Technicians use a lift in the ATLAS (A Toroidal LHC ApparatuS) experiment during a visit at the Organization for Nuclear Research (CERN) in Meyrin, near Geneva April 10, 2013. As hundreds of engineers and workers start two years of work to fit out the giant LHC particle collider to reach deep into unknown realms of nature, CERN physicists look to the vast machine to unveil by the end of the decade the nature of the mysterious dark matter that makes up a quarter of the universe and perhaps find new dimensions of space. Picture taken April 10, 2013. To match story SCIENCE-CERN/ REUTERS/Denis Balibouse (SWITZERLAND - Tags: SOCIETY SCIENCE TECHNOLOGY)