Johannes Diderik van der Waals (Dutch: [joːˈɦɑnəz ˈdidərɪk fɑn dər ˈʋaːls] ; 23 November 1837 – 8 March 1923) was a Dutch theoretical physicist who received the Nobel Prize in Physics in 1910 "for his work on the equation of state for gases and liquids." Van der Waals started his career as a schoolteacher, before becoming the first physics professor of the University of Amsterdam when its status was upgraded to Municipal University in 1877. His name is primarily associated with the van der Waals equation, an equation of state that describes the behavior of gases and their condensation to the liquid phase. His name is also associated with van der Waals forces (forces between stable molecules), with van der Waals molecules (small molecular clusters bound by van der Waals forces), and with the van der Waals radius (size of molecules). James Clerk Maxwell once said that, "there can be no doubt that the name of Van der Waals will soon be among the foremost in molecular science." In his 1873 thesis, Van der Waals noted the non-ideality of real gases and attributed it to the existence of intermolecular interactions. He introduced the first equation of state derived by the assumption of a finite volume occupied by the constituent molecules. Spearheaded by Ernst Mach and Wilhelm Ostwald, a strong philosophical current that denied the existence of molecules arose towards the end of the 19th century. The molecular existence was considered unproven and the molecular hypothesis unnecessary. At the time Van der Waals's thesis was written (1873), the molecular structure of fluids had not been accepted by most physicists, and liquid and vapor were often considered as chemically distinct. But Van der Waals's work affirmed the reality of molecules and allowed an assessment of their size and attractive strength. His new formula revolutionized the study of equations of state. By comparing his equation of state with experimental data, Van der Waals was able to obtain estimates for the actual size of molecules and the strength of their mutual attraction. The effect of Van der Waals's work on molecular physics in the 20th century was direct and fundamental. By introducing parameters characterizing molecular size and attraction in constructing his equation of state, Van der Waals set the tone for modern molecular science. That molecular aspects such as size, shape, attraction, and multipolar interactions should form the basis for mathematical formulations of the thermodynamic and transport properties of fluids is presently considered an axiom. With the help of the Van der Waals's equation of state, the critical-point parameters of gases could be accurately predicted from thermodynamic measurements made at much higher temperatures. Nitrogen, oxygen, hydrogen, and helium subsequently succumbed to liquefaction. Heike Kamerlingh Onnes was significantly influenced by the pioneering work of Van der Waals. In 1908, Onnes became the first to make liquid helium; this led directly to his 1911 discovery of superconductivity.
Biography
Early years and education Johannes Diderik van der Waals was born on 23 November 1837 in Leiden, Netherlands, the eldest of ten children of Jacobus van der Waals, a carpenter, and Elisabeth van den Berg. As was usual for all girls and working-class boys in the 19th century, Van der Waals did not go to the kind of secondary school that would have given him the right to enter university. Instead he went to a school of "advanced primary education", which he finished at the age of fifteen. He then became a teacher's apprentice in an elementary school. Between 1856 and 1861 he followed courses and gained the necessary qualifications to become a primary school teacher and head teacher. In 1862, Van der Waals began to attend lectures in mathematics, physics and astronomy at the university in his city of birth, although he was not qualified to be enrolled as a regular student in part because of his lack of education in classical languages. However, Leiden University had a provision that enabled outside students to take up to four courses a year. In 1863 the Dutch government started a new kind of secondary school (HBS, a school aiming at the children of the higher middle classes). Van der Waals—at that time head of an elementary school—wanted to become a HBS teacher in mathematics and physics and spent two years studying in his spare time for the required examinations. In 1865, Van der Waals was appointed as a physics teacher at the HBS in Deventer and in 1866, he received such a position in The Hague, which was close enough to Leiden to allow Van der Waals to resume his courses at the university there. In September 1865, just before moving to Deventer, Van der Waals married the eighteen-year-old Anna Magdalena Smit.
Professorship Van der Waals still lacked the knowledge of the classical languages that would have given him the right to enter university as a regular student and to take examinations. However, it so happened that the law regulating the university entrance was changed and dispensation from the study of classical languages could be given by the minister of education. Van der Waals was given this dispensation and passed the qualification exams in physics and mathematics for doctoral studies. At Leiden University, on June 14, 1873, van der Waals defended his doctoral thesis Over de Continuïteit van den Gas- en Vloeistoftoestand (on the continuity of the gaseous and liquid state) under Pieter Rijke. In the thesis, he introduced the concepts of molecular volume and molecular attraction. In September 1877, van der Waals was appointed the first professor of physics at the newly founded Municipal University of Amsterdam. Two of his notable colleagues were the physical chemist Jacobus Henricus van 't Hoff and the biologist Hugo de Vries. Until his retirement at the age of 70, Van der Waals remained at the Amsterdam University. He was succeeded by his son Johannes Diderik van der Waals, Jr., who also was a theoretical physicist. In 1910, at the age of 72, Van der Waals was awarded the Nobel Prize in physics. He died at the age of 85 on March 8, 1923.
Scientific work
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