Precisely how the disordered solid flows remains unclear. Theorists Lode Pollet and Matthias Troyer of the Swiss Federal Institute of Technology in Zurich presented simulations confirming that atoms can glide along the boundaries between grains without resistance. But some experimenters argue that flow along grain boundaries cannot account for the streaming of 20% of the atoms.

The bigger question may be, will researchers continue to pursue the phenomenon? “Clearly, this is a real effect,” says Sébastien Balibar, an experimenter at the École Normale Supérieure in Paris. “This is really very new physics, even if it isn’t the spectacular idea originally proposed.” But the messy details of defects may not generate as much excitement as the prospect of an oh-so-cool flowing crystal.

From this news report in Science. Here is one of my earlier posts on this issue.