How philosophy helps solve puzzles in chemistry

We often think that the problems that scientists puzzle over are solved by doing more experiments, revising scientific theories or developing more powerful computational methods. While these are essential elements of scientific progress, philosophical analysis is also an important tool.

Hund’s paradox is one such scientific problem that has drawn the attention of philosophers. In 1927, Friedrich Hund showed that the quantum mechanical description of a chiral molecule predicts as its most stable state that of the superposition of its two chiral structures. This contrasts with empirical evidence, as chemists observe molecules to have one or the other chiral structure.

Since then, chemists and quantum chemists have offered various responses to this paradox. For example, some point out the need to take into account the effects of the environment when describing a molecule’s structure. Philosophers have also attempted to offer some insight. Some propose that the paradox is resolved if we adopt a particular interpretation of quantum mechanics (called the Modal Hamiltonian Interpretation). Others make the more general claim that the paradox is a special case of the measurement problem in quantum mechanics (made familiar by Schrodinger’s cat), and that as such Hund’s paradox should be examined through the perspective of existing solutions to the measurement problem.