The deepest dark detector

In the heart of a mountain in China's Sichuan province, underneath 2400 meters of stone, researchers are powering up the most ambitious effort yet to directly detect some of the strangest stuff in the universe: dark matter. Early this year, the PandaX (Particle and Astrophysical Xenon) experiment will start collecting data in hopes of finding evidence of the elusive particles, thought to constitute more than 80 percent of the matter in the universe.