One hundred meters beneath the borders of France and Switzerland, near the city of Geneva, there is a tunnel, 27 kilometers around, called the Large Hadron Collider. That is where scientists are working to answer one of life’s biggest riddles: What is the universe made of? The physicists working at CERN – officially the European Organization for Nuclear Research – are looking for things like antimatter and dark matter and how the universe works. Penny Dixon reports from Geneva.