Atomic clocks and solid walls: New tools in the search for dark matter

An atomic clock based on a fountain of atoms. (credit: National Science Foundation)

Countless experiments around the world are hoping to reap scientific glory for the first detection of dark matter particles. Usually, they do this by watching for dark matter to bump into normal matter or by slamming particles into other particles and hoping for some dark stuff to pop out. But what if the dark matter behaves more like a wave?

That's the intriguing possibility championed by Asimina Arvanitaki, a theoretical physicist at the Perimeter Institute in Waterloo, Ontario, Canada, where she holds the Aristarchus Chair in Theoretical Physics-the first woman to hold a research chair at the institute. Detecting these hypothetical dark matter waves requires a bit of experimental ingenuity. So she and her collaborators are adapting a broad range of radically different techniques to the search: atomic clocks and resonating bars originally designed to hunt for gravitational waves-and even lasers shined at walls in hopes that a bit of dark matter might seep through to the other side.

"Progress in particle physics for the last 50 years has been focused on colliders, and rightfully so, because whenever we went to a new energy scale, we found something new," says Arvanitaki. That focus is beginning to shift. To reach higher and higher energies, physicists must build ever-larger colliders-an expensive proposition when funding for science is in decline. There is now more interest in smaller, cheaper options. "These are things that usually fit in the lab, and the turnaround time for results is much shorter than that of the collider," says Arvanitaki, admitting, "I've done this for a long time, and it hasn't always been popular."

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