Dr Rolf Landua, physicist at the ATHENA experiment at CERN, Geneva, Switzerland, in 2002. The ATHENA experiment is designed to produce atoms of antimatter (anti-atoms). It does this by combining positrons (antimatter electrons) with antiprotons to form antihydrogen. The antiprotons are made by a particle accelerator, and are slowed from nearly the speed of light by the antiproton decelerator (AD), allowing them to form anti-atoms. Antimatter and matter should have been formed in equal quantities in the Big Bang, and should have rapidly annihilated each other. Studying antihydrogen will provide information on why the universe is today made mainly of matter.