Evidence of Dark Matter Could Have Been Hiding for Billions of Years—Inside Ancient Rocks

• The search for dark matter is the sole obsession of many scientists and laboratories around the world.

• While some laboratories search the stars or delve deep underground, a new technique will attempt to trace evidence of dark matter collisions in ancient Earth rocks.

• A new lab at Virginia Tech will work with special microbiology imaging technology at the University of Zürich to attempt to identify crystalline “destruction” caused by dark matter effects.

The search for dark matter is an all-encompassing one, and that’s understandable—after all, 85 percent of reality is made up of the stuff, and you’ve never seen it. That’s a fair reason to be concerned with finding it as soon as possible. In their search, scientists have probed the stars in search of potentially high concentrations of axions (a leading dark matter candidate), hunted for the elusive particle in Earth’s atmosphere, and even delved deep underground in search of any hints. Now, scientists from Virginia Tech and other international universities are leading another kind of search with a decidedly low-tech focus: really old rocks.

After being awarded $3.5 million from the National Science Foundation (as well as additional funds from the National Nuclear Security Administration), Virginia Tech’s Patrick Huber and his team are building a new lab to test their new dark matter theory. As its name suggests, dark matter is currently imperceptible to modern science because it’s believed to be a weakly interacting particle. But there is an overwhelming amount of indirect evidence pointing to its existence, such as the Cosmic Microwave Background and galaxy rotation.

This isn’t a direct observation of dark matter, but there is a very strong hint that these theoretical particles exist. And while there are competing theories that attempt to explain away dark matter (Modified Newtonian dynamics, etc…), dark matter and dark energy are still the best theories we have on trying to explain the phenomena we see throughout the universe.

So, where exactly do old rocks come in? Well, as a dark matter detector, the Earth has one big thing going for it—it’s very old. Over the course of its 4.6 billion years, it’s more than likely that ancient rocks interacted with dark matter, thereby altering their crystalline structures. Huber and his team set out to find evidence of those long-ago atomic alterations.

Huber admits, however, that the idea is an ambitious one. “It’s crazy,” he said in a press statement announcing the project. “When I first heard about this idea, I was like—this is insane. I want to do it. Other people in their midlife crisis might take a mistress or get a sports car. I got a lab.”

These “miniature trails of destruction,” as the researchers call them, are caused by high-energy particles bouncing off the nucleus inside a rock, which knocks that nucleus out of place. The resulting gap leaves lasting changes to the rock’s crystalline lattice that Huber’s group hopes to identify.

“We’ll take a crystal that’s been exposed to different particles for millions of years and subtract the distributions that correspond to things we do know,” Vsevolod Ivanov, a researcher at Virginia Tech National Security Institute, said in a press statement. “Whatever is left must be something new, and that could be the dark matter.”

To track these dark matter trails, the team is partnering with the University of Zürich to retrofit microbiology imaging technology usually used for mapping animal nervous systems to possibly spot high-energy particle tracks in the rock. The entire experimental process is still being worked out, but this new laboratory will undoubtedly provide yet another exciting method for detecting the universe’s most important particle.

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