Gerardus J. Sizoo Gerardus J. Sizoo Gerardus Johannes Sizoo (8 November 1900 – 4 January 1994) was the first professor of physics at the Vrije Universiteit. He is notable for the establishment and development of the applied physics laboratory in 1930 and the establishment of the Faculty of Mathematics and Physics at the Vrije Universiteit. His doctoral research explored the phenomenon of superconductivity at the University of Leiden, following the lead of Heike Kamerlingh Onnes and Wander Johannes de Haas. He completed his PhD in 1926, with a thesis entitled: "Onderzoekingen over den suprageleidenden toestand van metalen," under Wander Johannes de Haas. In
Helium by Dutch physicist Heike Kamerlingh Onnes by cooling the gas to less than one kelvin. He tried to solidify it by further reducing the temperature but failed because helium does not solidify at atmospheric pressure. Onnes' student Willem Hendrik Keesom was eventually able to solidify 1 cm of helium in 1926 by applying additional external pressure. In 1913, Niels Bohr published his "trilogy" on atomic structure that included a reconsideration of the Pickering–Fowler series as central evidence in support of his model of the atom. This series is named for Edward Charles Pickering, who in 1896 published observations of previously