In underground lairs, physicists look for the dark stuff
On an early summer morning in northern Minnesota, a crew of about a dozen waits by the top of mine shaft No. 8. Donning hard hats, the engineers and physicists pile into a creaky, double-decker elevator cage. It is pitch black for most of the three-minute descent. Ears pop, the cage floor vibrates and a giant motor dating from 1925 thunders overhead.