| Willem Keesom | |
| Birth Place: | Texel, Netherlands |
| Death Place: | Leiden, Netherlands |
| Field: | physics |
| Doctoral Advisor: | Johannes Diderik van der Waals |
| Known For: | helium |
Willem Hendrik Keesom ([1] [2]) (21 June 1876, Texel - 3 March 1956, Leiden) was a Dutch physicist who, in 1926, invented a method to freeze liquid helium.He also developed the first mathematical description of dipole–dipole interactions in 1921. Thus, dipole–dipole interactions are also known as Keesom interactions.He was previously a student of Heike Kamerlingh Onnes, who had discovered superconductivity (a feat for which Kamerlingh Onnes received the 1913 Nobel Prize in Physics).
He also discovered the lambda point transition specific-heat maximum between Helium-I and Helium-II in 1930.[3]
In 1924 he became member of the Royal Netherlands Academy of Arts and Sciences.[4] In 1966, the minor planet 9686 Keesom was named after him.