Have scientists found a particle linked to dark matter?

Deep beneath South Dakota’s Black Hills, scientists have recorded a particle interaction that may offer the closest clue yet to dark matter, the invisible substance believed to bind the universe.

The signal came from a tank of liquid xenon at the Sanford Underground Research Facility, where the LUX-ZEPLIN experiment searches for evidence of dark matter. Researchers say they found one “unexplained particle interaction” resembling a dark matter particle. They stress, however, that the result does not amount to a direct detection or a confirmed discovery.

LUX-ZEPLIN involves 250 scientists and engineers from 38 institutions. Its underground location and liquid-xenon detector are designed to isolate extremely faint interactions that could reveal particles otherwise impossible to observe.

Scientists believe dark matter makes up about 27 percent of all matter in the universe. Dark energy, another unseen component, is thought to account for 68 percent, while ordinary matter, including everything humans can see and touch, represents only 5 percent. Researchers have inferred dark matter’s existence from its gravitational influence on galaxy rotation and the way light bends around massive clusters.

Its nature has remained a mystery because dark matter does not reflect light or electromagnetic radiation. The first major clue emerged in the 1930s, when Swiss astronomer Fritz Zwicky observed that galaxies in the Coma Cluster were moving too quickly for its visible mass to hold them together. Later observations produced similar evidence.

The search is also extending into space. NASA announced the launch of the $4 billion Nancy Grace Roman Space Telescope, which will investigate both dark matter and dark energy. For now, the South Dakota result remains a tantalizing signal rather than the discovery scientists have been seeking.