Scientists deep underground in the United States may have caught a fleeting glimpse of dark matter, the mysterious invisible substance thought to make up more than 85 percent of the universe.
Researchers from the University of Bristol, participating in an international collaboration of 250 scientists across 39 institutions, observed a rare collision between a single atom and an unknown particle. The event was recorded by LUX-ZEPLIN (LZ), one of the world's most sensitive particle detectors, located nearly a mile underground at the Sanford Underground Research Facility in South Dakota.
Physicists believe the collision might have been caused by a Weakly Interacting Massive Particle, or WIMP—a candidate particle long hypothesized to compose dark matter. Because dark matter reflects no light and interacts weakly with normal matter, it has never been directly detected despite accounting for most of the mass in the cosmos.
Lead researcher Dr. Sam Eriksen described the signal as an incredibly exciting potential first step in understanding dark matter, though scientists emphasize that further analysis is needed. The team cautioned that a single event is not definitive proof. The observation carried a statistical significance rating of 2.6 sigma, whereas the scientific standard for confirming a discovery requires a 5-sigma threshold.
The preliminary findings were revealed at a scientific conference in Japan and have yet to undergo peer review. While researchers continue to rule out background noise and known particle interactions, they hope that future data from the detector will reveal additional candidate events.