A stack of CDs as high as Mount Royal would hold about 30 years worth of music. The ATLAS detector at the Large Hadron Collider generates that much data in less than two seconds. But thanks in part to a group of McGill physicists, ATLAS won't be filling up all of the world's hard drives. ATLAS is used to observe collisions between protons travelling near the speed of light. It is the largest of six detectors at the Large Hadron Collider - the most powerful particle accelerator ever created, located in a 27-kilometre-long circular tunnel beneath the Franco-Swiss border near Geneva, Switzerland. Researchers from 37 countries work with ATLAS, including four physics professors from McGill University: François Corriveau, Steven Robertson, Brigitte Vachon and Andreas Warburton.