Xiangyu Li

A musical instrument sounds cleaner when its strings don't touch anything extraneous. Roughly the same principle drives the new optical magnetometer: a glass cuvette the size of a matchbox is filled with rubidium vapor, and its walls are coated with a thin layer of paraffin, like wax on a ski track.

The most abundant construction material on Earth, concrete, hides its deepest secrets at nanometer scales. Its strength and tendency to creep slowly under load are governed by a microscopic gel of calcium silicate hydrate (C-S-H), whose structure is as chaotic as a frozen vortex of atoms.