Scientists may have caught their first glimpse of dark matter – the mysterious substance thought to hold the universe together.
Researchers have detected a single unusual particle interaction deep underground that they have struggled to explain.
They spotted what appears to be a collision between an ordinary atom and a particle unknown to science.
If true, it could help solve one of science’s greatest mysteries – revealing what much of the universe is made of.
The idea of dark matter has been proposed for almost a century, but despite decades of searching, scientists have never directly detected it.
It is thought to make up around 85 per cent of all the matter in the universe, yet it does not appear to absorb, reflect or emit light, making it effectively invisible.
Now, an international team of 250 scientists and engineers from 39 institutions in six countries has spotted something that could provide a clue.
The researchers spent two years scrutinising data from the LUX-ZEPLIN (LZ) experiment, one of the world’s most sensitive dark matter detectors.
Scientists may have caught their first glimpse of dark matter – the mysterious substance thought to hold the universe together (artist’s impression)
Hidden beneath around a mile of rock in South Dakota, the enormous detector contains 10 tonnes of ultra-pure liquid xenon.
The idea is to catch the incredibly faint flashes of light produced when a dark matter particle collides with a xenon atom.
The rock above helps shield the experiment from cosmic rays, while additional detectors and sophisticated computer systems help weed out signals produced by ordinary matter.
But when the researchers examined the data, they found one particle interaction that stood out from the expected background.
It could potentially have been produced by a weakly interacting massive particle (WIMP) – one of the leading candidates for dark matter.
Dr Sam Eriksen, from the University of Bristol and lead author of the analysis, said: ‘Scientists have been trying to better understand dark matter, which makes up the vast majority of matter in the universe, for nearly a century.
‘What we have observed in this analysis could be the first step in understanding dark matter as a particle.
‘Following a huge amount of scientific effort, this is incredibly exciting.’
The researchers spent two years scrutinising data from the LUX-ZEPLIN (LZ) experiment, one of the world’s most sensitive dark matter detectors
However, the researchers cautioned that this is just one event – with nowhere near enough evidence to declare that they have discovered dark matter.
The result has a statistical significance of 2.6 sigma – corresponding to roughly a 0.5 per cent probability of seeing an event at least this unusual from the expected background processes.
Physicists generally require a significance of five sigma before declaring a discovery.
Professor Rick Gaitskell, from Brown University, said: ‘We’re very intrigued to see this event in the data, in the region where we expect dark matter to show up and the competing backgrounds are very low.
‘With only one event, we don’t want to get ahead of ourselves. We are not claiming to have seen dark matter.
‘But we have seen something interesting that we want to share with the scientific community for their input.’
The researchers say they have thoroughly investigated possible explanations involving ordinary matter, but have not yet found an obvious cause for the unusual event.
Dr Eriksen presented the findings at the 2026 TeV Particle Astrophysics conference in Japan.
The results have now been made available for other scientists to scrutinise and have been submitted to a scientific journal for publication.
Dark matter: The mysterious substance that makes up 27% of the universe that scientists cannot confirm
Dark matter is a hypothetical substance said to make up roughly 27 per cent of the universe.
The enigmatic material is invisible because it does not reflect light, and has never been directly observed by scientists.
Astronomers know it to be out there because of its gravitational effects on known matter.
The European Space Agency says: ‘Shine a torch in a completely dark room, and you will see only what the torch illuminates.
Dark matter is a hypothetical substance said to make up roughly 27 per cent of the universe. It is thought to be the gravitational ‘glue’ that holds the galaxies together (artist’s impression)
‘That does not mean that the room around you does not exist.
‘Similarly we know dark matter exists but have never observed it directly.’
The material is thought to be the gravitational ‘glue’ that holds the galaxies together.
Calculations show that many galaxies would be torn apart instead of rotating if they weren’t held together by a large amount of dark matter.
Just five per cent the observable universe consists of known matter such as atoms and subatomic particles.
