Minerals aren’t the only prize in a mine—scientists travel underground to search for elusive dark matter, the invisible substance that may make up 95% of the universe’s mass, the Wall Street Journal reports. Delicate equipment seeks to detect the stuff in the form of particles known as wimps. Above ground, such tools would pick up too many distracting signals, so down the mine they go.
These subterranean scientists have been at it for decades in Europe and in Minnesota. Picking up on dark matter would provide clues to the origins and future of the universe. But it’s not an easy task. Wimps could be flying by constantly without hitting anything on Earth, giving out only a weak signal. And if the search remains fruitless, science may be forced to decide they don’t exist at all.