Physicists have finally watched positronium, a short‑lived atom made of an electron and its antimatter twin, behave like a rippling quantum wave instead of a tiny billiard ball. In a set of ...

A strange form of matter called a time crystal has fascinated physicists for about a decade. These systems move in repeating cycles, even without a steady external push.

A cluster of 7,000 sodium atoms has just been coaxed into behaving as a single, ghostly wave, stretching quantum weirdness into a realm that starts to look uncomfortably like everyday matter. Instead ...