Scientists Report Possible Evidence of Dark Matter Particle in South Dakota

Dark matter is an invisible substance that is believed to bind the universe; scientists in South Dakota may have found new signs of it. Deep beneath the Black Hills of South Dakota, in an old gold mine, a tank of liquid xenon has been used to produce an unusual particle reaction that may be linked to dark matter. Scientists conducting an experiment there report that they have found a single unexplained particle interaction resembling a dark matter particle, though researchers have not confirmed this as a detection. Dark matter and dark energy are substances whose presence has been detected, but have yet to be observed directly. This is the closest scientists have come to potentially uncovering the universe’s most elusive form of matter. Dark matter is believed to make up roughly 27 percent of all matter in the universe. Dark energy, thought to account for 68 percent of everything in the universe, is an invisible force that pushes galaxies apart and accelerates the expansion of the universe. Ordinary matter, which includes everything visible, constitutes only 5 percent of all existence. Scientists have inferred the existence of this unseen matter by observing its gravitational effects on galaxies and light. The first clue to dark matter's existence was identified in the 1930s by Swiss astronomer Fritz Zwicky, who noted that galaxies in the Coma Cluster moved too quickly for the visible mass to hold them, indicating the presence of additional gravitational forces. NASA announced on Sunday the launch of a $4 billion project, the Nancy Grace Roman Space Telescope, aimed at investigating dark matter and dark energy. The LUX-ZEPLIN (LZ) experiment, conducted by an international team of 250 scientists and engineers from 38 institutions, is centered at the Sanford Underground Research Facility (SURF) in South Dakota, where ultra-pure liquid xenon is housed, surrounded by hundreds of light sensors. The experiment tests the theory that a hypothetical dark matter particle called a WIMP (weakly interacting massive particle) could react with a xenon atom's nucleus, producing two flashes of light at a specific energy level. After analyzing 220 days of data collected from March 2023 to April 2024, the LZ team identified one such event on June 16, 2023. Sam Eriksen, the study's lead and a senior research associate at the University of Bristol, presented the findings on Tuesday at the 2026 TeV Particle Astrophysics conference in Japan. Eriksen stated, "We understand our detectors and the backgrounds so well that even a single outstanding event, like the one we found, is important." Rick Gaitskell, the LZ spokesperson and a physicist at Brown University, emphasized that scientists are not claiming to have seen dark matter. Physicists consider this the most compelling signal produced by LZ to date, potentially indicating the first real evidence of a particle that current physics cannot explain. Theresa Fruth, a physicist at the University of Sydney who also contributed to the study, remarked that the event is noteworthy as it has been re-tested multiple times and has consistently shown results. "This event just won’t go away even after many, many checks," Fruth said.