The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature.
On 10 September 2008, the proton beams were successfully circulated in the main ring of the LHC for the first time, but 9 days later operations were halted due to a serious fault.
On 20 November 2009 they were successfully circulated again, with the first recorded proton–proton collisions occurring 3 days later at the injection energy of 450 GeV per beam.
After the 2009 winter shutdown, the LHC was restarted and the beam was ramped up to 3.5 TeV per beam (half its designed energy).
On 30 March 2010, the first planned collisions took place between two 3.5 TeV beams, a new world record for the highest-energy man-made particle collisions.
The LHC will continue to operate at half energy until the end of 2012; it will not run at full energy (7 TeV per beam) until 2014.
Physicists hope that the LHC will help answer some of the fundamental open questions in physics, concerning the basic laws governing the interactions and forces among the elementary objects, the deep structure of space and time, and in particular the intersection of quantum mechanics and general relativity, where current theories and knowledge are unclear or break down altogether. (Wikipedia)