Scientist Rick Gaitskell, a physics professor at Brown University, talks about the Sanford Underground Research Facility in Lead, S.D. The lab's experiments will include the world's most sensitive dark-matter detector. Gaitskell says that he's been hunting for dark matter for 23 years, and that the lab — housed inside the now-shuttered Homestake Gold Mine nearly 5,000 feet beneath the earth — could help scientists understand the origins of the universe.