Heike Kamerlingh Onnes (Dutch: [ˈɦɛikə ˈkaːmərlɪŋ ˈɔnəs]; 21 September 1853 – 21 February 1926) was a Dutch experimental physicist who became the first to liquefy helium, cooling it to near 1.5 kelvin (K). For this work, he was awarded the Nobel Prize in Physics in 1913. In 1911, using liquid helium to investigate the electrical conductivity of solid mercury, Kamerlingh Onnes found that its electrical resistance vanishes at 4.2 K, i.e. superconductivity.
Biography Heike Kamerlingh Onnes was born on 21 September 1853 in Groningen, Netherlands, the son of Harm Kamerlingh Onnes, a brickworks owner, and Anna Gerdina Coers of Arnhem. In 1870, Kamerlingh Onnes attended the University of Groningen, where he earned his B.Sc. the following year. From 1871 to 1873, he studied under Robert Bunsen and Gustav Kirchhoff at the University of Heidelberg. He then returned to Groningen, obtaining an M.Sc. in 1878. The following year, he received his Ph.D. with a thesis on Earth's rotation. In 1878, Kamerlingh Onnes became an assistant to Johannes Bosscha, the Director of the Delft Polytechnic, for whom he substituted as a lecturer in 1881 and 1882. In 1882, he was appointed Professor of Experimental Physics and Meteorology at Leiden University. In 1904, he founded a large cryogenics laboratory, and invited other researchers to the location, which made him highly regarded in the scientific community. The laboratory is now known as the Kamerlingh Onnes Laboratory. Kamerlingh Onnes died on 21 February 1926 in Leiden at the age of 72.
Research
Liquefaction of helium
On 10 July 1908, Kamerlingh Onnes was the first to liquefy helium, using several pre-cooling stages and the Hampson–Linde cycle based on the Joule–Thomson effect. This way he lowered the temperature to the boiling point of helium (−269 °C, 4.2 K). By reducing the pressure of the liquid helium, he achieved a temperature near 1.5 K; this was the lowest temperature recorded on Earth at the time. The equipment employed is at the Museum Boerhaave in Leiden. Kamerlingh Onnes received widespread recognition for this work, including the 1913 Nobel Prize in Physics "for his investigations on the properties of matter at low temperatures which led, inter alia, to the production of liquid helium." For further research on low-temperature, Kamerlingh Onnes needed large amounts of helium. This he obtained in 1911 from Welsbach's company, which processed thorianite to produce thorium for gas mantles. Helium is produced as a side product. Previously, he obtained helium from processing monazite, and used the processed monazite (which still contained thorium) to trade for the helium. On Earth, helium is usually found in coexistence with radioactive material, since it is a product of radioactive decay.
Discovery of superconductivity In 1911, Kamerlingh Onnes measured the electrical conductivity of pure metals (mercury, and later tin and lead) at very low temperatures. Some scientists, such as Lord Kelvin, believed that electrons flowing through a conductor would come to a complete halt or, in other words, metal resistivity would become infinitely large at absolute zero. Others, including Kamerlingh Onnes, felt that a conductor's electrical resistance would steadily decrease and drop to nil. Augustus Matthiessen said that when the temperature decreases, the metal conductivity usually improves or in other words, the electrical resistivity usually decreases with a decrease of temperature. On 8 April 1911, Kamerlingh Onnes found that at 4.2 K the resistance in a solid mercury wire immersed in liquid helium suddenly vanished. He immediately realized the significance of the discovery (as became clear when his notebook was deciphered a century later). He reported that "Mercury has passed into a new state, which on account of its extraordinary electrical properties may be called the superconductive state." He published more articles about the phenomenon, initially referring to it as "supraconductivity," and later adopting the modern-day term "superconductivity." On the same day, he noted that "Just before the lowest temperature [about 1.8 K] was reached, the boiling suddenly stopped and was replaced by evaporation in which liquid visibly shrank" which was the first observation of superfluidity of the surrounding helium bath.
Family In 1887, Kamerlingh Onnes married Maria Adriana Wilhelmina Elisabeth Bijleveld, with whom he had one child, named Albert. His brother, Menso Kamerlingh Onnes (1860–1925), was a painter and the father of another painter, Harm Kamerlingh Onnes. Their sister, Jenny, married Floris Verster (1861–1927), also a painter.
Recognition
Memberships
Awards
Commemoration Some of the instruments Kamerlingh Onnes devised for his experiments can be seen at the Boerhaave Museum in Leiden. The apparatus he used to first liquefy helium is on display in the lobby of the physics department at Leiden University, where the low-temperature lab is also named in his honor. His student and successor as director of the lab Willem Hendrik Keesom was the first person who was able to solidify helium, in 1926. The former Kamerlingh Onnes laboratory building is currently the Law Faculty at Leiden University and is known as "Kamerlingh Onnes Gebouw" (Kamerlingh Onnes Building), often shortened to "KOG". The current science faculty has a "Kamerlingh Onnes Laboratorium" named after him, as well as a plaque and several machines used by Kamerling Onnes in the main hall of the physics department. The Kamerlingh Onnes Award (1948) and the Kamerlingh Onnes Prize (2000) were established in his honor, recognizing further advances in low-temperature science. The Onnes effect referring to the creeping of superfluid helium is named in his honor. Kamerlingh Onnes crater on the Moon is named after him. Kamerlingh Onnes is credited with coining the term enthalpy. Kamerlingh Onnes' discovery of superconductivity was named an IEEE Milestone in 2011.
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