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Scientists may have taken a major step toward solving one of the biggest mysteries in modern physics: the nature of dark matter.
Deep beneath South Dakota’s Black Hills in the United States, researchers using a giant tank filled with ultra-pure liquid xenon have detected an unusual particle interaction that cannot yet be explained by known sources of background radiation.
The signal could be consistent with a dark matter particle, possibly a hypothetical weakly interacting massive particle (WIMP). However, scientists stress that they have not yet confirmed the discovery of dark matter.
What is dark matter?
Dark matter is an invisible substance believed to make up about 85% of all matter in the universe. Scientists have never directly detected a dark matter particle, but they infer its existence from its gravitational effects on galaxies and other cosmic structures.
Unlike ordinary matter, dark matter does not emit, absorb or reflect light, making it extremely difficult to detect directly.
Ordinary matter—the material that makes up stars, planets, humans and everything we can directly observe—accounts for only about 15% of the universe’s matter. Dark energy is a separate and still poorly understood component associated with the accelerated expansion of the universe.
The first major evidence for dark matter dates back to the 1930s, when Swiss astronomer Fritz Zwicky observed that galaxies in the Coma Cluster were moving too rapidly to be held together by their visible mass alone. He proposed that an unseen form of matter must be providing additional gravitational pull.
Subsequent observations, including studies of galaxy rotation and gravitational lensing, provided further evidence for the existence of dark matter.
What did scientists find?
The latest result comes from the LUX-ZEPLIN, or LZ, experiment, an international collaboration involving about 250 scientists and engineers from 39 institutions.
The detector is located nearly a mile underground at the Sanford Underground Research Facility in South Dakota, inside a former gold mine. It uses about 10 tonnes of ultra-pure liquid xenon and hundreds of sensitive light detectors to search for extremely rare particle interactions.
The LZ team analysed 220 days of data collected between March 2023 and April 2024. During that period, on June 16, 2023, the detector recorded a single unusual event involving a high-energy nuclear recoil.
Researchers say the event has characteristics that could be consistent with an interaction involving a WIMP, one of the leading candidates for dark matter.
The result was presented by University of Bristol researcher Sam Eriksen at the 2026 TeV Particle Astrophysics conference in Japan on September 1.
Why is the finding important?
The event is particularly interesting because researchers have been unable to satisfactorily explain it using known background processes.
The LZ collaboration reports a global statistical significance of 2.6 sigma. That is intriguing but well below the 5-sigma level generally required in particle physics to claim a discovery. Researchers therefore remain cautious and say more data are needed.
The event also appears in a region where the expected background is very low, making it one of the most compelling potential dark matter signals seen by the LZ experiment so far.
If future observations identify additional events with similar characteristics, scientists could gain much stronger evidence that they are seeing dark matter rather than an unusual background process.
What are WIMPs?
WIMPs, or weakly interacting massive particles, are hypothetical particles that have long been considered one of the leading candidates for dark matter.
The theory suggests that a WIMP passing through the LZ detector could occasionally collide with a xenon nucleus. Such a collision would produce a tiny amount of energy that could be detected as flashes of light.
The latest event is compatible with this possibility, but researchers have not established that a WIMP caused it.
So, have scientists discovered dark matter?
Not yet.
The LZ result is an important clue, but it is not definitive evidence. Scientists need more observations and independent confirmation before they can say that a dark matter particle has been detected.
The experiment is continuing to collect data. If more events matching the characteristics of the latest signal are detected, the evidence could become considerably stronger.
For now, the scientific community is treating the finding as a promising lead rather than a confirmed discovery.
Why does dark matter matter?
Understanding dark matter could transform scientists’ understanding of how the universe formed and evolved.
Dark matter is believed to have played a major role in the formation of galaxies and large-scale cosmic structures. Identifying the particles that make up dark matter would therefore answer one of the most fundamental unanswered questions in physics.
The search is continuing through underground detectors such as LZ, particle physics experiments and astronomical observations around the world.
