A post-conference conversation about the interplay between theory and experiment launched a friendship and then a collaboration between two physicists in 1999.

The work of theorist Alexander Balatsky, based at Los Alamos National Laboratory in New Mexico, and experimentalist Séamus Davis, of Cornell University in New York, has focused on high-temperature superconductors — in which the lattice structure influences electron behaviour.

At the time the pair met, many in the field believed most irregularities reported in these lattices to be a “nuisance or a distraction”, says Balatsky. Initially, he took the same view, but, he adds, “while working with Séamus, I changed my mind”.

Since then, he and Davis have found evidence that these irregularities are more extensive at the nanoscale than was previously thought. Balatsky used a mathematical model to estimate where such irregularities might be, and Davis developed imaging techniques to find them.

Their most recent work (see page 546) investigates the influence of 'holes' in the lattice on the formation of electron 'pairs', which are essential to superconductivity.

Their conversation, in search of how and why this happens, will continue.