Go back to article: Museums theme – Quest for Absolute Zero: A Human Story about Rivalry and Cold

Liquid helium

The temporary exhibitions at Rijksmuseum Boerhaave are also set to undergo a transformation. This development brings us back to Quest for Absolute Zero, the first major temporary exhibition established according to the new principles that on all fronts represents a break with the past. As already indicated, the background to the exhibition was ‘one hundred years of liquid helium’. Thanks to the loving care of August Crommelin, the cryogenic laboratory of Kamerlingh Onnes is well represented in the Rijksmuseum Boerhaave collection, and with a director who himself obtained his doctoral degree from the University of Leiden in 2005 on the basis of a scientific biography of Kamerlingh Onnes, the temptation to dedicate an exhibition to ‘10 July 1908’ proved irresistible.

But what kind of exhibition should it be? What story should the exhibition tell? To whom and how? What was the target group? How should the exhibition relate to the ‘cold objects’ already present in the permanent exhibition? What roles should fundamental research, the related technology and the people who undertook the work in practice play? What opportunities were available for collaboration with others, and how broad should the exhibition be?

To start with, the story of the liquefaction of helium, as recorded in the biography (Delft, 2007). The story goes as follows: On 10 July 1908, Heike Kamerlingh Onnes was the first to master helium. In room E of his Physical Laboratory, in the very heart of Leiden, after a long and exhausting day, he succeeded in liquefying the last of the ‘permanent’ gases. He thereby achieved a temperature just a few degrees above absolute zero (-273 °C) and Leiden became the coldest place on Earth.

The attack on helium was a carefully planned mega operation. Early in the morning, even before the birds were up, Kamerlingh Onnes had been driven to his laboratory by coach and horses from Huize ter Wetering, his country estate on the Galgewater. There, he immediately donned his white jacket and joined his technicians who had already been hard at work for hours producing liquid hydrogen that together with liquid air was to be used as the precooling agent for the helium. While the Burckhardt pumps squeaked and ground in room A, Kamerlingh Onnes and his workers conscientiously twiddled taps, disconnected gas bottles and anxiously monitored manometers and thermometers. There was no time to snatch even a single bite to eat. By one thirty in the afternoon, twenty litres of liquid hydrogen had been drained into thermos bottles (known as Dewar flasks), sufficient to begin the attack on helium.

At 4:20pm (Onnes’ wife Betsy had by this time anxiously popped by to check on progress, and to feed scraps of bread to her husband as he slogged away) the pump was switched on to allow the helium to circulate. The approach was to first compress the helium to 100 atmospheres, and subsequently to allow it to expand via a porous plug into a vacuum, thermally insulated by a complete ring of thermos flasks containing liquid air and liquid hydrogen. In this way, with every turn around the apparatus, the helium cooled slightly further and the eventual hope was that the fall in temperature would continue to the point at which the helium would condense.

Initially the experiment looked set to fail. One thermometer had already given up the ghost and the second almost refused to fall at all. To Onnes’ relief, however, the cooling process did begin, and at around 6:30pm the temperature was below that of liquid hydrogen. With fluctuating progress, the readout fell to just 6 degrees above absolute zero. By this time, although Kamerlingh Onnes had connected the final bottle from the store of liquid hydrogen to the apparatus, little more had been seen than the occasional swirl.

Suddenly, at -269 °C, four degrees above absolute zero, the thermometer started to indicate a remarkably stable value. This took place around 7:30pm. A colleague, who out of curiosity had come in to check on progress, suggested that there was already liquid present. Illumination by a further lamp indeed indicated that the thermometer was suspended in liquid helium. Contact wires could clearly be seen penetrating the surface of the liquid. ‘Once we actually saw the surface,’ Kamerlingh Onnes wrote in his report for the Academy of Sciences, ‘we never let it out of our sight. It remained clearly visible against the glass wall.’

The experiment had resulted in sixty millilitres of liquid helium, just about a teacup full. After undertaking a number of initial experiments with his new liquid – an attempt to actually freeze it by establishing a vacuum failed – Kamerlingh Onnes decided at 9:40pm that enough was enough. ‘Not only had the equipment been tested to its absolute limit in this experiment and in its preparation,’ he wrote in his Academy report, ‘the maximum possible had also been demanded of my assistants.’

The liquefaction of helium is a highpoint in Dutch (and international) physics. At the same time, it represented the culmination of a programme launched by Kamerlingh Onnes upon his appointment in Leiden in 1882, which he had implemented with a firm hand, a talent for organisation and tremendous perseverance. In his inaugural speech (in which he first coined the phrase ‘Through measurement to knowledge’), Kamerlingh Onnes had announced his wish of testing through experimentation the validity of the molecular theories of his colleague and friend Johannes Diderik van der Waals. The construction of a cryogenic laboratory, a cold factory of never before seen proportions, was the unavoidable consequence of that decision because ‘simple’ substances such as the biatomic O2 and H2, as well as noble gases like helium (discovered on Earth by William Ramsay in 1895) could only be condensed into liquid at extremely low temperatures.

Kamerlingh Onnes’ approach was based on two foundations: accuracy and cold. The first was necessary because the laws of van der Waals only applied by approximation, as a consequence of which the deviations from those laws were needed if physics was to be advanced. That process itself calls for precision measurements, something very close to the heart of Heike Kamerlingh Onnes. During the first period of Kamerlingh Onnes’ professorship, the establishment of a cryogenic laboratory demanded all his energy. Step by step he expanded his empire until it became a bustling cryogenic institution of global proportions; a laboratory offering unique opportunities for research. From all corners of the globe, guest researchers (and visitors) travelled to Leiden (see Figure 5). Kamerlingh Onnes did his level best to make his foreign guests feel welcome, regularly accommodating the more celebrated among them in his villa, Huize ter Wetering. His efforts enabled him to achieve his ideal, namely establishing an international reputation for Dutch physics.

Figure 5

Black and white photograph of a cryogenic laboratory in 1894

The cryogenic laboratory of Kamerlingh Onnes, 1900

Kamerlingh Onnes invested all his energy in his laboratory and in the unique apprentice system for instrument makers (‘the blue boys’) that together formed an ‘organic unit’. Beyond his work, the only thing that mattered to him was his family. Huize ter Wetering was the meeting point for an artistic family, a place that exuded a cosmopolitan atmosphere partly thanks to the presence of innumerable foreign scholars who stayed there (Niels Bohr, Albert Einstein, Madame Curie, William Ramsay) and such visiting artists as Jan Toorop and Albert Verwey.

Heike Kamerlingh Onnes drove his people on like the wind drives the clouds. The true miracle is that a beanpole of a man who as a child spent a year ill at home reading Plutarch, and was forced every summer throughout his life to travel to the Alps as a treatment for his chronic bronchitis, nonetheless found the breath and the energy to establish and even to carry though to fruition an enterprise on the scale of a cryogenic laboratory. Assisted by his wife Betsy, Heike succeeded in focusing his limited strength on one goal: his cold laboratory. Following the success of liquid helium, he discovered superconductivity in 1911 and in 1913 won the Nobel Prize for Physics (for his helium work; the Nobel Committee never even mentioned superconductivity). At the end of his career, in 1924, he managed to bring in a donation of 100,000 guilders from the International Education Board of the Rockefeller Foundation, for the further expansion of his laboratory.

Component DOI: http://dx.doi.org/10.15180/170812/003