A new experimental proposal suggests detecting a particle of gravity is far easier than anyone imagined. Now physicists are debating what it would really prove.

Detecting a graviton — the hypothetical particle thought to carry the force of gravity — is the ultimate physics experiment. Conventional wisdom, however, says it can’t be done. According to one infamous estimate, an Earth-size apparatus orbiting the sun might pick up one graviton every billion years. To snag one in a decade, another calculation(opens a new tab) has suggested, you’d have to park a Jupiter-size machine next to a neutron star. In short: not going to happen.

A new proposal overturns the conventional wisdom. Blending a modern understanding of ripples in space-time known as gravitational waves with developments in quantum technology, a group of physicists has devised a new way of detecting a graviton — or at least a quantum event closely associated with a graviton. The experiment would still be a herculean undertaking, but it could fit into the space of a modest laboratory and the span of a career.