Charles Reynolds Distinguished Lecture Series

One Hundred Years of Superfluidity

It has been 100 years since Heike Kammerlingh-Onnes first liquefied helium four at 4.2 K above absolute zero in his laboratory in Leiden, the Netherlands. Only three years elapsed before the phenomenon of superconductivity was discovered in Kammerlingh-Onnes' laboratory in metallic mercury at about 4 K.  In the 1930s, liquid helium was found to have remarkable flow properties below 2.17 K  by Piotr Kapitsa. In fact, the liquid could pass through the tiniest cracks with no resistance, hence the name superfluidity.  Jack Allen  shortly thereafter showed that under the proper circumstances this superflow could lead to a spectacular jet of helium rising high above the surrounding helium bath. Fritz London  surmised that superfluidity and superconductivity were manifestations of quantum mechanics on a macroscopic scale. It took almost  50 years before superconductivity was explained by Bardeen, Cooper and Schrieffer in 1957. This led to the speculation that the newly available rare isotope, helium three, might also exhibit superfuidity. This phenomenon was discovered at our laboratory at Cornell University in 1972.  Superfluid helium three was the first magnetic superfluid to be observed. Implications and the significance of superfluidity and superconductivity to other branches of science will be discussed briefly, if time permits.