He believed, that a conductor’s electrical resistance would steadily decrease and drop to nil. In 1911 Kamerlingh Onnes managed to measure the electrical conductivity of pure metals at very low temperatures. Onnes reduced the pressure of the liquid helium and thus achieved temperatures near 1.5 K, which were the coldest temperatures achieved on earth at the time. Doing this, Onned was able to lower the temperature to the boiling point of helium, which is about -269☌. About four years after founding the famous laboratory, Onnes managed to liquefy helium through multiple precooling stages and the Hampson-Linde cycle based on the Joule-Thomson effect. The laboratory is now known as Kamerlingh Onnes Laboratory. Onnes founded a very large cryogenics laboratory and invited other researchers to the location, which made him highly regarded in the scientific community. Starting in 1882, Kamerlingh Onnes served as professor of experimental physics at the University of Leiden, where he stayed until 1923. Kammerlingh Onnes obtained his masters in 1878 and a doctorate in 1879 with a thesis on “ Nieuwe bewijzen voor de aswenteling der aarde” ( New proofs of the rotation of the earth). Subsequently he became assistant to Johannes Bosscha, Dutch physicist and director of the TU Delft. In 1871, Kamerlingh Onnes‘ talents for solving scientific problems was already apparent, since he was awarded a Gold Medal for a competition sponsored by the Natural Sciences Faculty of the University of Utrecht, followed the next year by a Silver Medal at the University of Groningen. – Motto of Kamerlingh Onnes’ Laboratory Early Yearsīorn in Groningen, Netherlands, Kamerlingh Onnes also attended the city’s university and studied under the famous Robert Bunsen and Gustav Kirchhoff at the University of Heidelberg in the early 1870s. „Door meten tot weten“ – “Through measurement to knowledge” Kamerlingh Onnes discovered superconductivity. On April 8, 1911, Dutch physicist and Nobel Laureate Heike Kamerlingh Onnes found that at a temperature of only 4.2 K (-269° C) the resistance in a solid mercury wire immersed in liquid helium suddenly vanished.
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