Seeking dark matter is akin to searching for a black cat in a dark room, says particle physicist Caterina Doglioni. This cat neither emits nor reflects light, so even with a flashlight you wouldn’t spot it, she admits.
For almost a hundred years, researchers have relied on dark matter, an invisible substance that helps justify numerous phenomena seen in astronomical observations that they can’t fully account for.
Many theories and astrophysical calculations need dark matter to be present but scientists have never, ever been able to detect it. Why is this ‘black cat’ so elusive?
Let’s begin with the established facts and the gaps in our knowledge. It’s widely accepted that all the visible matter you can observe—cats, humans, planets, stars, and galaxies—accounts for roughly 5 percent of the universe’s total content. A perplexing 95 percent remains unseen, existing as dark matter, about 27%, and dark energy, about 68%.
If there is so much dark matter out there, how come it hasn’t been detected yet?
Euronews put that question to René Laureijs, Project Scientist for ESA’s Euclid mission:
“We have seen evidence for dark matter through many astronomical observations. We think it’s a particle but we have never detected this particle and the reason for this is that we think that dark matter is a substance that does not interact at all with normal matter and, also, does not give light or any other electromagnetic radiation. That makes it extremely difficult to detect it,” he says.
Euclid is a space telescope that is due for launch in 2020 and will observe the movement of galaxies in unprecedented ways in order to track the interaction of dark matter with ordinary matter like stars. So it’s not aiming to directly ‘see’ dark matter, but to do a better job of grasping how it functions. The mission also investigates dark energy and how it plays a role in accelerating the expansion of the Universe.
Meanwhile here on planet Earth, the particle physics community, always up for a challenge, are trying their hardest catch a glimpse of this ‘black cat’ as it scampers across the dark room. Using big particle accelerators, like CERN’s Large Hadron Collider, they generate proton collisions in the hope of detecting a ‘new’ or unknown force, which could be then proven to be dark matter.
They also strive to identify dark matter directly when it’s collected by their equipment, stored far beneath the surface at LNGS, or installed high on the International Space Station. They also look for particles that could appear when dark matter collides with itself or with another particle. So far, no evidence has been found, but they remain confident they’ll catch the elusive黑猫 someday.
If they manage to obtain a hold on it, that alone might still fall short. Each technique in isolation isn’t sufficient to uncover dark matter. You require more than one approach to truly identify what dark matter is and to validate a discovery, says Doglioni, a member of the ATLAS Collaboration at CERN and Associate Senior Lecturer at Lund University in Sweden.
Different branches within the scientific community collaborate in order to find what could be considered the Holy Grail in astronomy. However, each specialist takes their own approach.
There are meetings focused on methods to identify dark matter. Researchers share their experiences at these conferences, though the detection approaches differ: those studying particle interactions come from a different field than astronomers like us who search for dark matter through observations. There is overlap, but substantial communities operate independently to uncover dark matter.
It could take decades before we truly glimpse dark matter. Yet the researchers chasing it remain confident they’ll corner the elusive feline. It may be that dark matter is exceptionally hard to detect because it’s exceedingly rare, and we simply haven’t gathered enough data yet, says Doglioni.
The plan to extend the LHC’s operation into the next decade isn’t only about keeping one experiment running. It’s about keeping a bridge to future discoveries. More data means more power to find rare events that could reveal dark matter or hidden forces. With extra time, scientists can tune detectors, cut systematic errors, and test ideas that shorter runs might miss. Long-term work also builds high-quality data that can be reanalyzed later with new theories or better computing.
Looking ahead, researchers imagine generations of machines that push energies higher or use different methods. Future colliders could use stronger beams, tighter focus, or new collision styles to raise the chance of rare events without adding too much background noise. At the same time, scientists explore smaller, purpose-built experiments that directly search for dark matter, using ultra-sensitive detectors underground or in space to catch very quiet signals that large instruments might miss.
Developing new technology is key. Advances in superconducting materials, radiation-hard sensors, and real-time data processing let us collect and study faster, noisier data with better accuracy. The story isn’t only about bigger machines; it’s about smarter machines too systems that can automatically flag interesting events, adjust search plans on the go, and share insights across international labs. With continued patience, collaboration, and tech progress, we can keep the door open to breakthroughs that may finally reveal the nature of dark matter.
