Pieter Zeeman was born on May
25, 1865, at Zonnemaire, a small village in the isle of Schouwen,
Zeeland, The Netherlands, as the son of the local clergyman
Catharinus Forandinus Zeeman and his wife, née
Wilhelmina Worst. After having finished his secondary school
education at Zierikzee, the main town of the island, he went to
Delft for two years to receive tuition in the classical
languages, an adequate knowledge of which was required at that
time for entrance to the university. Taking up his abode at the
house of Dr. J.W. Lely, conrector of the Gymnasium and brother of
Dr. C. Lely (Minister of Public Works and known for initiating
and developing the work for reclamation of the Zuyderzee), Zeeman
came into an environment which was beneficial for the development
of his scientific talents. It was here also that he came into
contact with Kamerlingh Onnes (Nobel
Prize in Physics for 1913), who was twelve years his senior.
Zeeman's wide reading, which included a proper mastery of works
such as Maxwell's Heat, and his passion for performing
experiments amazed Kamerlingh Onnes in no small degree, and
formed the basis for a fruitful friendship between the two
scientists.
Zeeman entered Leyden University in 1885 and became mainly a
pupil of Kamerlingh Onnes (mechanics) and Lorentz (experimental
physics): the latter was later to share the Nobel Prize with him.
An early reward came in 1890 when he was appointed assistant to
Lorentz, enabling him to participate in an extensive research
programme which included the study of the Kerr effect - an
important foundation for his future great work. He obtained his
doctor's degree in 1893, after which he left for F. Kohlrausch's
institute at Strasbourg, where for one semester he carried out
work under E. Cohn. He returned to Leyden in 1894 and became
"privaat-docent" (extra-mural lecturer) from 1895 to 1897.
In 1897, the year following his great discovery of the magnetic
splitting of spectral lines, he was called to a lectureship at
the University of
Amsterdam; in 1900 came his appointment as Extraordinary
Professor. In 1908 Van der Waals
(Nobel Prize in Physics for 1910) reached the retiring age of
70 and Zeeman was chosen as his successor, at the same time
functioning as Director of the Physics Laboratory. In 1923 a new
laboratory, specially erected for him, was put at his disposal, a
prominent feature being a concrete block weighing a quarter of a
million kilograms, erected free from the floor, as a suitable
platform for vibration-free experiments. The institute is now
known as the Zeeman Laboratory of Amsterdam University. Many
world-famous scientists have visited Zeeman there or worked with
him for some time. He remained in this dual function for 35 years
- on numerous occasions refusing an invitation to occupy a Chair
abroad - until in 1935 he had to resign on account of his
pensionable age. An accomplished teacher and of kind disposition
he was much loved by his pupils. One of these was C.J. Bakker,
who was from 1955 until his untimely death in an aircraft
accident in 1960 the General Director of the Organisation Européenne pour la Recherche Nucléaire (CERN) at Geneva. Another worker
in his laboratory was S. Goudsmit, who in 1925 with G.E.
Uhlenbeck originated the concept of electron spin.
Zeeman's talent for natural science first became apparent in
1883, when, while still attending the secondary school, he gave
an apt description and drawing of an aurora borealis - then
clearly to be observed in his country - which was published in
Nature. (The Editor praised the meticulous observations of
«Professor Zeeman in his observatory at
Zonnemaire»!)
Zeeman's main theme of investigation has always concerned optical
phenomena. His first treatise Mesures relatives du
phénomène de Kerr, written in 1892, was rewarded
with a Gold Medal from the Dutch Society of Sciences at Haarlem;
his doctor's thesis dealt with the same subject. In Strasbourg he
studied the propagation and absorption of electrical waves in
fluids. His principal work, however, was the study of the
influence of magnetism on the nature of light radiation, started
by him in the summer of 1896, which formed a logical continuation
of his investigation into the Kerr effect. The discovery of the
so-called Zeeman effect, for which he has been awarded the Nobel
Prize, was communicated to the Royal Academy of Sciences in
Amsterdam - through H. Kamerlingh Onnes (1896) and J.D. van der
Waals (1897) - in the form of papers entitled Over den Invloed
eener Magnetisatie op den Aard van het door een Stof uitgezonden
Licht (On the influence of a magnetization on the nature of
light emitted by a substance) and Over Doubletten en
Tripletten in het Spectrum teweeggebracht door Uitwendige
Magnetische Krachten (On doublets and triplets in the
spectrum caused by external magnetic forces) I, II and III. (The
English translations of these papers appeared in The
Philosophical Magazine; of the first paper a French version
appeared in Archives Néerlandaises des Sciences Exactes
et Naturelles, and in a short form in German in
Verhandlungen der Physikalischen Gesellschaft zu
Berlin.)
