lorentz obtained the relationship between the refractive index n and the density of the substance \rho in the form \frac( n^2-1)((n^2+2) \rho)=\mathrm(const). This formula was obtained back in 1869 by the Danish physicist Ludwig Valentin Lorentz on the basis of the elastic theory of light and is now known as the Lorentz-Lorentz formula. Essential in the Dutch scientist’s derivation of this relationship was also taking into account (in addition to the electric field of the external light wave) the local field caused by the polarization of the substance. To do this, it was assumed that each molecule is located in a cavity filled with ether and subject to influence from other cavities. The constant on the right side of the formula is determined by the polarizability of the molecules and depends on the wavelength, that is, it characterizes the dispersion properties of the medium. This dependence actually coincides with the dispersion relation of Selmayer (1872), obtained within the framework of the theory of elastic ether. It was calculated by Lorentz based on the idea of the presence of an electric charge in a molecule, oscillating around the equilibrium position under the influence of an electric field. Thus, this work already contained a fundamental model of electronic theory - a charged harmonic oscillator.

Electronic theory

General scheme of the theory

By the early 1890s Lorenz finally abandoned the concept of long-range forces in electrodynamics in favor of short-range action, that is, the idea of the finite speed of propagation of electromagnetic interaction. This was probably facilitated by Heinrich Hertz's discovery of electromagnetic waves predicted by Maxwell, as well as by the lectures of Henri Poincaré (1890), which contained an in-depth analysis of the consequences of the Faraday-Maxwell theory of the electromagnetic field. And already in 1892, Lorentz gave the first formulation of his electronic theory.

Lorentz's electronic theory is a Maxwellian theory of the electromagnetic field, supplemented by the idea of discrete electric charges as the basis of the structure of matter. The interaction of the field with moving charges is the source of the electrical, magnetic and optical properties of bodies. In metals, the movement of particles generates an electric current, while in dielectrics, the displacement of particles from an equilibrium position causes electrical polarization, which determines the value of the dielectric constant of the substance. The first consistent presentation of the electronic theory appeared in the large work “Maxwell’s electromagnetic theory and its application to moving bodies” (French: La théorie électromagnétique de Maxwell et son application aux corps mouvants, 1892), in which Lorentz, among other things, obtained the formula in a simple form for the force with which the field acts on charges (Lorentz force). Subsequently, the scientist refined and improved his theory: in 1895 the book “An Experience in the Theory of Electrical and Optical Phenomena in Moving Bodies” (German: Versuch einer Theorie der electrischen und optischen Erscheinungen in bewegten Körpern) was published, and in 1909 the famous monograph “The Theory of Electrons” was published and its application to the phenomena of light and thermal radiation” (English: The theory of electrons and its applications to the phenomena of light and radiant heat), containing the most complete presentation of the issue. In contrast to the initial attempts (in the work of 1892) to obtain the basic relations of the theory from the principles of mechanics, here Lorentz already began with Maxwell’s equations for empty space (ether) and similar phenomenological equations valid for macroscopic bodies, and then raised the question of the microscopic mechanism of electromagnetic processes in matter. Such a mechanism, in his opinion, is associated with the movement of small charged particles (electrons) that are part of all bodies. Assuming the finite sizes of electrons and the immobility of the ether present both outside and inside the particles, Lorentz introduced into the vacuum equations terms responsible for the distribution and movement (current) of electrons. The resulting microscopic equations (Lorentz-Maxwell equations) are supplemented with an expression for the Lorentz force acting on particles from the electromagnetic field. These relationships underlie the electronic theory and make it possible to describe a wide range of phenomena in a unified way.

