FERNEY-VOLTAIRE, FRANCE -- Some particle physics experiments are easier to ride than others. The giant detectors that take pictures of particle collisions on kilometres-round rings don't really have anywhere to sit, and the intense bureaucracy would probably demand an unwieldy amount of paperwork for would-be riders. The thing that stopped me from riding the whale-sized CAST experiment, however, wasn't fear of disrupting its search for dark matter particles. It was that deputy spokesperson Giovanni Cantatore misplaced the harness.