Hendrik Antoon Lorentz The Nobel Prize in Physics 1902

biography

Hendrik Antoon Lorentz (July 18, 1853, Arnhem – February 4, 1928, Haarlem) was a Dutch physicist and the winner of the 1902 Nobel Prize in Physics for his work on electromagnetic radiation. Lorentz attended primary school in Arnhem until he was 13 years of age when he entered the new High School there. He entered the University of Leiden in 1870 but, in 1872, he returned to Arnhem to take up teaching evening classes. He worked for his doctorate while holding the teaching post.

In his doctoral thesis for University of Leiden (1875), Lorentz refined the electromagnetic theory of James Clerk Maxwell to better explain the reflection and refraction of light. His name is now associated with the Lorentz-Lorenz formula. He was appointed professor of mathematical physics at the Univiersity of Leiden in 1878. During his time there he was primarily interested in a single theory to explain the relationship of electricity, magnetism, and light. Lorentz theorized that the atoms might consist of charged particles and suggested that the oscillations of these charged particles were the source of light. This was experimentally proven in 1896 by Pieter Zeeman, a pupil of Lorentz.

In 1895 in an attempt to explain the Michelson-Morley experiment, Lorentz introduced the concept of local time (different time rates in different locations). He also proposed that bodies approaching the velocity of light contract in the direction of motion (see FitzGerald-Lorentz Contraction). (George FitzGerald had already arrived at this conclusion.) In 1904 (one year before the publication of Einstein's paper) Lorentz extended this work and developed the Lorentz transformations. These mathematical formulas describe basic effects of the theory of relativity, namely the increase of mass, shortening of length, and time dilation that are characteristic of a moving body. Lorentz was chairman of the first Solvay Conference held in Brussels in the autumn of 1911. This conference looked at the problems of having two approaches, namely the classical physics and quantum theory. However Lorentz never fully accepted quantum theory and hoped it would be incorporated back into the classical approach. In 1912 Lorentz became director of research at the Teyler Institute in Haarlem, although he remained honorary professor at Leiden and gave weekly lectures there. Lorentz received a great many honours for his outstanding work. He was elected a Fellow of the Royal Society in 1905. The Society awarded him their Rumford Medal in 1908 and their Copley Medal in 1918.

Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field. The electric field can be produced by stationary electric charges, and gives rise to the electric force, which causes static electricity and drives the flow of electric current in electrical conductors. The magnetic field can be produced by the motion of electric charges, such as an electric current flowing along a wire, and gives rise to the magnetic force one associates with magnets. The term "electromagnetism" comes from the fact that the electric and magnetic fields are closely intertwined, and, under many circumstances, it is impossible to consider the two separately. For instance, a changing magnetic field gives rise to an electric field; this is the phenomenon of electromagnetic induction, which underlies the operation of electrical generators, induction motors, and transformers. The term electrodynamics is sometimes used to refer to the combination of electromagnetism with mechanics. This subject deals with the effects of the electromagnetic field on the mechanical behavior of electrically charged particles.

The force that the electromagnetic field exerts on electrically charged particles, called the electromagnetic force, is one of the four fundamental forces. The other fundamental forces are the strong nuclear force (which holds atomic nuclei together), the weak nuclear force (which causes certain forms of radioactive decay), and the gravitational force. All other forces are ultimately derived from these fundamental forces. However, it turns out that the electromagnetic force is the one responsible for practically all the phenomena one encounters in daily life, with the exception of gravity. Roughly speaking, all the forces involved in interactions between atoms can be traced to the electromagnetic force acting on the electrically charged protons and electrons inside the atoms. This includes the forces we experience in "pushing" or "pulling" ordinary material objects, which come from the intermolecular forces between the individual molecules in our bodies and those in the objects. It also includes all forms of chemical phenomena, which arise from interactions between electron orbitals. Furthermore, light is actually a kind of travelling disturbance in the electromagnetic field (i.e. electromagnetic waves.) Therefore, all optical phenomena are actually electromagnetic phenomena.

An accurate theory of electromagnetism, known as classical electromagnetism, was developed by various physicists over the course of the 19th century, culminating in the work of James Clerk Maxwell, who unified the preceding developments into a single theory and discovered the electromagnetic nature of light. In classical electromagnetism, the electromagnetic field obeys a set of equations known as Maxwell's equations, and the electromagnetic force is given by the Lorentz force law. One of the peculiarities of classical electromagnetism is that it is difficult to reconcile with classical mechanics, but it is compatible with special relativity. According to Maxwell's equations, the speed of light is a universal constant, dependent only on the electrical permittivity and magnetic permeability of the vacuum. This violates Galilean invariance, a long-standing cornerstone of classical mechanics. One way to reconcile the two theories is to assume the existence of a luminiferous aether through which the light propagates. However, subsequent experiments efforts failed to detect the presence of the aether. In 1905, Albert Einstein solved the problem with the introduction of special relativity, which replaces classical kinematics with a new theory of kinematics that is compatible with classical electromagnetism. In this theory, magnetism turns out to be the effect that relativity has on simple electrostatics and does not need a special set of equations (like Maxwell's equations in a classical Universe).