Although attempts to construct a theory explaining electrodynamic phenomena by the interaction of an electromagnetic field with moving discrete charges had been made earlier (in the works of Wilhelm Weber, Bernhard Riemann and Rudolf Clausius), Lorentz's theory was fundamentally different from them. If previously it was believed that charges act directly on each other, now it was believed that electrons interact with the medium in which they are located - the stationary electromagnetic ether, obeying Maxwell's equations. This idea of ether is close to the modern concept of the electromagnetic field. Lorentz made a clear distinction between matter and ether: they cannot impart mechanical motion to each other (“entrain”), their interaction is limited to the sphere of electromagnetism. The force of this interaction for the case of a point charge is called Lorentz, although similar expressions were previously obtained by Clausius and Heaviside from other considerations. One of the important and much discussed consequences of the non-mechanical nature of the influence described by the Lorentz force was its violation of the Newtonian principle of action and reaction. In Lorentz's theory, the hypothesis of dragging the ether by a moving dielectric was replaced by the assumption of the polarization of body molecules under the influence of an electromagnetic field (this was carried out by introducing the corresponding dielectric constant). It is this polarized state that is transferred when the object moves, which makes it possible to explain the appearance in this case of the so-called Fresnel drag coefficient, which reveals itself, for example, in the famous Fizeau experiment. In addition, the works of Lorentz (1904, 1909) contained the first clear and unambiguous formulation (as applied to classical electrodynamics) of the general position that is now known as gauge invariance and which plays an important role in modern physical theories.

Details regarding the emergence of Lorentz's electronic theory, its evolution and differences from theories put forward by other researchers (for example, Larmor) can be found in a number of special works.

Applications: optical dispersion and conductivity of metals

Applying his theory to various physical situations, Lorentz obtained a number of significant partial results. Thus, in his first work on electronic theory (1892), the scientist derived Coulomb’s law, an expression for the force acting on a current-carrying conductor, and the law of electromagnetic induction. Here he obtained the Lorentz-Lorentz formula using a technique known as the Lorentz sphere. To do this, the field was calculated separately inside and outside an imaginary sphere described around the molecule, and for the first time the so-called local field associated with the magnitude of polarization at the boundary of the sphere was explicitly introduced. The article “Optical phenomena due to the charge and mass of the ion” (Dutch Optische verschijnselen die met de lading en de massa der ionen in verband staan, 1898) presented the classical electronic theory of dispersion in a complete form close to the modern one. The main idea was that dispersion is the result of the interaction of light with oscillating discrete charges - electrons (in Lorentz's original terminology - “ions”). Having written down the equation of motion of an electron, which is subject to a driving force from the electromagnetic field, a restoring elastic force and a frictional force causing absorption, the scientist arrived at the well-known dispersion formula, which specifies the so-called Lorentzian form of the dependence of the dielectric constant on frequency.

In a series of papers published in 1905, Lorentz developed the electronic theory of conductivity of metals, the foundations of which were laid in the works of Paul Drude, Eduard Riecke and J. J. Thomson. The starting point was the assumption of the presence of a large number of free charged particles (electrons) moving in the spaces between the stationary atoms (ions) of the metal. Dutch physicist took into account the velocity distribution of electrons in a metal (Maxwell distribution) and, using statistical methods of the kinetic theory of gases (kinetic equation for the distribution function), derived a formula for specific electrical conductivity, and also gave an analysis of thermoelectric phenomena and obtained the ratio of thermal conductivity to electrical conductivity, which is generally consistent with Wiedemann-Franz law. Lorentz's theory was of great historical importance for the development of the theory of metals, as well as for kinetic theory, representing the first exact solution to a kinetic problem of this kind. At the same time, it could not provide exact quantitative agreement with experimental data; in particular, it did not explain the magnetic properties of metals and the small contribution of free electrons to the specific heat of the metal. The reasons for this were not only the neglect of vibrations of the ions of the crystal lattice, but also the fundamental shortcomings of the theory, which were overcome only after the creation of quantum mechanics.

