One of the most profound open questions in modern physics is: “Is gravity quantum?” The other fundamental forces—electromagnetic, weak, and strong—have all been successfully described, but no complete and consistent quantum theory of gravity yet exists.

“Theoretical physicists have proposed many possible scenarios, from gravity being inherently classical to fully quantum, but the debate remains unresolved because we’ve never had a clear way to test gravity’s quantum nature in the lab,” says Dongchel Shin, a Ph.D. candidate in the MIT Department of Mechanical Engineering (MechE).

“The key to answering this lies in preparing mechanical systems that are massive enough to feel gravity, yet quiet enough—quantum enough—to reveal how gravity interacts with them.”