Hans Rudolf Ott

Title

100 Years of Liquid Helium

Abstract

The first liquifaction of Helium was achieved in the summer of 1908 at  the University of Leiden in the Netherlands. This breakthrough gave the decisive impetus for the emerging new branch of low-temperature physics, which was first dominated by research on the properties of  liquid Helium itself and, naturally, on the phenomenon of superconductivity of metals. Later, the phenomenon of superfluidity of both 4He and 3He played a major role in the physics of phase transitions and investigations on the possible ground states of condensed matter. The idea of diluting 3He into superfluid 4He and its physical realization provided a new way to reach very low temperatures and greatly simplified the technique of refrigeration into the milli-Kelvin range of temperatures. Liquid Helium served as the indispen sable medium for boosting the research in solid state physics and for that reason also made its way to Zurich more than 50 years ago.