The largest collider in the world

The Large Hadron Collider (LHC) started operations in September 2008. Located deep underneath the Swiss and French countryside on the outskirts of Geneva, the collider is the largest and highest energy particle collider ever built.

It occupies a 27-kilometre-long circular tunnel, in which state-of-the-art magnets focus and accelerate a clockwise and anticlockwise beam of protons – positively charged subatomic particles – to almost the speed of light.

Dotted around the tunnel are large caverns, each housing a particle detector. In the heart of those detectors the two proton beams are brought together in collisions seven times more powerful than any that physicists have produced before.

At those unprecedented energies, physicists hope they can for the first time produce sub-atomic particles so unstable that they haven't been seen in large numbers since the first second of the Universe's existence. The detectors will sift through the sub-atomic debris to search for evidence of those exotic particles – the evidence physicists need to arrive at a better understanding of the basic forces that have shaped our Universe since the beginning of time, and that will determine its fate.

Despite centuries of study, the Universe is still a confusing place. Scientists have produced microscopes powerful enough to observe individual atoms – but they still don't know why those atoms have mass. Research has revealed that the Universe sprang into existence in the Big Bang 13.7 billion years ago with the formation of equal amounts of matter and antimatter – yet today most of that antimatter seems to have disappeared.

The LHC should help to explain some of these mysteries.

An artistic impression of an LHC dipole magnet, used to focus the proton beams within the LHC. Above is the tunnel (in red) marked on a plan of the Swiss and French countryside (original image here).