Muon Imaging - What Is It?

Researchers use the amount of muons to infer what the interior of a large space like a pyramid is like. Muon radiography was first used in 1971 to look inside the pyramid of Chefferton. It's been used outside of archaeology and geology to study volcanoes. And I found out one other application just before the show. The Defense Threat Reduction Agency said if you put five tons of lead around, people are going to smuggle it.