History of the ITFA

For the 50th anniversary of the ITFA in 1999, A.J. Kox held a speech on the 10th of December about the history of the institute.

One hundred and twenty-five years of theoretical physics in Amsterdam

A.J. Kox

For some of you, the title of my talk this afternoon may be a bit confusing: aren’t we celebrating the 50th anniversary of the Institute of Theoretical Physics? Why then this strange title: 125 years of theoretical physics? I am going to confuse you even more: in spite of my title, I will in fact speak about 60 years of theoretical physics, the first sixty-odd years between 1877 and the outbreak of the Second World War in 1940. The reason is that as a historian of science I am reluctant to say much about events as recent as 50 years ago. It is simply too early to make a balanced judgment about the impact postwar Dutch theoretical physics has made and the place it will take in history. (Other people, for instance those assembled today in Stockholm, seem to have had less qualms in this respect...) That may be a disappointment for some of you, who came here in the hope of hearing interesting or gossipy stories about people they have known (or perhaps even about themselves). To soften the disappointment a bit, I have collected some facts about the creation of the institute in the booklet that each of you has received at the entrance.

The old school in the Roetersstraat

The old school building in the Roetersstraat, the housing of the ITF until 1963

So 60 years it will be. Let me first explain the year 1877. In that year the University of Amsterdam was created. Before that time, as many of you know, Amsterdam had not been without an institution of higher learning altogether: there was the venerable Athenaeum Illustre, dating from 1632, but this school was limited in scope and could only offer lower degrees. With the establishment of the university, made possible by a new law of higher education, a science faculty was created, which of course included a chair of physics. The first physics professor was 40-year old Johannes Diderik van der Waals. Van der Waals was an interesting person. He came from a simple background (his father was carpenter) and had worked his way up by first becoming a teacher and then completing his university studies in Leyden. There he obtained his doctorate in 1877 with a dissertation on the continuity of the gaseous and liquid states, in which he derived his famous equation of state. The dissertation gave him instant fame and inspired the famous Scottish physicist James Clerk Maxwell to study what he called the “low-Dutch language.” That Van der Waals was appointed in Amsterdam was thus no big surprise.

Van der Waals was not an easy person to deal with: he kept his distance from most others and inspired in his students a mixture of awe and admiration. He could be very firm with them, even harsh, as we know from recollections of several of his students.

Let me leave Amsterdam for a moment and make a brief excursion to another university town: Leyden. The reason is that in the same year, 1877, in Leyden also a new very young professor of physics was appointed. His name was Hendrik Antoon Lorentz and we all know him now as one of the greatest Dutch physicists of the past centuries. In this context it is ironic, by the way, that Lorentz was not first choice for the Leyden chair. Van der Waals was, but he preferred Amsterdam over Leyden. Why do I mention Lorentz’s appointment? For the important reason that Lorentz’s chair was officially a chair of theoretical physics. It was the first such chair in the Netherlands and one of the first of its kind in Europe.

Van der Waals and Heike Kamerlingh Onnes, 1908

Van der Waals (rechts) and Heike Kamerlingh Onnes in Leiden with the helium 'liquefactor' (1908)

Back to Amsterdam. Van der Waals was officially professor of physics, not theoretical physics, and he also became director of the physics laboratory. In spite of this we can say that the tradition of theoretical physics in the Netherlands started in 1877 with the appointment of Van der Waals and Lorentz: Van der Waals left the supervision of experimental work as much as possible to assistants and later to a second professor and concentrated on his own theoretical work in gas theory and thermodynamics. He accomplished much in this field and many of his contributions are of lasting value. Back in 1973, when the centenary of his doctorate was celebrated at a conference in Amsterdam, one of the main invited papers had the significant title “Van der Waals in his time and the present revival.”

When we look at the accomplishments of Amsterdam physics in general, it soon becomes clear that during the first decades Van der Waals dominated the scene with his theoretical work. In retrospect four main achievements can be distinguished: the equation of state (which, strictly speaking, was derived before the Amsterdam days, but it was further worked out in Amsterdam), the law of corresponding states (1880), the theory of binary mixtures (1891) and finally the theory of capillary phenomena (1893). All of these theories made a lasting impact on theoretical physics.

Let me elaborate a bit on the theory of binary mixtures: one of the unexpected predictions of this theory is that under certain circumstances a mixture of two components will demix, that is, that it will separate into its two components. This and other predictions were subject of experimental research as recent as 25 years ago and it turned out that Van der Waals had made the right predictions.

Van der Waals was a theoretical physicist par excellence: he combined mathematical talent with a sharp instinct for physical phenomena. Physics always took first place: some of his derivations are mathematically questionable but thanks to his physical insight they lead to useful physical results nevertheless. For him and his fellow theoretical physicists mathematics was a tool to be used, not to be pursued as a goal in itself.

