Heike Kamerlingh Onnes
1853-1926
Dutch Experimental Physicist
Heike Kamerlingh Onnes is best known for his life-long investigations into the properties of matter at very low temperatures. The very first experimental physicist to liquefy helium in 1908, Kamerlingh Onnes went a step further in the field of cryogenics when, in 1911, he discovered what is called today superconductivity.
Born in Groningen, The Netherlands, in 1853, Kamerlingh Onnes entered the city's university at age 17. After receiving his "candidaats" degree (approx. B.Sc.) in 1871, he went to Heidelberg, Germany, as a student of Robert Wilhelm Bunsen (1811-1899) and Gustav Robert Kirchhoff (1824-1887) from October 1871 to April 1873. He then returned to Groningen to complete his studies, where he passed his "doctoraal" examination (approx. M.Sc.) in 1878; a year later he was awarded the doctorate magna cum laude. Kamerlingh Onnes's academic career began when he was appointed assistant at Delft Polytechnic School, a position he held until 1882 when, at the young age of 29, he became the new professor of physics at Leiden University. He would stay in Leiden for the next 42 years.
The first thing Kamerlingh Onnes did, as new professor of physics in Leiden, was to reorganize the physical laboratory in such a way that it would suit his own program of experimental physics. This he asserted right from the start in the motto taken from his inaugural address: "Door meten tot weten," or "Knowledge through measurement." Based on the solid ground of theory developed by two eminent Dutch contemporaries—Johannes Diderik van der Waals (1837-1923) and Hendrik Antoon Lorentz (1853-1928)—Kamerlingh Onnes undertook his low-temperature studies while simultaneously establishing one of the first cryogenic laboratories in the world. Years of effort culminated in the liquefaction of helium in 1908 (something that happens at the very low temperature of 4.2Kelvin or -451.84°F). Leiden's laboratory, at the time, was justly nicknamed "the coldest spot on Earth." From then until his retirement in 1923, Kamerlingh Onnes would remain the undisputed monarch of low-temperature physics.
Just three years later, in 1911, while doing experiments with extremely cold mercury, he discovered an entirely new phenomenon, which he called supraconductivity (later superconductivity). Maintained at very low temperatures, some materials become superconductors, which means that, as Kamerlingh Onnes discovered, they display virtually no resistance to electric currents. Even though the experiment was easily reproduced afterwards, it took 46 years before three American physicists explained theoretically the underlying mechanism for superconductivity. Yet another very important phenomenon tied to very low temperature physics was the discovery of superfluidity. A superfluid is a liquid that, when cooled to no more than a few degrees above absolute zero (-459.4°F), lacks all inner friction.
When, in 1913, Kamerlingh Onnes received the Nobel Prize for physics "for his investigations on the properties of matter at low temperatures which led, inter alia, to the production of liquid helium," he opened up new vistas of experimental and theoretical researches. In fact, besides his own, seven other Nobel prizes (totaling 14 people) were awarded for work on low-temperature physics, the latest being in 1998. Superconductors are now widely used in hospitals in the form of magnetic resonance imaging (MRI) machines, and in the fields of high-energy physics and nuclear fusion. Furthermore, materials with superconductivity properties are investigated so that some day they can be used in levitating trains.
Kamerlingh Onnes is one of the most prominent scientists the Netherlands has ever produced. In Leiden today, the town's old university physics laboratory (also called the Kamerlingh Onnes Laboratory) is a tourist site, as is the Boerhaave Museum, which displays the thermos flask in which liquid helium was collected for the first time and the helium liquefier that made Kamerlingh Onnes's original experiment possible.
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