The largest machine built by man, the Large Hadron Collider (LHC) is a particle accelerator occupying an enormous circular tunnel some 17 miles (27 km) in circumference, ranging from 165 to 575 feet (50-175 m) below ground. Situated near Geneva, it is so large that over the course of its circumference it crosses the border between France and Switzerland four times.
The tunnel itself was constructed between 1983 and 1988 to house another particle accelerator, the Large Electron-Positron Collider, which operated until 2000. Its replacement, the LHG.-was approved in 1995, and was finally switched on in September 2008. The LHC is the most powerful particle accelerator ever built and has been designed to explore the limits of what physicists refer to as the Standard Model, which deals with fundamental sub-atomic particles.
The machine uses magnets capable of accelerating protons to near the speed of light, so they can complete a circuit in less than 90 millionths of a second. Two beams operate in opposite directions around the ring. At four separate points the two beams cross, causing protons to smash into each other at enormous energies, with their destructions being witnessed by super-sensitive instruments.
The aim of causing these collisions is to produce countless new particles that simulate, on a micro scale, some of the conditions postulated in the Big Bang at the birth of the universe. Some scientists hope that results from the LHC will reveal the existence of the Higgs Boson—the so-called "God Particle" that could be responsible for the very existence of mass.
