The search for dark matter It becomes more and more like a game of hide-and-seek where, as we improve our vision, the target appears to become more invisible. The last thing we tried to do to find it was drill 1,500 meters deep underground, although in the end we had a very bad result, although it did allow us to find things that we were not looking for.
The dark matter. It is without a doubt one of the great mysteries of physics. While many researchers suggest that this matter surrounds us and is the main component of the universe, others believe that we were wrong and it doesn’t exist. Although little by little evidence is emerging that it is true that it exists so that our own theories fit.
This whole mess is mainly focused on the fact that we do not have the ability to detect this matter. We know it’s there, but we don’t ‘see’ it. Something that generates a great confrontation within the world of physicistsand that is why these types of experiments try to shed light on this matter that allows us understand much better the composition of what surrounds us.
New tools. Science has exploited the LUX-ZEPLIN (LZ) experimenta very sophisticated tool built by humanity to hunt down these ghost particles. To understand it, it is nothing more than a sensor that had to be buried 1,500 meters deep, in the facilities of the Sanford Underground Research Facility (SURF), in South Dakota.
The reason? Use the rock as a shield to block the cosmic radiation that bombards the surface.
The concept. The magnitude of this experiment has undoubtedly been quite considerable, since at its core 10 tons of ultrapure liquid xenon have been housed. The theory here is that if a dark matter particle passes through the Earth, it should occasionally collide with a xenon atom that produces a tiny flash of light.
In total, the LZ has analyzed data collected for 471 daysbetween March 2023 and April 2025. A period of time that makes this the most exhaustive search that has been done so far.
The sound of silence. The main result is that no direct interaction with the particles has been detected. However, this null result is practically worth gold in the field of physics. And by not finding anything, scientists have been able to rule out a huge range of possibilities about what dark matter is and what it is not.
In short, we have been able to establish tighter margins to detect dark matter, now having the strictest limit in the world on the cross sections of dark matter particles for a very specific mass. And it is that being of such a small masswhich is why it offers so many problems when it comes to detecting them.
The surprise. The most fascinating thing about these results is not what was missing, but what appeared. Although the detector did not see dark matter, it did validate its extreme sensitivity by recording something incredibly difficult to capture: solar neutrinos.
This marks a bittersweet milestone: the experiment has officially entered what physicists call the ‘neutrino fog‘. This means that we have reached a point of such extreme sensitivity that neutrinos (that go through everything without flinching) begin to generate background noise that could be confused with dark matter. And the truth is that we are facing a big problem, since technology will have to find a way to distinguish dark matter from neutrinos.
The future. The experiment does not stop here. Although these results cover until April 2025, the official plan is to continue taking data until 2028, with the aim of accumulate more than 1,000 days of observations. And many experts continue to point to the same thing: 85% of the mass of the universe It’s dark matterand although it escapes us, we are getting closer to knowing what the universe is made of.
Images | Karo K.
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