Quantum mechanics and Einstein's general relativity explain how the Universe works at the tiniest and largest scales, respectively. Quantum mechanics has revealed the probabilistic nature of fundamental particles, while Einstein's general relativity describes how the fabric of spacetime is warped by mass and energy to produce gravity.

An international team of researchers directly measured gravity’s predicted effect on the quantum phase of freely falling atoms.

Physicists observed a quantum state change in ultracold atoms. This change matched Einstein's equivalence principle for a freely falling object. The experiment used a Quantum…