Scientists at CERN took some antiprotons out for a spin in a never-tried-before test drive. Tuesday's experiment was hailed as a success. About 100 antiprotons traveled in a truck around CERN's Geneva campus and were transported back into the lab. Each particle had corresponding antiparticle, like an antiproton, exactly matching the particle but oppositely charged. If the opposites came into contact, they would “annihilate” each other and set off energy. The mass in the test was tiny, so the worst that could happen was losing the antiprotons.