Slowed-down light just felt the gravity of something 6 millimetres wide

Gravity is so weak that feeling the pull of a marble-sized object was long considered near-impossible. Researchers at Shanghai Jiao Tong University in China have now done it: their sensor, built around a tiny suspended pendulum and light slowed almost to a stop inside a glass cavity, detected the gravitational tug of a 1.2-gram ball just 6 millimetres across. The peer-reviewed result, in Nature Nanotechnology, is a step toward probing where gravity meets the quantum world.