Hendrik Lorentz

Dutch physicist

• Born: July 18, 1853; Arnhem, Netherlands
• Died: February 4, 1928; Haarlem, Netherlands

Dutch physicist Hendrik Lorentz helped discover the existence of electrons within atoms and developed Lorentz contractions and Lorentz transformations. For his work, Lorentz shared the 1902 Nobel Prize in Physics with fellow physicist Pieter Zeeman.

Primary field: Physics

Specialty: Theoretical physics

Early Life

Hendrik Antoon Lorentz was born on July 18, 1853, in Arnhem, the Netherlands. His mother, Geertruida van Ginkel, died when Lorentz was four years old. He was raised by his father, a nursery owner named Gerrit Frederik Lorentz, and stepmother, Luberta Hupkes. Lorentz attended primary and secondary school in Arnhem. He later enrolled at the University of Leiden, from which he earned his bachelor’s degree in 1871. While completing his doctorate, he taught night school in Arnhem.

Lorentz’s 1875 doctoral thesis, Over de theorie der terugkaatsing en breking van het licht (On the Theory of the Reflection and Refraction of Light, 1997), was based on the work of Scottish physicist James Clerk Maxwell. He refined Maxwell’s theory of electromagnetic radiation, which Lorentz believed did not fully address the reflection and refraction of light in an electromagnetic field.

Shortly after completing his doctorate, Lorentz accepted a position as professor of mathematical and theoretical physics at the University of Leiden. He remained with the university until 1912, when he was appointed curator of the scientific collection and director of the laboratory at Teylers Museum in Haarlem, the Netherlands. During this period, he continued to lecture at the University of Leiden as an honorary professor.

In 1878, Lorentz conducted research on the refraction of light waves passing through a translucent body. Lorentz observed the effect on light refraction in bodies of varying density and formulated an equation to describe it. This is known as the Lorentz-Lorenz equation, named for Lorentz and Danish physicist Ludwig Valentine Lorenz, who had discovered the equation independently.

Lorentz married Aletta Catharina Kaiser, the daughter of the director of the National Gallery of Amsterdam, in 1881. They had one son and two daughters. Their eldest daughter, Geertruida de Haas-Lorentz, later became a physicist and coauthored a number of works with her father.

Life’s Work

For much of his career, Lorentz attempted to develop a theory that fully encompassed the related properties of electricity, magnetism, and light. During the late nineteenth century, physicists had not fully explained why light waves are affected by electromagnetic fields. Prior to Lorentz’s work, many scientists believed in a “luminiferous ether” that supposedly explained the motion of light in the universe. It was assumed that this theoretical ether was the medium through which all light travels. Essentially, the luminiferous ether was part of an attempt to apply classical or Newtonian physics to all of the observable elements of the universe. However, Lorentz and many of his contemporaries determined that light does not travel through only one medium, and that it has qualities that can be influenced by a number of outside forces.

There were numerous attempts by physicists to prove the existence of the ether experimentally, all of which failed. One of the more significant of these attempts was the Michelson-Morley experiment. In 1887, American scientists Albert Michelson and Edward Morley sought to prove that matter moves with relative motion within the ether, which is stationary, and they attempted to detect the presence of the theorized “ether wind.” However, the experiment was unsuccessful. Lorentz wrote a paper in 1895 addressing the shortcomings of the Michelson-Morley experiment and explaining his theory of local time, which indicates that different locations have different rates of time measurement.

Lorentz also proposed the theory that a body in motion contracts as its speed approaches the speed of light. The theory, known as Lorentz contraction, maintains that bodies contract in the same direction as the motion in which they travel. Irish physicist George FitzGerald also formulated a theory that moving bodies shrink as they travel. Though the two scientists developed their theories independently, the Lorentz contraction is also known as the Lorentz-FitzGerald contraction.

The Lorentz contraction became an important part of German-born physicist Albert Einstein’s 1905 theory of special relativity. Though Lorentz, French physicist Henri Poincaré, and several others were on the verge of developing the theory of relativity before Einstein, they failed to discover the essential space-time continuum. Had Lorentz included the space-time continuum in his research, his theory of contraction would have been more accurate than it was. He and FitzGerald believed that objects actually physically deform while traveling. Einstein explained that the theoretical warping of the moving object is in fact a result of a difference in the way space and time are measured in two relative systems.