Applications: Magneto-optics, Zeeman effect and electron discovery

Another area in which the electronic theory has found successful application is magnetooptics. Lorentz gave an interpretation to such phenomena as the Faraday effect (rotation of the plane of polarization in a magnetic field) and the magneto-optical Kerr effect (change in the polarization of light reflected from a magnetized medium). However, the most convincing evidence in favor of the electron theory was the explanation of the magnetic splitting of spectral lines, known as the Zeeman effect. The first results of experiments by Pieter Zeeman, who observed the broadening of the D-line of the sodium spectrum in a magnetic field, were reported to the Netherlands Academy of Sciences on October 31, 1896. A few days later, Lorentz, who was present at this meeting, gave an explanation for the new phenomenon and predicted a number of its properties. He pointed out the nature of the polarization of the edges of the broadened line when observed along and across the magnetic field, which was confirmed by Zeeman over the next month. Another prediction concerned the structure of the broadened line, which should actually be a doublet (two lines) when observed longitudinally and a triplet (three lines) when observed transversely. Using more advanced equipment, the following year Zeeman confirmed this conclusion of the theory. Lorentz's reasoning was based on the decomposition of the oscillations of a charged particle ("ion" in the then terminology of the scientist) near the equilibrium position into movement along the direction of the field and movement in a perpendicular plane. Longitudinal oscillations, which are not affected by the magnetic field, lead to the appearance of an unshifted emission line when viewed transversely, while oscillations in the perpendicular plane produce two lines shifted by eH/2mc, where H is the magnetic field strength, e and m are the charge and mass of the “ion”, c - speed of light in vacuum.

From his data, Zeeman was able to obtain the sign of the charge of the “ion” (negative) and the e/m ratio, which turned out to be unexpectedly large and did not allow the “ion” to be associated with ordinary ions, the properties of which were known from electrolysis experiments. As it turned out after the experiments of J. J. Thomson (1897), this ratio coincided with that for particles in cathode rays. Since these latter particles soon became known as electrons, Lorentz began to use this term instead of the word “ion” in his research in 1899. In addition, he was the first to estimate the charge and mass of the electron separately. Thus, the results of measurements of spectral line splitting and their theoretical interpretation provided the first estimate of the main parameters of the electron and contributed to the acceptance of ideas about these new particles by the scientific community. It is sometimes argued, not without reason, that Lorentz predicted the existence of the electron. Although the discovery of the Zeeman effect was one of the highest achievements of electronic theory, it soon showed its limitations. Already in 1898, deviations from the simple picture of the phenomenon constructed by Lorenz were discovered; the new situation was called the anomalous (complex) Zeeman effect. The scientist tried for many years to improve his theory to explain the new data, but failed. The mystery of the anomalous Zeeman effect was solved only after the discovery of electron spin and the creation of quantum mechanics.

Awards and Memberships

Nobel Prize in Physics (1902)
Rumfoord Medal (1908)
Franklin Medal (1917)
Copley Medal (1918)
Order of the Legion of Honor (1923)
Order of Orange-Nassau (1925)
Foreign member of the Royal Society of London (1905), the Paris Academy of Sciences (1910), the Royal Society of Edinburgh (1920), the USSR Academy of Sciences (1925), etc.
Honorary doctorates from the Technical High School in Delft (1918), the University of Cambridge (1923) and the University of Paris, the degree of Doctor of Medicine from the University of Leiden (1925), etc.

Memory

In 1925, the Royal Netherlands Academy of Sciences established the Lorentz Gold Medal, which is awarded every four years for achievements in the field of theoretical physics.
The lock system (Lorentzsluizen), which is part of the complex of structures of the Afsluitdijk dam, which separates the Zuiderzee Bay from the North Sea, bears the name of Lorentz.
Numerous objects (streets, squares, schools, etc.) in the Netherlands are named after Lorenz. In 1931, in Arnhem, in the Sonsbeek park, a monument to Lorenz by sculptor Oswald Wenckebach was unveiled. In Haarlem on Lorentz Square and in Leiden at the entrance to the Institute of Theoretical Physics there are busts of the scientist. There are memorial plaques on buildings associated with his life and work.
In 1953, on the occasion of the famous physicist's centenary, the Lorenz Scholarship was established for students from Arnhem studying at Dutch universities. At Leiden University, the Institute of Theoretical Physics (Instituut-Lorentz), the honorary chair (Lorentz Chair), which is occupied every year by one of the prominent theoretical physicists, and the international center for holding scientific conferences, are named after Lorentz.
One of the lunar craters is named after Lorentz.

