Johannes Diderik van der Waals

Johannes Diderik van der Waals was born in Leiden in 1837, the eldest of ten children of a carpenter. His schooling ended at the elementary level and he became a schoolteacher, studying at Leiden University in his spare time without the classical languages then required for a degree. Legislative changes eventually let him qualify, and he took his doctorate in 1873 at the age of thirty-six.

That thesis, 'Over de Continuïteit van den Gas- en Vloeistoftoestand' — on the continuity of the gaseous and liquid states, a title borrowed in tribute from Andrews — is one of the most consequential doctoral dissertations ever written. Maxwell learned Dutch in order to read it, and remarked that van der Waals's name would soon be among the foremost in molecular science. It made two corrections to the ideal gas law: molecules occupy volume, so the available space is V − nb, and they attract one another, reducing the pressure by an amount proportional to n²/V².

The patched equation produced something nobody had derived before: an isotherm with an inflection point, a genuine critical point falling out of theory rather than observation, with T_c = 8a/27Rb. It also yielded, unbidden, the law of corresponding states — rewrite the equation in units of each fluid's own critical point and the parameters vanish, so every fluid becomes the same fluid. That was universality glimpsed a century early, and it had immediate practical force: it told experimentalists where to look, and guided Kamerlingh Onnes to the liquefaction of helium in 1908.

Van der Waals became the first professor of physics at the University of Amsterdam in 1877 and received the Nobel Prize in 1910. His theory is a mean-field theory, and in the modern reckoning it gets the critical exponents wrong — it predicts β = 1/2 where measurement gives 0.326. It remains right about everything else, and the weak intermolecular attraction it identified is universally called the van der Waals force.