Lorentz went on to develop the Lorentz transformations (also known as the Lorentz-FitzGerald transformations), which he introduced in a 1904 paper. This set of formulas built on Maxwell’s electromagnetic theory and addressed other changing measures, such as mass and time, in addition to length. The Lorentz transformations also greatly influenced Einstein’s theory of relativity, which further includes the concept of local Lorentz invariance. This idea results from the stipulation in thetheory of relativity that all laws of physics remain invariant under Lorentz transformations.

Lorentz was also one of the first physicists to hypothesize that atoms are made up of smaller charged particles. These particles were later discovered to be electrons. Lorentz further postulated that the oscillation of these electrons in a magnetic field was the source of the observable changes in a light wave’s spectrum and wavelength.

Dutch physicist Pieter Zeeman later proved this hypothesis. In his experiments, Zeeman showed that the wavelength of a light wave passing through an electromagnetic field was noticeably affected as the strength of the magnetic field was intensified. The spectral lines created in Zeeman’s experiments represented a direct correlation between electromagnetic fields and the oscillation of the charged electrons of light waves. This discovery became known as the Zeeman effect. For their contributions to the field, Lorentz and Zeeman were awarded the 1902 Nobel Prize in Physics.

In addition to his papers on Lorentz contractions and Lorentz transformations, Lorentz published works related to the theory of electrons, gravitation, and the refraction of light by crystals. Lorentz had a profound impact on the science of hydraulic engineering as well. A major project concerning the reclamation of the Zuider Zee, a shallow inlet of the North Sea in the Netherlands, was launched in 1919. Lorentz was appointed chair of the engineering committee devoted to this project, and the reclamation was ultimately successful.

Lorentz was a member of a number of committees and organizations related to science and international scientific collaboration. In 1911, many scientists met in Brussels, Belgium, at a summit known as the Solvay Conference. Lorentz was appointed chair of the summit, which addressed the conflicts between classical physics and quantum theory. He encouraged the government of the Netherlands to create an official organization dedicated to the advancement of science, which became known as the Organization for Applied Scientific Research (TNO). Lorentz was elected a member of the League of Nations’ highly exclusive International Committee of Intellectual Cooperation in 1923, and he became president of the committee in 1925.

Lorentz died in Haarlem on February 4, 1928.

Impact

Lorentz is considered one of the most significant physicists of his day. His analysis shaped the foundations of modern physical theory, pushing classical theory beyond its limits, and in so doing exposing the foundational problems modern physics would have to resolve. Largely due to the influence of his research on Einstein’s theory of relativity, his work has remained central to the development of the field of theoretical physics. He exerted a profound influence on the emergent international community of scientists through both his scientific work and his efforts to encourage international scientific cooperation and promote the advancement of science both in the Netherlands and elsewhere. Lorentz’s efforts drew some of the prominent physicists of the early twentieth century to Leiden, making it a leading center for theoretical physics. In addition to sharing the Nobel Prize, Lorentz received the Royal Society’s Rumford and Copley medals, was awarded honorary doctorates from a number of major universities, and was elected to such scientific societies as the Dutch Society of Sciences and the Royal Society of London.

Bibliography

Brown, Harvey A. Physical Relativity: Space-Time Structure from a Dynamical Perspective. New York: Oxford UP, 2005. Print. Provides a history of physical relativity that begins with the work of Lorentz and others whose discoveries paved the way for Einstein’s groundbreaking theory.

De Haas-Lorentz, Geertruida, ed. H. A. Lorentz: Impressions of His Life and Work. Amsterdam: North-Holland, 1957. Print. Contains assessments of Lorentz and his work by his daughter as well as photographs of Lorentz and other leading scientists of the time.

Kumar, Manjit. Quantum: Einstein, Bohr, and the Great Debate About the Nature of Reality. New York: Norton, 2011. Print. Discusses Lorentz’s contributions to the development of quantum theory and includes quotes from correspondence between Lorentz and Einstein.