LORENZ HENDRIK ANTON

(1853 – 1928)

The outstanding Dutch theoretical physicist Hendrik Anton Lorenz was born on July 18, 1853 in Arnhem (Netherlands) in the family of Gerrit Frederick Lorenz and Gertrude Lorenz (née van Ginkel).

The father of the future scientist ran a kindergarten. His mother died when the boy was 4 years old, and five years later his father married Luberta Hupkes.

As a child, Hendrik Anton was a fragile and insecure boy. At the age of six he was sent to study at one of the best primary schools in Arnhem, and after a while he became the best student in his class.

In 1966, the Higher Civil School opened in Arnhem, and Hendrik Lorenz, as a gifted child, was immediately taken to the third grade.

At school, the boy, who was not in good health, caught everything on the fly. The future scientist was especially fascinated by the study of physics and mathematics. Having an excellent memory inherited from his grandfather, Hendrik Anton studied English, French, German, Greek and Latin. Lorenz wrote beautiful poetry in Latin until his death.

Success in his studies gave rise to a further desire in the young man to study. After graduating from the 5th grade of the Higher Civil School, Hendrik spent a year studying the works of the classics. And in 1870, the future scientist entered the prestigious Leiden University. Here he was most interested in the lectures on theoretical astronomy by Professor Frederick Kaiser, but his imagination was shocked by the works of James Clerk Maxwell, which had just entered the university library.

Maxwell's famous Treatise on Electricity was difficult to understand even for renowned physicists at that time. When Hendrik Anton asked the Parisian translator of the treatise to explain to him the physical meaning of several of Maxwell's equations, he heard that these equations had no physical meaning and should be considered only from the point of view of mathematics.

Studying at Leiden University was easy for Lorentz, and the very next year (1871) he defended his dissertation with honors and became a bachelor of physical and mathematical sciences.

During this time he continued to study Maxwell's works. In addition to studying field equations, the future scientist, twenty years before the discovery of the electron, suggested that tiny electric charge carriers are the main factors influencing the properties of media.

In order to prepare for his doctoral exams in 1872, Hendrik Anton temporarily left the university and returned to Arnhem, where he taught at a local evening school. In 1873, the future scientist returned to Leiden and passed his doctoral exams with excellent marks.

On December 11, 1875, at the age of 22, Lorenz brilliantly defended his dissertation work on the theory of reflection and refraction of light from the point of view of Maxwell's electromagnetism at the University of Leiden and was awarded the degree of Doctor of Science.

In his dissertation, Hendrik Anton studied the properties of light waves arising from Maxwell's electromagnetic theory and tried to justify the change in the speed of light propagation in a medium by the influence of electrified particles of the body. And although in those days some physicists expressed ideas about the existence of such particles, the structure of the atom was not yet known, and few people took assumptions of this kind seriously.

After Lorenz received his doctorate, Utrecht University offered the young scientist a position as a professor of mathematics, but he refused, preferring the position of teacher in a gymnasium. Lorenz's choice was explained by the fact that he hoped for a professorship at Leiden University.

He did not have to wait long, and on January 25, 1878, twenty-five-year-old Hendrik Anton Lorenz, having become a professor at the first department of theoretical physics in the history of all universities, specially established for him, gave his inaugural speech “Molecular Theories in Physics.” Until his retirement in 1913, Lorenz, despite numerous offers from abroad, remained a faithful knight of his aima mater.

In 1878, Hendrik Anton Lorenz published the famous article “On the relationship between the speed of propagation of light and the density and composition of the medium,” in which he derived the relationship between the density of a transparent substance and its refractive index. The same formula was simultaneously proposed by the Danish physicist Ludwig Lorentz, so it was called the Lorentz-Lorentz formula.

Hendrik Anton's work was based on the assumption that a material object contains oscillating electrically charged particles that interact with light waves. It became another argument in favor of the fact that matter consists of atoms and molecules.

