The universe is full of mysteries that scientists have not yet been able to solve. And a big one has to do with what the universe is actually made of.
Now physicists from the University of Washington are taking a big swing at answering that question.
All matter exerts gravitational force. The more mass the object has, the greater the force.
Yet, a fundamental scientific problem with the universe is that there’s way more gravity than there should be. Basically, there’s not enough visible objects like stars, planets, and cosmic dust to create the amount of gravity that’s been observed on the galactic scale.
One theory for the extra gravity is that there’s a ton of matter out there in the universe that we can’t see. Fittingly, it’s referred to as dark matter.
Researchers install the copper box containing the detector modules. Surrounding the box is shielding made of lead from ancient Rome — the team chose lead so old that any radioactive contaminants within it would have already decayed.
Courtesy DAMIC-M Collaboration
Just like the Earth pulls on us, dark matter pulls on everything around it.
But using the term ‘dark matter’ is a little like saying something is a ‘Hostess snack cake’; we know generally the role it will fill in satisfying our sweet tooth, but specifically, are we talking about a Twinkie, Zinger, Snoball or Ding Dong? Or some combination of those treats?
With dark matter, no one knows. While researchers have spotted what they believe are areas of dark matter in space (one as close as in the Milky Way itself), no one has figured out what dark matter actually is.
There are currently several theories bouncing around (including WIMPs, axions, and hidden-sector particles), and the UW researchers have built a dark matter detector that can identify, or at very least, narrow the list of possibilities down.
“[Our detector] may be our best shot to answer the dark matter question in the coming years,” UW physicist Alvaro Chavarria said in a university release.
In collaboration with an international team, the physicist made a prototype dark matter detector. The detector is designed to create a snapshot of the moment a particle of dark matter hits one of the tiny particles in the detector. The prototype is designed to detect the smallest kinds of particles.
They’ve been running their detector at an underground lab a mile below the French Alps to ensure it gets a clean signal when and if dark matter passes through.
“We’re looking for very rare signals in the detector — maybe on the order of one signal in a year,” Chavarria said. “You need to remove all types of interference from other forms of radiation.”
The researchers ran their detector for 84 days and did not get a positive hit. But they say that lack of detection is very telling – not about what dark matter is but what it likely isn’t. The result starts to narrow down what flavor of particle dark matter is most likely to be.
The team plans to deploy a larger, more sensitive detector in early 2026.
The research is published in the journal Physical Review Letters here.
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