Group picture, 1951

Roetersstraat 1a (1951). From left to right: R. van Wageningen, R. Bird, J. van Kranendonk, J. de Boer, E.G.D. Cohen

In this respect theoretical physics departed from a longer-existing nineteenth-century tradition, namely mathematical physics, in which mathematics plays a more central role. Interestingly, one of Van der Waals’s close colleagues, the mathematician Johannes Diederik Korteweg, can be characterized as a typical mathematical physicist. Korteweg, who was Van der Waals’s first student (and in fact the first to obtain a doctorate at the University of Amsterdam) was much interested in applications of mathematics. We know him nowadays in the first place as one of the names in the famous Korteweg-De Vries equation, but he has done much more. He collaborated with Van der Waals on thermodynamical subjects, in particular on the shape of the so-called free energy surface. It is typical that he took this work as a starting point for some pure mathematical work on the classification of the various types of such surfaces. Van der Waals would never have done such a thing.

Let me, although it is a bit outside the topic of my talk, say a few words about experimental physics. After all, Van der Waals was director of the physics laboratory. Recent research by Ad Maas has brought to light that during the first decades little of any importance was accomplished. This stands in contrast with experimental physics in Leiden, where in the physics laboratory, under the directorship of Kamerlingh Onnes, important research was done in the field of magneto-optics and low temperature physics. But Amsterdam was stil not without influence in Dutch experimental physics: much of the low-temperature work relied heavily on the theoretical work of Van der Waals. So, in an indirect way, Amsterdam did play a role in Dutch experimental physics.

The Valckenierstraat 65

Construction site at the Valckenierstraat

The experimental situation changed when Pieter Zeeman entered the scene in Amsterdam, around the turn of the century. Zeeman was a brilliant experimentalist with a well-defined research program in the field of magneto-optics. Interestingly, like his Leiden counterpart, he too relied on theoretical support from outside, in this case from Lorentz in Leiden. Zeeman took over the directorship of the laboratory in 1908, when Van der Waals retired. Two years later, in 1910, Van der Waals was awarded the Nobel Prize in physics.

In 1908 it also became clear that theoretical physics would become a family affair in Amsterdam: upon his retirement Van der Waals’s chair was split in one for theoretical physics and one for applied thermodynamics. The new professor of theoretical physics was Van der Waals’s son, Johannes Diderik van der Waals jr. The younger Van der Waals was, like his father, not an easy person to deal with. He was distant, sometimes sarcastic. The following anecdote is perhaps characteristic for his personalty: Van der Waals jr. used to avoid speaking about the “Van der Waals equation,” but instead referred to it as (and now I have to switch to Dutch for a moment) “De wet van Pa” (“Dad’s law”). At some point he was administering an oral examination and he asked the student: “Kent u de wet van Pa?” (“Do you know Dad’s law?”) The student thought for a moment and replied: “Nee, professor, maar wel de wet van Ohm.” (“No professor, but I do know Ohm’s law.”) Unfortunately, the joke is untranslatable: it hinges on the fact that the Dutch word “oom,” which is pronounced just like “Ohm,” means “uncle.” Van der Waals was so totally not amused that he failed the student instantly.

Portrait of J. de Boer, 1981

Jan de Boer at the time of his retirement in 1981

In a way, being his father’s successor must have been difficult for Van der Waals jr. Although he was an excellent physicist, he was not of the Nobel prize winning class of his father. He did work in the fields of radiation theory and brownian motion. Especially in the latter subject he achieved important results. Still, as the years went on, Van der Waals gradually lost interest in physics. He became an editor of the prestigious Dutch literary journal De Gids, and wrote about the foundations of physics and other philosophical topics. Especially the exciting new developments in physics, such as quantum mechanics, had little interest to him. That theoretical physics in Amsterdam suffered because of this goes without saying. In the thirties, ambitious and eager young students, such as Jan de Boer, were dependent on assistants, visiting lecturers or, curiously, the astronomer Anton Pannekoek, to become acquainted with the “new” physics.

the institute in 1976

The institute in 1976

That brings me to the beginning of World War Two and to the end of what we can call the “era Van der Waals” in Amsterdam. Van der Waals retired in 1941 and was, because of the war circumstances, only succeeded in 1946, when Jan de Boer was appointed and with this appointment theoretical physics in Amsterdam made a fresh start. As I have said before, it is still too early to make a sound historical assessment of the achievements of the post-war years. But there is one achievement the importance of which is beyond any doubt: the creation by Jan de Boer of the Institute for Theoretical Physics at the University of Amsterdam, fifty years ago. In the booklet you have all received you can read that this was not an easy job. But it was a major achievement that had an enormous impact on theoretical physics in Amsterdam. Let me therefore finish by expressing my gratitude and my admiration to Jan de Boer for his vision and his persistence.