In the early 1880s, a Dutch physicist became interested in the kinetic theory of gases, which describes the movement of molecules and the relationship between their temperature and average kinetic energy.

In subsequent years, already a famous scientist, Lorenz returned to his student research. Already in 1892, he formulated the famous theory of electrons. According to Lorentz, electricity arises from the movement of very small negatively and positively charged particles that have a certain mass and obey classical laws. Only later discoveries established that all electrons are negatively charged and obey the laws of quantum physics.

In addition, the scientist concluded that vibrations of tiny charged particles (electrons), which are less inert than other charged particles of matter, generate electromagnetic waves, including light and radio waves, discovered back in 1888 by the brilliant physicist Heinrich Hertz.

Lorentz's theory explained various electrical, magnetic and optical properties of matter, as well as some electromagnetic phenomena, including the Zeeman effect.

In the same year, 1892, the scientist published the fundamental work “Maxwell’s Electromagnetic Theory and Its Application to Moving Bodies.” In this work, he identified the basic postulates of electronic theory and derived an expression for the force with which the electric field acts on a moving charge (Lorentz force).

At this time, the Dutch physicist worked a lot and fruitfully. From his pen came remarkable works on various problems of physics of that time.

Continuing to study the theory of electrons, Lorentz significantly simplified Maxwell's electromagnetic theory.

In 1892, he published a famous paper on the splitting of spectral lines in a magnetic field. A light beam from a hot gas passing through a slit is divided by a spectroscope into its component frequencies. The result is a line spectrum - a sequence of color lines on a black background, the position of each of which corresponds to a certain frequency. Each gas has its own spectrum.

Hendrik Anton Lorenz proposed that the frequencies in the light beam emitted by a gas were determined by the frequencies of the oscillating electrons. In addition, the scientist put forward the idea that the magnetic field affects the movement of electrons, as a result of which the oscillation frequencies change and the spectrum is split into several lines.

In 1896, Lorentz's student (and later collaborator) Peter Zeeman conducted an experiment that confirmed the effect predicted by Lorentz. He placed a sodium flame between the poles of an electromagnet, causing the two brightest lines in sodium's spectrum to expand. In his further experiments, Zeeman used various substances and became convinced of the correctness of Lorentz's assumption that the extended spectral lines are actually groups of individual close components.

The phenomenon of splitting of spectral lines in a magnetic field was called the Zeeman effect. Peter Zeeman also experimentally confirmed Lorentz's assumption about the polarization of the emitted light. The following year, Hendrik Anton Lorenz developed a theory of the Zeeman effect based on the phenomena of electron oscillations. The Zeeman effect was fully explained later, using quantum theory.

Like his brilliant predecessors Michael Faraday and James Clerk Maxwell, Lorenz believed that all space was filled with ether - a special medium in which electromagnetic waves propagate. Although physicists were unable to determine the properties of the ether, they could not prove either its absence or its presence.

But in 1887, Albert Michelson and Edward Morley conducted a famous experiment in which they tried to determine the speed of the Earth relative to the ether using a high-precision interferometer. In this experiment, light rays had to travel a certain distance in the direction of the Earth's movement, and then the same distance in the opposite direction. Theoretically, different measurement results should have been obtained when the beam moved in one and the other direction. However, the experiments did not reveal any difference in the speed of light, which means that the ether did not affect the movement in any way or does not exist.

In 1892, Irish physicist George Fitzgerald showed that the negative results of experiments on the existence of the ether can be explained if the sizes of bodies that move at speed v, are reduced in the direction of their movement by a factor of ( With– speed of light). In the same year, independently of Fitzgerald, Lorenz proposed his own rationale for the issue. The Dutch scientist also suggested that movement through the ether leads to a reduction in the size of any moving body by an amount that explains the same speed of light rays in the experiment of Michelson and Morley. The hypothesis about the reduction in the size of bodies in the direction of their movement is called the “Lorentz-Fitzgerald contraction.”

Subsequently, the problems considered by famous physicists led to the analysis and revision of many classical ideas about time and space and, ultimately, to the development of the theory of relativity and quantum theory.

