Researchers may have spotted the first signs of a dark matter particle. If the result is confirmed, it could be one of the most monumental discoveries in the history of physics.

Dark matter makes up about 85 per cent of matter in the universe, but for decades physicists have been unable to determine what it itself is made of. Hypotheses have ranged from different sorts of particles and forces to strangely behaving gravity and everything in between – but the leading idea has always been that of the weakly interacting massive particle, or WIMP. As we have built more and more powerful detectors to search for WIMPs, though, their failure to show up has led many to doubt their existence and move on to more exotic ideas.

That doubt may soon come to an end. A new analysis of data from the LUX-ZEPLIN (LZ) experiment in South Dakota has revealed a single particle that may be the first WIMP ever detected. “This result is certainly an exciting one, because it provides some potential positive hint for what dark matter could be, not just what dark matter could not be,” says at Brown University in Rhode Island, who wasn’t part of the analysis.

LZ looks for dark matter using a 7-tonne tank of liquid xenon, surrounded by several layers of shielding and buried more than a kilometre down to keep out other types of particles. When an outside particle hits a xenon atom, it creates a tiny burst of light that is measured by sensitive detectors surrounding the tank. Researchers can then use that light to reconstruct the path of the incoming particle and the energy level of the interaction.

In the search for WIMPs, we generally look for events with energies below about 30 kiloelectronvolts (keV), says LZ spokesperson , also at Brown University. That assumes the simplest sort of interaction, in which the WIMP is essentially bouncing off an individual nucleon in the xenon nucleus. Having not found any hints of WIMPs in that energy range, the LZ team decided to reanalyse the first 220 days of data from the detector, searching for events with higher energies.

That is where they found their dark matter particle candidate, at about 248 keV. “You must never make an assumption that nature is going to do something the easy way,” says Gaitskell. “Nobody can accuse our universe of making the simplest and most natural-seeming choices.”

Such a high-energy event can’t have come from the most simple type of interaction between a WIMP and a nucleon – instead, it must have happened through a more complicated coupling between the WIMP and the entire xenon nucleus. If that is the case, the WIMP must have a mass more than 200 times the mass of a proton.

“It’s not just that they’re seeing something, but that there’s a hint at what the underlying mechanism might be,” says at the University of California, Berkeley, who wasn’t involved in the analysis. “If this all stands up, our learning curve is going to be pretty steep from now on.”

Actually detecting a dark matter particle could reveal some of the universe’s most closely held secrets, including information about the early universe that is otherwise nearly impossible to determine, and drastically shake up our standard model of particle physics. But as Haxton says, this detection is not yet certain.

In particle physics, the statistical threshold for a finding to go from an intriguing hint to a solid discovery is a number called 5 sigma, which means there is about a 1-in-3.5 million chance that a signal like this would show up as a fluke rather than a true sign of dark matter. Right now, this detection from LZ sits at 2.6 sigma, which means that there is about a 1-in-200 chance it could appear as a fluke.

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That might still seem fairly secure, but in the search for dark matter it is far from enough. “In science we sit down and we do so many damned experiments, I’m afraid you come across a 1-in-100 event fairly often,” says Gaitskell.

“Before one can declare victory, you need a few more data points, but now they have something to aim for, they know where to look,” says Haxton. The good news is that this analysis only covered about one-third of the data that LZ has already taken, and other dark matter detectors around the world have their own data, as well. A few more events in the same energy range could bump the discovery of WIMPs up to 5 sigma – and change our understanding of physics and the universe forever.

If I could go back in time and tell my younger self something about life as a theoretical physicist, I might say: mind the gap between what’s exciting about physics and what the job actually is. My new book, , was born in part out of thinking about the physical questions that get pushed to the margins in professional physics. Big-picture questions like, what is the material nature of space? What is a quantum theory of time? It is very difficult to build a professional life working on these questions – even as books tout them as the most exciting ones in the universe.

I was recruited into the world of physics by the Errol Morris documentary about Stephen Hawking, A Brief History of Time. Eventually, I read Hawking’s book of the same name and my impression of a working life in physics was that, for the most part, physicists think big thoughts about wonders of the universe every day.

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Today, I’m a tenured professor of physics at a major research institution, and a lot of my job is sending emails about bureaucratic things, like asking whether anyone can tell me the policy that is governing changes that the university is making to my grant. On a good day, I get to have conversations about science with the postdoctoral fellows I employ in my research group – but that’s not every day. And in either case, the kind of research that we can get grant funding to do is quite limited. The sort of work Hawking did on the nature of time is financially out of reach for most physicists, a situation that is getting worse as the UK and the US both slash and burn basic science budgets.

The Edge of Space-Time was born in this gap between what we say science is and the reality of living it. I began it at a moment of transition. I had just been awarded tenure, which, in the US, historically has meant my position is permanent, and I am free to research whatever interests me without worrying about being fired. At the moment my tenure became official, I was thinking about what I had given up to get there, the strategic choices I had made.

