The search for dark matter, the invisible substance that makes up 83% of the universe's matter, is undergoing a radical transformation. For decades, scientists focused on WIMPs (Weakly Interacting Massive Particles), which seemed the ideal candidate. However, after years of experiments in the deepest underground laboratories, such as the Apennine massif in Italy, the Jinping Mountains in Sichuan, and the Homestake Mine in South Dakota, liquid xenon detectors have found no trace of WIMPs. Instead, they encountered an unexpected obstacle: neutrinos, lightweight particles produced by the Sun and other stars, create a background noise called the 'neutrino fog'. This fog makes it nearly impossible to distinguish a potential dark matter signal from neutrinos.
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WIMP failure opens the door to new ideas
The lack of positive results has not discouraged physicists but spurred them to explore new avenues. As Kathryn Zurek, a theoretical physicist at Caltech, explains: 'We haven't found WIMPs, nor new particles at the Large Hadron Collider. So naturally, we broadened our scope.' The scientific community is now embracing a variety of approaches: quantum sensors, liquid helium detectors, and even searching for dark matter in Jupiter's atmosphere. Gray Rybka, a physicist at the University of Washington, emphasizes that 'there is great excitement, and finally the technology is ready.'
From supersymmetry to controlled chaos
The WIMP idea originated from supersymmetry, a theory that predicted a heavier 'superpartner' for every known particle. When the LHC found no trace of these particles, the theory lost appeal, but WIMPs survived as independent candidates. Today, with next-generation detectors entering the neutrino fog, the last major WIMP experiment, called XLZD, might be the last of its kind. It would use 60 to 80 metric tons of liquid xenon, nearly the entire annual global production of this rare element, but the US Department of Energy seems to have already abandoned the project by the end of 2025.
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The uncertainty about dark matter's nature is frustrating but also liberating. 'The potential range of candidates is so enormous that the odds of any single experiment finding it are very small,' says Hugh Lippincott, a physicist at UC Santa Barbara. Yet, this uncertainty is generating a flurry of creative proposals, from searching for ultralight axions to using atomic clocks as detectors. The hunt has transformed from a focused search into a free-for-all, where every hypothesis is considered.
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For more on dark matter and new detection technologies, read Dark Matter Hunt and Kenya Solar: Is Europe Watching from the Sidelines?. For authoritative scientific background, see the Wikipedia page on dark matter.
Source: https://www.technologyreview.com/2026/06/18/1138755/search-for-dark-matter-blown-wide-open
