This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Rice University researchers have used a magnetically levitated particle to search for ultraheavy dark matter, extending the hunt for some of the heaviest possible forms of the invisible matter thought to hold galaxies together. Led by Christopher Tunnell, associate professor of physics and astronomy, the researchers used a tiny floating magnet as a highly sensitive detector designed to register the faint push an ultraheavy dark matter particle could produce as it passed through.
Dark matter plays a fundamental role in the structure of the universe, influencing the formation and stability of galaxies such as the Milky Way. However, scientists have yet to determine its composition. Understanding what dark matter is made of could enhance knowledge of how galaxies formed and evolved.
Most dark matter experiments focus on particles with masses similar to those of atoms, but some theories propose that the particles might be significantly heavier, potentially reaching the mass of a living cell. This Rice-led research demonstrates how a floating magnet can broaden the search to include these heavier candidates. The findings were released at the 2026 International Conference on Particle Physics and Cosmology.
"Dark matter could be hiding at masses that our traditional experiments were never built to reach," Tunnell said. "By turning a tiny floating magnet into a detector, we can begin searching a part of the dark matter landscape that has largely been out of experimental reach despite being the focus of extensive theoretical study by my Rice cosmology colleague Andrew Long." The detector is a permanent magnet roughly the size of a grain of sand. It levitates above a superconductor cooled to just above absolute zero, the lowest temperature physically attainable.
Because the magnet does not touch any surface, friction is significantly reduced, allowing even a minute force to set it in motion. The researchers monitored the magnet closely enough to detect movement about one-hundredth the width of an atom. This sensitivity enabled them to search for extraordinarily weak forces.
If an ultraheavy dark matter particle were to pass through the detector and interact with ordinary matter, it could give the magnet a tiny push. "Instead of looking for a steady signal, we are waiting for very small knocks," said Juehang Qin, a Rice postdoctoral researcher and corresponding author of the study. "The challenge is making the detector quiet and sensitive enough that if something unusual pushes it, we can see that motion and determine whether it could be dark matter." The researchers gathered about a month of data and concentrated their analysis on quiet overnight periods, when external disturbances were minimized.
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