Lorentz, Hendrik Antoon (physicist)


(1853-1928) Dutch Theoretical Physicist (Classical Electromagnetism, Optics), Relativist

Hendrik Lorentz extended james clerk maxwell’s theory of electromagnetism by proposing that since light is generated by oscillating electric currents, the presence of a strong magnetic field would have an effect on the charged particles that make up the oscillating currents. Specifically, it would result in a splitting of spectral lines by causing the wavelengths of the lines to vary. In 1896, his student pieter zee-man experimentally confirmed Lorentz’s theory, and they shared the Nobel Prize in physics in 1902. Of equal importance, Lorentz developed a set of equations that mathematically predicted the increase of mass, shortening of length, and dilation of time for a physical object in motion with velocities ranging from zero to the speed of light. These equations, which later became known as the Lorentz transformation, played a major role in albert einstein’s development of the theory of special relativity.

Lorentz was born in Arnhem, the Netherlands, on July 18, 1853. His childhood was marked by the death of his mother when he was four and his businessman father’s remarriage five years later. Hendrik was educated at local schools and entered the University of Leiden in 1870; in less than two years he had earned the B.Sc. degree in mathematics and physics. He left Leiden at the age of 19 to return to Arnhem as a night school teacher, while writing his Ph.D. thesis, which refined the electromagnetic theory of James Clerk Maxwell so that it more satisfactorily explained the reflection and refraction of light. He received his degree in 1875 at the age of 22.

When Lorentz was 24, in 1878, he assumed the chair of theoretical physics, newly created for him, at Leiden, where he would remain for the next 39 years. In 1881, he married Aletta Catharina Kaiser. The couple had a son and two daughters, one of whom became a physicist. During that time he published an essay on the relationship between the velocity of light in a medium and the density and composition of the medium. The resulting formula, developed almost simultaneously by the Danish physicist Ludwig Lorenz, has become known as the Lorenz-Lorentz formula.

In the process of attempting to develop a unified theory to explain the relationship of electricity, magnetism, and light, Lorentz proposed that if electromagnetic radiation is produced by the oscillation of electric charges, the source of light might be traced to the oscillation of charges inherent in atoms of matter. If this were the case, a strong magnetic field should have an effect on the oscillations and thus on the wavelength of the light generated. The theory was confirmed in 1896 by the discovery of the Zeeman effect, in which a magnetic field splits spectral lines. This made it possible to apply the molecular theory to the theory of electricity and to explain the behavior of light waves passing through moving transparent bodies.

Lorentz’s electron theory was not successful in explaining the null result of the Michel-son-Morley experiment that attempted to measure the “luminiferous ether,” the hypothetical medium in which light waves were thought to propagate. The experimenters had hoped to measure the ether by observing changes in the speed of light on the basis of interference patterns created when a light beam was split in two and the separated beams were guided along perpendicular paths and then recombined. To their dismay, no changes in the speed of light were observed. In an attempt to salvage the concept of the ether, Lorentz and the Irish physicist francis george fitzgerald, working independently, developed the idea, now known as the Lorentz-FitzGerald contraction hypothesis, that the length of an object moving through the ether contracts in the direction of the motion. When Lorentz heard of FitzGerald’s work, he was glad to have an ally, commenting, “I have been rather laughed at for my idea over here.” Both were scrupulous in acknowledging one another’s work, each believing that the other had published first.

In 1899, Lorentz showed that the Lorentz-FitzGerald contraction resulted from a process delineated in a group of equations, which became known as Lorentz transformations, that mathematically predict the increase of mass, shortening of length, and dilation of time for an object traveling at near the speed of light. Taken together, they compose the revolutionary picture of space and time that Einstein would present in 1905 in his theory of special relativity. Einstein would base his theory on two postulates: (1) the laws of physics take the same form in all inertial frames; (2) in any inertial frame, the velocity of light c is the same whether the light is emitted by a body at rest or by a body in uniform motion. From these he deduced both the Lorentz transformations and the Lorentz-FitzGerald contraction.

However, even though Lorentz was recognized as a major contributor to the mathematics of special relativity, he himself never felt comfortable with Einstein’s conclusions:

[I find] a certain satisfaction in the older interpretation according to which the ether possesses some substantiality, space and time can be sharply separated, and simultaneity without further specification can be spoken of.

His attitude toward the second great physical revolution of the day, quantum mechanics, was similarly conservative. In 1911, he chaired the first Solvay Conference in Brussels, which met to consider the problem of having two different approaches, classical and quantum physics. His private hope was that it would be possible somehow to reincorporate quantum theory into classical physics.

Hendrik Lorentz developed a set of equations, later known as the Lorentz transformation, that played a major role in Albert Einstein's development of the theory of special relativity.

Hendrik Lorentz developed a set of equations, later known as the Lorentz transformation, that played a major role in Albert Einstein’s development of the theory of special relativity.  

From 1912, when he accepted a double position as curator at the Teyler Institute in Haarlem and secretary of the Dutch Society of Sciences, onward, Lorentz continued at Leiden as extraordinary professor, delivering his famous Monday morning lectures for the rest of his life. In 1919, he assumed a leading role in the project to reclaim the Zuyderzee in the Netherlands, a great work of hydraulic engineering. His theoretical calculations played an important role in the project. Enjoying great prestige in Dutch governmental circles, he initiated steps leading to the creation of a society for applied scientific research. In 1923, he was elected to membership in the International Committee of Intellectual Cooperation of the League of Nations and became its chairman in 1925.

He died in Haarlem on February 5, 1928. On the day he was buried the state telegraph and telephone services in Holland were suspended for three hours as a tribute to “the greatest man Holland has produced in our time.” The renowned British physicist ernest rutherford delivered an appreciative graveside oration.

Next post:

Previous post: