Deep in the Black Hills of South Dakota, USA, in a former gold mine, a tank of liquid xenon has been used to produce an unusual particle reaction that may be a link to “dark matter”. Scientists conducting an experiment there say they have found a single “unexplained particle interaction” that resembles a dark matter particle, although the researchers have not called this a confirmed detection. really observe. This is the closest scientists have come to discovering possibly the most elusive form of matter in the universe. This is what we know. What is dark matter? Dark matter is an invisible substance that is believed to make up about 27 percent of all matter in the universe. Similarly, dark energy, which is believed to make up 68 percent of everything in the universe, is an invisible force that separates galaxies and accelerates the expansion of the universe. Ordinary matter, which is all we can see and touch, represents only 5 percent of everything that exists. Scientists found evidence that this invisible matter exists in the universe by observing its gravitational pull, which affects how galaxies spin and how light bends around large clumps of it. What it’s made of and what it looks like The first clue to the existence of dark matter was discovered in the 1930s, when Swiss astronomer Fritz Zwicky noticed that galaxies in the Coma Cluster were moving too fast for the cluster’s visible mass to hold them in place, suggesting that something else had to be applying gravity. Similar observations were made over the following decades: all signs pointing to the presence of invisible matter, scientists say. On Sunday, NASA, the US space agency, announced that it was launching a $4 billion project, the Nancy Grace Roman Space Telescope, which will investigate both dark matter and energy. An illustration shows NASA’s Nancy Grace Roman Space Telescope in orbit [NASA via Reuters]What have scientists found in the latest experiment? Scientists say they have found a single, unexplained particle interaction that resembles a dark matter particle, although they said this is not the same as directly detecting dark matter itself. The LUX-ZEPLIN (LZ) experiment was led by an international team of 250 scientists and engineers from 38 institutions. At its center is an underground tank at the Sanford Underground Research Facility (SURF), in the state of South Dakota, in the United States, which contains ultrapure liquid xenon, surrounded by hundreds of light sensors. The theory the experiment was testing is this: If a hypothetical dark matter particle called a WIMP (weakly interacting massive particle) reacts with the nucleus of a xenon atom, it would produce two flashes of light at a specific energy level. After days of data collected between March 2023 and April 2024, the LZ team discovered one such event on June 16, 2023. Sam Eriksen, leader of the study and senior research associate at the University of Bristol, presented the findings Tuesday at the TeV 2026 Particle Astrophysics conference in Japan. “We understand our detectors and their background so well,” Eriksen explained in a press release, “that even a single outstanding event, like the one found, is important.” Rick Gaitskell, an LZ spokesman and a physicist at Brown University, said scientists “don’t want to get ahead of ourselves.” “We do not claim to have seen dark matter,” he added. A physicist at the University of Sydney who also worked on the study told ABC News the event is exciting because it has been retested several times and has held up. “This event simply will not go away even after many, many checks.”