In 1895, Lorentz’s new fundamental work “An Attempt on the Theory of Electrical and Optical Phenomena in Moving Bodies” was published in Leiden. It became a reference book on electrodynamics for all physicists of those years. Einstein, Heaviside, Poincaré praised and studied it from the first to the last paragraph. In this work, Lorentz gave a complete systematic presentation of his theory of electrons. In addition, Hendrick suggested that the ether does not take part in the movement of electrons, which means it is motionless. Lorentz noticed that we are not talking about the absolute rest of the ether, but about the fact that any real movements of celestial bodies are movements relative to the ether.

The Dutch scientist introduced the concept of local time, implying that time flows differently for moving bodies than for those at rest. Based on his ideas about electrons, Lorentz described various phenomena - from dispersion phenomena to conductivity phenomena. In addition, he considered electromagnetic phenomena in moving media.

In 1899, Lorenz published the article “A Simplified Theory of Electrical and Optical Phenomena in Moving Bodies,” greatly simplifying his 1895 work.

In 1897, the director of the Cavendish Laboratory, J. J. Thomson, discovered the electron, a freely moving particle, whose properties turned out to be similar to what Lorentz theorized in electrons vibrating in atoms.

At the end of the 19th and beginning of the 20th centuries, Lorentz became one of the leading theoretical physicists in the world. Many scientists turned to him when they encountered unexpected difficulties. The Dutch scientist was well aware of the state of affairs in various areas of physics. His works concerned such areas of physics as the theory of electricity and magnetism, optics, kinetics, thermodynamics, mechanics, etc.

Lorentz came close to creating the theory of relativity, but never took the necessary step away from classical physical laws.

The scientist wrote almost all of his brilliant works while working in Leiden. In 1900, he first went abroad with a scientific report to the International Congress of Physicists in Paris.

"In recognition of the outstanding work they have done by their investigations into the effects of magnetism on the phenomenon of radiation," Dutch physicists Hendrik Anton Lorenz and Pieter Zeeman were awarded the Nobel Prize in Physics for 1902.

In his presentation speech on December 10, 1902, Professor Hjalmar Thiel, Chairman of the Royal Swedish Academy of Sciences, said: “The greatest contribution to the further development of the electromagnetic theory of light was made by Professor Lorentz, whose theoretical work on this topic has borne the richest fruits. Moreover, the Academy also remembers the great role that Professor Lorentz played in the above-mentioned discoveries through his masterful development of the theory of electrons, which became the fundamental law in other fields of physics."

On December 11, 1902, Lorentz delivered his famous Nobel lecture “The Theory of Electrons and the Propagation of Light.”

In 1904, the Dutch scientist published his famous article “Electromagnetic phenomena in a system moving at a speed less than the speed of light.” He derived formulas connecting the spatial coordinates and moments of time of the same event in two different inertial reference systems. These expressions are called “Lorentz transformations”. In addition, the Nobel laureate proposed a formula for the dependence of the mass of an electron on its speed. The effects considered by Lorentz took place in the case when the speed of the body was close to the speed of light.

Based on the work of Lorentz and Poincaré, in 1905 Albert Einstein created the special theory of relativity, which looked at the problems of space and time in a new way. Lorentz's formulas, in fact, explained all the kinematic effects of this theory.

Hendrik Anton contributed to many physical discoveries. He was one of the first to support Einstein's theory of relativity and Max Planck's quantum theory.

Among Lorentz's famous works, one should also highlight the creation of the theory of light dispersion, the explanation of the dependence of the electrical conductivity of a substance on its thermal conductivity, and the derivation of a formula relating the permeability of a dielectric to density.

In 1911, the First International Solvay Congress of Physicists “Radiation and Quanta” was held in Brussels, of which Hendrik Anton Lorentz was elected chairman. His modesty and charm, brilliant knowledge of physics and various languages earned him respect from various scientists. Lorenz was a multiple leader of various international conferences. Particularly noteworthy are the famous Solvay congresses, at which new quantum and relativistic physics were formed. The Dutch scientist was one of the organizers and chairman of these famous meetings of physicists around the world.

