An international team of scientists have carried out laboratory measurements of dark matter with 40 times greater precision than current astronomical observations, despite not detecting the elusive substance directly, according to a study published in Nature.
Despite centuries of study, many fundamental questions about the Universe remain unanswered, including why matter dominated antimatter after the Big Bang and whether the Universe’s expansion will continue indefinitely.
Dark matter, an invisible substance that does not interact with electromagnetic radiation, is central to these questions. Its gravitational influence is essential for the formation of galaxies, stars, and planets, yet its composition remains unknown. Some physicists hypothesize that dark matter may consist of axions—hypothetical particles millions of times lighter than neutrinos.
The recent experiment tested a particularly “exotic” hypothesis, which proposes that dark matter is not evenly distributed but forms gigantic structures known as topological defects. These defects can be visualized as invisible “bubbles” with domain walls. If such walls exist, the Earth passing through them during its orbit in the Milky Way should produce subtle, detectable effects on sensitive instruments.
To investigate this, researchers from the University of Science and Technology of China (USTC) and Professor Szymon Pustelny from Jagiellonian University built a network of ultraprecise quantum sensors functioning as compasses. If the Earth passed through a domain wall, the needles of these compasses would move simultaneously across multiple sensors. The experiment was conducted in laboratories 300 kilometres apart in China, ensuring that any simultaneous readings could not occur by chance.
“During a one-month-long measurement, the sensors did not record the sought-after signal. Hence, it might appear that the experiment ended in failure. On the contrary, the result is considered to be a success as it enabled scientists to check and falsify an important theoretical model,” the Jagiellonian University said in a press release.
Previously, parameters for detecting such interactions were based on astronomical observations, including the Supernova 1987A explosion. It was assumed that, if axions exist, their interactions with matter would be weaker than estimated from stellar cooling processes. The new experiment shows that Earth-based measurements can exceed these constraints, achieving up to 40 times the precision of previous space-based observations. This was made possible through innovative noise-filtering techniques, similar to those used in LIGO gravitational wave detection, and the use of advanced quantum sensors that amplify subtle signals.
The results published in Nature are expected to guide future experiments that may provide insight into the composition of most of the Universe. Scientists plan to construct even more sensitive sensor networks capable of detecting signals from rapid astrophysical events, such as black hole collisions.
Professor Pustelny will also continue dark matter research as part of a Polish-US collaboration funded by the Fulbright STEM Impact Award programme. (PAP)
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