The importance of the discovery can at once be judged by the fact
that at one stroke the phenomenon not only confirmed Lorentz'
theoretical conclusions with regard to the state of polarization
of the light emitted by flames, but also demonstrated the
negative nature of the oscillating particles, as well as the
unexpectedly high ratio of their charge and mass (e/m).
Thus, when in the following year the discovery of the existence
of free electrons in the form of cathode rays was established by
J.J. Thomson, the identity of
electrons and the oscillating light particles could be
established from the negative nature and the e/m ratio of
the particles. The growing number of observations made by other
investigators on studying the effects of using various substances
as light emitters - not all of them explicable by Lorentz'
original theory (the so-called «anomalous Zeeman
effect» could only adequately be explained at a later date,
with the advent of Bohr's atomic theory, quantum wave mechanics,
and the concept of the electron spin) - was assembled by him in
his book Researches in Magneto-Optics (London 1913, German
translation in 1914). Not only has the Zeeman effect thrown much
light on the mechanism of light radiation and on the nature of
matter and electricity, but its immense importance lies in the
fact that even to this day it offers the ultimate means for
revealing the intimate structure of the atom and the nature and
behaviour of its components. It still serves as the final test in
any new theory of the atom.
Already in his second communication Zeeman expressed the opinion
that the accepted existence of strong magnetic fields on the
surface of the sun could be verified, since these should alter
spectral lines derived from the celestial body. (It is typical of
Zeeman to extend physical concepts into the realm of celestial
phenomena.) In a letter to him (1908) the astronomer G.E. Hale,
Director of Mount Wilson Observatory, corroborated this opinion
by means of photographs which indicated that in solar vortices
the spectral lines indeed appeared to be affected by magnetic
fields. Even the theoretical prediction concerning the probable
interrelationship between the directions of polarization and
those of the magnetic fields was subsequently confirmed by
Hale.
With regard to Zeeman's activities outside the field of the
magnetic splitting of spectral lines, mention should first be
made of his work on the Doppler effect in optics and in canal
rays (laboratory tests). A second field of study was that on the
propagation of light in moving media (justification of the
existence of the Lorentz-term in the Fresnel drag coefficient).
Other investigations were those into the influence of the
magnetic moment of the nucleus on the hyperfine structure of
spectral lines. He also succeeded, with J. de Gier, in
discovering a number of new isotopes (38Ar,
64Ni, amongst others) by means of Thomson's parabola
mass spectrograph. Zeeman's predilection for testing fundamental
laws also found expression in his verification - carried out with
an accuracy of < 1: 107 - of the equality of heavy
and inert masses.
Zeeman was Honorary Doctor of the Universities of Göttingen, Oxford, Philadelphia, Strasbourg,
Liège,
Ghent, Glasgow, Brussels and Paris. He was also a member or honorary
member of numerous learned academies, including the very rare
distinction of Associé Etranger of the Académie des
Sciences of Paris. He was also member and Chairman of the
Commission Internationale des Poids et Mesures, Paris. Appointed
member of the Royal Academy of Sciences of Amsterdam in 1898, he
served as the Secretary of the Mathematical-Physical Section from
1912 to 1920. Among the other distinctions may be mentioned the
Rumford Medal of the Royal Society of London, the Prix Wilde of
the Academie des Sciences of Paris, the Baumgartner-Preis of the
Akademie der Wissenschaften of Vienna, the Matteucci Medal of the
Italian Society of Sciences, the Franklin Medal of the Franklin Institute of
Philadelphia, the Henry Draper Medal of the National Academy of
Sciences of Washington. He was also made a Knight of the
Order of Orange-Nassau and Commander of the Order of the
Netherlands Lion.
Outside his field of study Zeeman showed much interest in
literature and the stage. An entertaining host, he loved to
invite his collaborators and pupils to dine with him at his home,
an event preceded by a learned talk in his study and followed by
a gathering in the family circle.
Zeeman married Johanna Elisabeth Lebret in 1895; they had one son
and three daughters. During the last year of his professorship he
suffered from ill-health. He died after a short illness on
October 9, 1943.
From Nobel Lectures, Physics 1901-1921, Elsevier Publishing Company, Amsterdam, 1967
This autobiography/biography was written at the time of the award and first published in the book series Les Prix Nobel. It was later edited and republished in Nobel Lectures. To cite this document, always state the source as shown above.
Copyright © The Nobel Foundation 1902
Pieter Zeeman
