Dark matter is thought to make up a little over a quarter of the universe. That’s six times more than all the matter ever observed. And, yet, dark matter is called that because it’s a mystery.
Its identity is unknown and it’s never been observed. That’s not for lack of trying. Millions of dollars have been poured into detectors around the world.
Now, the failure of those purpose-built detectors to find what they were looking for is sparking a revolution in particle physics.
"We now have a long list of reasons why we know deep in our hearts that dark matter exists," said Flip Tanedo, assistant professor of physics at UC Riverside. "And if it does not exist, then something really really tremendously crazy is going on."
Tanedo is in a cadre of physicists who were earning their doctorates at the same time the Higgs boson was discovered in 2013.
"We were all educated thinking that the next big thing in particle physics would be discovered at a collider," Tanedo said. "We would discover supersymmetry or extra dimensions or all of these exotic new particles."
That didn't happen.
"It seemed like, 'Oh actually, the Large Hadron Collider discovered the thing which we knew ought to be there -- and nothing else," he said.
That was a disappointment.
"I'm not going to lie. A lot of us you know had a few drinks after that," Tanedo said.
But it was also an opportunity to reconsider all of the previous efforts to find dark matter.
"Now people are looking for -- what if dark matter is much, much heavier? Or what if dark matter is much, much lighter?"
Maybe we shouldn't even be looking for dark matter in the lab, he said.
"So, with colleagues from the National Lab in Canada (TRIUMF) and Queen's University, we've been thinking about what happens in the early universe. If we know dark matter had to be there to be the seed for our our galaxy to form, maybe the fact that dark matter was around would leave some kind of imprint on the stars."
With new telescopes that are looking further back in time, perhaps that imprint can be discerned and we can distinguish different types of dark matter models, Tanedo said.
"Now we're starting to think maybe we should be speaking more to our astronomy colleagues, maybe our condensed matter colleagues," he said. "It's been really a fruitful time for us to think outside of the usual particle physics box and kind of redefine what the field is is becoming."
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