Over the past few years, physicists specializing in the arcane behavior of quantum particles have turned their mathematical machinery toward black holes, which, at a distance, resemble particles. Several groups have recently made a surprising finding. They have shown that the behavior of a gravitational (or electromagnetic) wave can be fully known through the actions of just one of its countless particles, as if we could learn the precise silhouette of a tsunami after examining a single water molecule.

Quanta Magazine