Cosmic radiation—mostly protons traveling at very high speed—constantly bombards the earth, creating a shower of secondary particles, including muons. Deep underground laboratories shield sensitive physics experiments from this cosmic noise. Italy, Japan, Canada and China currently have the largest, deepest underground labs, where scientists are looking for answers to fundamental questions, such as why matter exists and how the universe evolved. Now, the Sanford Underground Research Facility, the deepest underground laboratory in the United States, is helping answer those questions. Our research includes experiments to explore the properties of subatomic particles called neutrinos and search for a mysterious substance called “dark matter”—the dominant form of matter in the universe that, so far, remains undetected.