Remarkably, in another paper published in that same year, Einstein undermined the very foundations of classical electromagnetism. His theory of the photoelectric effect posited that light could exist in discrete particle-like quantities, which later came to be known as photons. Einstein's theory of the photoelectric effect extended the insights that appeared in the solution of the ultraviolet catastrophe presented by Max Planck in 1900. In his work, Planck showed that hot objects emit electromagnetic radiation in discrete packets, which leads to a finite total energy emitted as black body radiation. Both of these results were in direct contradiction with the classical view of light as a continuous wave. Planck's and Einstein's theories were progenitors of quantum mechanics, which, when formulated in 1925, necessitated the invention of a quantum theory of electromagnetism. This theory, completed in the 1940s, is known as quantum electrodynamics (or "QED"), and is one of the most accurate theories known to physics.

Hendrik Antoon Lorentz was born at Arnhem, The Netherlands, on July 18, 1853, as the son of nursery-owner Gerrit Frederik Lorentz and his wife n?e Geertruida van Ginkel. When he was four years old, his mother died, and in 1862 his father married Luberta Hupkes. In those days the grade school did not only have school hours in the morning and in the afternoon, but also in the evening, when teaching was more free (in a sense resembling the Dalton method). In this way, when in 1866 the first highschool (H.B.S.) at Arnhem was opened, Hendrik Lorentz, as a gifted pupil, was ready to be placed in the 3rd form. After the 5th form and a year of study of the classics, he entered the University of Leyden in 1870, obtained his B.Sc. degree in mathematics and physics in 1871, and returned to Arnhem in 1872 to become a night-school teacher, at the same time preparing for his doctoral thesis on the reflection and refraction of light. In 1875, at the early age of 22, he obtained his doctor's degree, and only three years later he was appointed to the Chair of Theoretical Physics at Leyden, newly created for him. In spite of many invitations to chairs abroad, he always remained faithful to his Alma Mater. From 1912 onward, when he accepted a double function at Haarlem as Curator of Teyler's Physical Cabinet and Secretary of the "Hollandsche Maatschappij der Wetenschappen" (Dutch Society of Sciences), he continued at Leyden as Extraordinary Professor, delivering his famous Monday morning lectures for the rest of his life. The far-seeing directors of Teyler's Foundation thus enabled his unique mind to be freed from routine academic obligations, permitting him to spread his wings still further in the highest secluded realms of science, which are attainable by so few. From the start of his scientific work, Lorentz took it as his task to extend James Clerk Maxwell's theory of electricity and of light. Already in his doctor's thesis, he treated the reflection and refraction phenomena of light from this standpoint which was then quite new. His fundamental work in the fields of optics and electricity has revolutionized contemporary conceptions of the nature of matter.

In 1878, he published an essay on the relation between the velocity of light in a medium and the density and composition thereof. The resulting formula, proposed almost simultaneously by the Danish physicist Lorenz, has become known as the Lorenz-Lorentz formula. Lorentz also made fundamental contributions to the study of the phenomena of moving bodies. In an extensive treatise on the aberration of light and the problems arising in connection with it, he followed A.J. Fresnel's hypothesis of the existence of an immovable ether, which freely penetrates all bodies. This assumption formed the basis of a general theory of the electrical and optical phenomena of moving bodies.

From Lorentz stems the conception of the electron; his view that his minute, electrically charged particle plays a r?le during electromagnetic phenomena in ponderable matter made it possible to apply the molecular theory to the theory of electricity, and to explain the behaviour of light waves passing through moving, transparent bodies. The so-called Lorentz transformation (1904) was based on the fact that electromagnetic forces between charges are subject to slight alterations due to their motion, resulting in a minute contraction in the size of moving bodies. It not only adequately explains the apparent absence of the relative motion of the Earth with respect to the ether, as indicated by the experiments of Michelson and Morley, but also paved the way for Einstein's special theory of relativity.

It may well be said that Lorentz was regarded by all theoretical physicists as the world's leading spirit, who completed what was left unfinished by his predecessors and prepared the ground for the fruitful reception of the new ideas based on the quantum theory.

In 1919, he was appointed Chairman of the Committee whose task it was to study the movements of sea water which could be expected during and after the reclamation of the Zuyderzee in The Netherlands, one of the greatest works of all times in hydraulic engineering. His theoretical calculations, the result of eight years of pioneering work, have been confirmed in actual practice in the most striking manner, and have ever since been of permanent value to the science of hydraulics. An overwhelming number of honours and distinctions from all over the world were bestowed on Lorentz. International gatherings were presided over by him with exceptional skill, both on account of his amiable and judicious personality and his masterly command of languages. Until his death he was Chairman of all Solvay Congresses, and in 1923 he was elected to the membership of the "International Committee of Intellectual Cooperation" of the League of Nations. Of this Committee, consisting of only seven of the world's most eminent scholars, he became the President in 1925.

Through his great prestige in governmental circles in his own country, Lorentz was able to convince them of the importance of science for national production. He thus initiated the steps which finally led to the creation of the organisation now generally known under the initials T.N.O. (Dutch for Applied Scientific Research). Lorentz was a man of immense personal charm. The very picture of unselfishness, full of genuine interest in whoever had the privilege of crossing his path, he endeared himself both to the leaders of his age and to the ordinary citizen.

In I88I Lorentz married Aletta Catharina Kaiser, whose father, J.W. Kaiser, Professor at the Academy of Fine Arts, was the Director of the Museum which later became the well-known Rijksmuseum (National Gallery) of Amsterdam, and the designer of the first postage stamps of The Netherlands. There were two daughters and one son from this marriage. The eldest daughter Dr. Geertruida Luberta Lorentz is a physicist in her own right and married Professor W.J. de Haas, Director of the Cryogenic Laboratory (Kamerlingh Onnes Laboratory) of the University of Leyden.

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