When I explain topology to students, I start with a knot in a rope. You can stretch it, twist it or shake it, but the knot stays until you cut the rope. Physicists have found that some materials and devices carry similar “knots” in how waves move through them. These are topological properties, labeled by whole numbers that don’t change under small imperfections. That robustness is why topology has become one of the central ideas in modern physics. It promises electronics, photonics and quantum devices that tolerate defects and noise.

In recent experiments involving hydrogels and water droplets, researchers have proposed that exposure to visible light could make water evaporate faster without heating it. However, direct evidence that light acts on water itself has proven elusive.

Physicists with the University of Illinois Urbana-Champaign’s Grainger College of Engineering have identified a new form of superconducting behavior. Experiments on the metal uranium ditelluride reveal that Cooper pairs, the composite electron units responsible for superconductivity, can organize into nonuniform patterns that exist even when the main superconducting phase is absent.