Background
Willem Hendrik Keesom was born on June 21, 1876, in Texel, Netherlands. He was the son of H. W. Keesom, a farmer, and N. Dijt.
University of Amsterdam, Amsterdam, Netherlands
Keesom studied physics at the University of Amsterdam, where J. D. van der Waals was one of his teachers. An excellent student, he received the doctorate with a thesis on the isotherms of oxygen and carbon dioxide mixtures in 1904.
1924
Prinsessegracht 4, 2514 AN Den Haag, Netherlands
Keesom was elected a member of the Royal Netherlands Academy in 1924.
1926
Keesom at work in 1926.
1933
Keesom c. 1933.
University of Amsterdam, Amsterdam, Netherlands
Keesom studied physics at the University of Amsterdam, where J. D. van der Waals was one of his teachers. An excellent student, he received the doctorate with a thesis on the isotherms of oxygen and carbon dioxide mixtures in 1904.
German Academy of Sciences Leopoldina, Halle, Germany
Keesom was a member of the German Academy of Sciences Leopoldina and the Pontifical Academy of Sciences.
Pontifical Academy of Sciences, Vatican City, Rome, Italy
Keesom was a member of the Pontifical Academy of Sciences.
Willem Hendrik Keesom was born on June 21, 1876, in Texel, Netherlands. He was the son of H. W. Keesom, a farmer, and N. Dijt.
Keesom studied physics at the University of Amsterdam, where J. D. van der Waals was one of his teachers. An excellent student, he received the doctorate with a thesis on the isotherms of oxygen and carbon dioxide mixtures in 1904.
Keesom became a close collaborator of Kamerlingh Onnes at the University of Leiden, assisting him, for instance, in the liquefaction of helium (1908) and in the writing of a comprehensive treatise on the equation of state for the Enzyklopädie der mathematischen Wissenschaften (1912).
In 1917 Keesom became a teacher, and the next year a professor, of physics at the veterinary school in Utrecht (later incorporated into the university). In 1923 he returned to Leiden to occupy one of the two chairs of experimental physics, the other being occupied by W. J. de Haas in 1924. In 1942 Keesom wrote a standard work on helium, and in 1945 he retired.
At Utrecht, Keesom succeeded in finding a connection between the X-ray diffraction pattern and the intermolecular distance in liquids. This is a good example of his tendency to combine theoretical and experimental methods in order to clarify the picture of liquids and compressed gases without mathematical sophistications.
As a director of the Kamerlingh Onnes laboratory at Leiden, Keesom continued the tradition of low-temperature research, especially (although by no means exclusively) on helium. He was the first to solidify it, by applying external pressure to overcome “repulsion” between the atoms, which in all other crystals is overcome by mutual attraction. Since the saturated vapor pressure is much lower than the pressure needed for crystallization, there is no triple point and the liquid state extends down to absolute zero.
In the course of further work in 1927-1933 it gradually became clear that at very low temperatures the liquid differed fundamentally in its behavior from ordinary liquids and from high-temperature liquid helium. The essence is that below a certain temperature both the liquid and the crystal become so fixed in the ground state that entropy is practically zero, and no further changes occur in it. Such a “thermally degenerate” system no longer behaves as an irreversible thermal system but as a reversible mechanical system.
Keesom was elected a member of the Royal Netherlands Academy in 1924. He was also a member of the German Academy of Sciences Leopoldina and the Pontifical Academy of Sciences.