In 1912 Lorenz retired from Leiden University. The following year he took up the prestigious post of director of the physics department of the Taylor Museum in Haarlem, which was on the same level of rank as the president of the Royal Society of London.

During his lifetime, Hendrik Anton Lorenz was recognized as an elder of physical science, one of the classics of theoretical physics.

In 1919, Lorenz was invited to take part in one of the greatest hydraulic engineering projects in history - flood prevention and control. He was elected head of a committee to study the movement of sea water during and after the drainage of the Zuider Zee (North Sea Bay). His theoretical calculations - the result of eight years of work - were confirmed by practice and have since been constantly used in hydraulics.

During and after the end of the First World War, the Dutch scientist actively advocated the unification of scientists from different countries. Lorenz achieved the opening of free libraries in Leiden and devoted a lot of time to teaching issues.

In 1923, Lorenz became a member of the League of Nations' International Committee for Intellectual Cooperation, and in 1925, its chairman.

At the beginning of 1881, the famous Dutch scientist married Alletta Katherine Kaiser, the niece of Kaiser's astronomy professor. His wife gave birth to four children, but one of them died in infancy. The eldest daughter, Gertrude Luberta Lorenz, followed in her father's footsteps and became a physicist. Thanks to his wife, who took full charge of raising the children, Hendrik Anton could devote himself entirely to his favorite work - science.

In one of the letters of 1927 to his daughter, the scientist wrote that he plans to complete several scientific projects, but what he has already done is also good, because he lived a long and wonderful life.

In addition to the Nobel Prize, the famous scientist was awarded various medals and prizes, among which are the Copley (1918) and Rumford (1908) medals of the Royal Society of London.

Lorenz was a member of various academies of sciences and scientific societies. In 1912, he became secretary of the Netherlands Scientific Society, in 1910 he was elected a foreign corresponding member of the St. Petersburg Academy of Sciences, and in 1925 - a foreign honorary member of the USSR Academy of Sciences. In 1881 Lorenz became a member of the Royal Academy of Sciences in Amsterdam. In addition, Hendrik Anton was an honorary doctor of the Universities of Paris and Cambridge, a member of the Royal and German Physical Societies of London.

On February 4, 1928, at the age of 75, Hendrik Anton Lorenz died in Haarlem. National mourning was declared in the Netherlands.

During his lifetime, Lorentz became a living classic of physics. After his death, one of the lunar craters was named after him.

Citizenship Netherlands Area of scientific interests physics Institution Leiden University Alma mater Leiden University Known for: Lorentz force Awards Nobel Prize in Physics
Copley Medal

Four years later, he published a seminal article, “Electromagnetic phenomena in a system moving at a speed less than the speed of light.” Lorentz derived formulas connecting spatial coordinates and moments of time in two different inertial reference systems (Lorentz Transformations). The scientist managed to obtain a formula for the dependence of electron mass on speed.

Particularly noteworthy is the participation of Hendrik Lorentz in the preparation and holding of the “I International Congress of Solvay Physicists”. It took place this year in Brussels, and was dedicated to the problem of “Radiation and quanta.” 23 physicists took part in its work, Lorentz chaired.

"	We can't help but feel like we're at a dead end; old theories are becoming less and less able to penetrate the darkness that surrounds us on all sides	"
Hendrik Anton Lorenz, from the introduction

He sets the task for physicists to create new mechanics: “We will be happy if we manage to get even a little closer to the future mechanics in question.”

This year, Lorenz resigns from the University of Leiden, but lectures once a week and acts as secretary of the Netherlands Scientific Society. A year later he moved to Harlem, where he worked as director of the physical office of the Teiler Museum. Since then he has been a member of the international commission on intellectual cooperation of the League of Nations, and since then he has headed it.

Lorenz loved his country and wrote.

100 famous scientists Sklyarenko Valentina Markovna

LORENZ HENDRIK ANTON (1853 – 1928)