Gravity, the attraction between objects with mass, is the weakest of the four fundamental forces governing physical processes. Detecting the tiny gravitational pull of objects that are just a few millimeters in size and have a very small mass is extremely challenging.

Reliably measuring the gravitational fields of microscopic objects could open new possibilities for research and the development of new technologies. For instance, it could allow physicists to explore how gravity relates to quantum physics and develop new instruments to study tiny objects.

Researchers at Shanghai Jiao Tong University and other institutions recently developed a new sensor that can detect the gravitational pull of millimeter-sized objects. This sensor, introduced in a paper published in Nature Nanotechnology, is based on a suspended structure called a torsion pendulum and an optical microcavity, a structure that confines light.