Heike Kamerlingh Onnes liquefied helium, opening access to temperatures far below those reached with other common cryogenic liquids. This enabled electrical measurements through the low-temperature transition of metals and the discovery of superconductivity. His later liquid-helium experiments also investigated persistent currents, connecting the sharp resistance change with sustained electrical behavior in a closed circuit. The progression shows how a new cooling technique can expose phenomena that are inaccessible at higher temperatures.[ref]
The Liquefaction of Helium by Heike Kamerlingh Onnes. 1908 report, helium liquefaction and experimental access
[ref]Further Experiments with Liquid Helium, J (Continued) by Heike Kamerlingh Onnes. liquid-helium experiments on superconducting electrical behavior
A physicist.[ref]
https://actorenregister.nationaalarchief.nl/actor-persoon/kamerlingh-onnes-prof-h-te-leiden. Independent biographical identity and professional specialization
Helium liquefaction supplied a route to very low temperatures. The resistance-versus-temperature experiment for superconductivity and measurements of superconducting persistent current show how reaching those conditions opened new questions about electrical behavior.
Portrait of Heike Kamerlingh Onnes
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Heike Kamerlingh Onnes was a Dutch physicist known for his pioneering work in low-temperature physics. He was born on September 21, 1853, and passed away on February 21, 1926. Onnes is perhaps best known for his discovery of superconductivity in 1911, when he observed that the electrical resistance of mercury disappeared completely when it was cooled below a certain critical temperature (approximately 4.2 K, or -268.95 °C).