UC Berkeley researchers help develop theory on dark matter’s mass, interactions

Kavli IPMU/Courtesy
In this artist's rendering of dark matter distribution, the left side represents a conventional theory, where dark matter is most concentrated in the center of a galaxy. On the right, dark matter spreads out from the center of the galaxy according to the new theory.

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A team of researchers has proposed a theory that dark matter is made up of particles similar to those that hold atomic nuclei together.

The five researchers, two of whom are from UC Berkeley, propose that dark matter particles are less massive and interact with one another more than previously thought.

Dark matter makes up 25 percent of the energy and 85 percent of matter in the universe, “and yet we know nothing about it,” said Eric Kuflik, a postdoctoral scholar at Cornell University and co-author of the paper.

“Dark matter is something we owe our existence to,” said Hitoshi Murayama, a UC Berkeley physics professor who co-authored the paper. “We don’t know what exactly it is yet — it’s not made of the atoms we’re made of.”

Kuflik said that the research group is “not at all” sure this theory is correct but that it could explain some phenomena other theories cannot.

According to UC Berkeley postdoctoral researcher Yonit Hochberg, who also contributed to the paper, scientists won’t be able to prove this theory on dark matter until they are able to observe dark matter in a lab.

The theory is changing the way scientists attempt to isolate dark matter, as it suggests that they should be looking for less massive particles, Hochberg said.

“In the next five or 10 years, we could very well have discovered the dark matter we’re proposing,” she said. “The paper is getting a lot of attention. … The more people start thinking outside the box, the sooner we’ll find dark matter.”

Though Kuflik said scientists are unsure what practical implications will come out of discovering more about dark matter, “it’s one of the biggest mysteries in the universe,” he said. “That’s what makes it so much fun.”

Yasunori Nomura, a physics professor at UC Berkeley who did not contribute to this research, said that while similar theories have been proposed in the past, this paper “has some explicit theorization of how this can happen.”

“It’s very hard to guess what is the right theory because we know very little of dark matter,” said Leonardo Senatore, an assistant professor of physics at Stanford University who described the theory as more of a paradigm than a specific model.

The research group has also published a paper on how dark matter particles collide and reduce, and according to Hochberg, the group plans to publish within the next few months another paper on the ways in which dark matter interacts with ordinary matter.

“It’s a really cool topic to work on,” Hochberg said. “We’re all enthusiastic about continuing to work on it.”

Contact Sally Littlefield at [email protected] and follow her on Twitter at @slittlefield3.