One hundred metres below Geneva's western suburbs is a dimly lit tunnel that runs in a perfect circle for 27km (17 miles). The tunnel belongs to Cern, the European Centre for Nuclear Research. Though currently empty, over the next two years an enormous experiment will be installed here. The Large Hadron Collider (LHC) is a powerful and impossibly complicated machine that will smash particles together at super-fast speeds in a bid to unlock the secrets of the Universe.
By recreating the searing-hot conditions fractions of a second after the Big Bang, scientists hope to see new physics, discover the sought-after "God particle," uncover new dimensions and even generate mini-black holes. When completed, two parallel tubes will carry high-energy particles called protons in opposite directions around the tunnel at close to the speed of light. The tunnel's huge circumference provides only the slightest of bends. Nevertheless, 5,000 superconducting magnets are needed to steer and focus the particles around the tubes. Along the way, they will pass through enormous experimental instruments called detectors where the proton beams will cross. When some of these protons collide at high energy, smaller, heavier particles can appear amongst the debris.