I gave up working on quantum gravity, for example, both because of racism I experienced as a PhD student and because the job prospects weren’t good. I never took a class where we were asked to think deeply about time, space and the fundamental nature of space-time. Mostly, I learned to calculate and pursue questions that were broadly agreeable to the physics community, like understanding the nature of dark matter. And while I think these questions are important and interesting, they live at a kind of margin that physicists are pushed to by economic and social forces that determine which questions we can be paid to pursue and which we won’t be.

When I began working on the book in 2023, I was in the midst of a five-year stint working in US science policy, alongside colleagues from around the world (mostly the UK, Europe and Canada). As I learned more about the politics of science at the government level, it became clear to me that particle physics and cosmology were in trouble. Politicians were no longer sold on the fundamental importance of our research and didn’t see how it was beneficial to the capitalist economy or the military, which historically is how that support has been rationalised. The cultural arguments – that a well-cultured civilisation does things like try to understand the universe – didn’t seem impactful at all. And the general public, struggling with climate change and economies that don’t serve the 99 per cent, couldn’t see how we had anything to add.

I could see that we were about to be on the margins in a new way. And so The Edge of Space-Time became not just a return to my roots and the big-picture questions that once drove me, it also became a plea: don’t let me be the last of my kind. The cuts that are being made to science in the UK and the US right now seem like a political problem that is easily remedied, but it is more complicated than that. Even one year where there is a gap in funding means we haemorrhage workers who may never return. As those researchers leave, they take with them knowledge. Because the sciences work through apprenticeship, if there is no senior instructor to pass on knowledge, it doesn’t matter if there is money and an apprentice waiting in the wings.

With The Edge of Space-Time, I take readers on a journey through huge questions, like why does my favourite physics experiment foist the structures of quantum physics on us? And will we ever know what space-time really is, or is it always just going to be a useful mathematical construct that allows us to calculate motion in environments where gravity plays a significant role, like near black holes?

While thinking through the physics, I also try to make the case for why any healthy democracy needs people who live at the edge of what is known and what is unknown – the keepers of these cosmic stories that have fascinated humans for millennia. I make the case that, like poetry, physics gives us a viewpoint on the universe that we need because it is our ancestral inheritance. I also argue that spending time with what feels strange about physics can help prepare us to better reckon with difficult political questions.

Given the crises we face – genocides, climate change, attacks on transgender people – we need our critical faculties now more than ever. Thinking a bit about the various edges of space-time, like black holes and cosmic event horizons, can help us build the better world we need.

by Chanda Prescod-Weinstein (Canongate Books) is the September read for the Â鶹´«Ă˝ Book Club. Sign up for the club here, and join the discussion on Discord .

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Could our universe have more dimensions than the three of space and one of time that we experience?

Recent results from the Dark Energy Spectroscopic Instrument (DESI) have renewed interest in whether our current picture of the universe is complete. Some theories suggest that extra dimensions could help explain three of the greatest mysteries in physics: the nature of dark energy; the invisible influence of dark matter; and why gravity is so much weaker than the other fundamental forces.

From string theory to braneworlds, the search for extra dimensions pushes the boundaries of science and could reveal that the reality we experience isn’t all there is.

Mark Thomson is the newly appointed director general of CERN near Geneva, Switzerland. CERN is the world’s biggest particle physics laboratory, and its Large Hadron Collider (LHC) smashes particles together at almost the speed of light to understand the fundamental nature of the universe. CERN has been responsible for groundbreaking new physics, most notably the discovery of the Higgs boson in 2012, and is a world leader in antimatter research. However, in order to probe even deeper, it must run at higher energy levels. We catch up with Thomson at an important juncture, as the LHC is due to shut down for two years for upgrades, paving the way for even more exciting physics. But is there anything left to discover? And are large particle accelerators the future of particle physics?

“There are really big questions that we don’t know the answer to,” says Thomson. “Big questions like dark matter. Is the Higgs boson a fundamental particle? Does the Higgs boson interact with the dark matter? At some point, we are going to find answers to some of these really, really big questions.”

Read more: The experiments that could finally explain gravity

Deep beneath the planet’s surface at the Sanford Underground Research Facility in South Dakota, scientists are waiting for something that may never happen – the interaction of weakly interacting massive particles, or WIMPs. This is LUX-ZEPLIN, the most sensitive dark matter detector on Earth.

WIMPs are a leading contender for dark matter and could answer one of the biggest mysteries in cosmology: where is the missing matter that makes up the universe? The detector is filled with 10 tonnes of ultra-pure liquid xenon and is so sensitive that even a single gram of dust would skew its results. A single collision could reveal what most of the universe is made of, or prove that decades of physics may be pointing us in the wrong direction.