Monday, July 26, 2010

A century after van der Waals Nobel Prize

The director of the UQ Physics Museum, Norm Heckenberg asked me to give a public lecture marking the centennial of the 1910 Nobel Prize in Physics.

Johannes van der Waals received the Prize in 1910 "for his work on the equation of state for gases and liquids". Reading his biography and prize speech (in preparation for the talk on August 17) increased my appreciation for just how significant van der Waals work was, both in itself and in terms of what it led to.

His significant achievements include:

1. realising that the gas and liquid are actually the same phase of matter and could be described by the same equation of state

2. the law of corresponding states

3. the Gibbs free energy is the fundamental quantity needed to understand transitions between different phases of matter

van der Waals contributions were not just significant in that they provided an explanation for existing experimental data on a diversity of gases but they also led to completely new and unexpected scientific insights and discoveries, including:

a. the law of corresponding states led to some of the most important concepts in theoretical physics today: universality, scaling, and the renormalisation group.

b. the law of corresponding states guided Kamerlingh Onnes to the liquification of hydrogen and helium. this led to the discovery of superconductivity and superfluidity.

c. van der Waals theory of binary mixtures highlighted that the Gibbs free energy is the key quantity for understanding phase transitions.

d. the hypothesis of the van der Waals force for non-polar molecules (a residual attractive interaction between neutral spherical and uncharged atoms such as helium and argon) was explained by Fritz London and Eisenschitz in 1930, following the development of quantum theory. Their use of the notion of interactions mediated by virtual transitions turned out to be a foundational idea in quantum field theory where low-energy interactions are determined by high-energy states and processes.

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