The Large Hadron Collider is the largest machine in the world. It is located in a tunnel over 17 miles in circumference, 574 feet beneath the ground, under the France and Switzerland border, near Geneva. It was constructed by CERN between 1998 and 2008 in a collaborative effort between more than 100 countries, hundreds of universities and labs, and over 10,000 scientists. The LHC is the largest and highest energy particle collider in the world. Presently it is at the tail end of a two year shut down for upgrades.
The LHC is outfitted to do several different kinds of research. Generally it collides two beams of particles. There are four crossing points, each with seven detectors for different fields of study. The purpose of the detectors is to test predictions, theories, and unsolved predictions of particle physics. Most of the collisions that are run are proton beams pushed near the speed of light. Heavy ion collisions such as lead are also run.
The LHC was designed to run for at least twenty years, with several planned stops for maintenance and upgrades along the way. In 2008 it achieved its first beam. In 2009 the first particle collisions were run. Late in 2009 the LHC achieved the world record for beam energy at 1.18 teraelectronvolts (TeV). In December of 2009 it broke a world record for particle collisions at 2.36 TeV, which produced significant quantities of data. In 2010 the first beams of 3.5 TeV were produced along with the first high energy collisions at 7 TeV. In 2010 the first lead-ion beams were collided. In 2012 the first collisions at 8 TeV. In 2012 CERN announced the groundbreaking discovery of a Higgs Boson like particle, a spinless subatomic particle. In 2012 the LHC announced it had reached its goal of producing a million billion collisions. In 2013 the last beams were absorbed before the scheduled end of Run 1, which began the Long Shutdown One for maintenance and upgrades. In 2013 the Physics Nobel Prize was awarded to François Englert and Peter Higgs for the “theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles,” which was confirmed by the discovery of the Higgs Boson particle.
Physicists aim to use the LHC to answer questions about the fundamental relationship of quantum mechanics and general relativity. Other studies at the LHC produce new knowledge about basic laws of fundamental physics and elementary objects, as well as the deep structure of space and time. Some of the open questions the LHC aims to answer are: What is the origin of mass? What are dark matter and dark energy? How does the quark-gluon plasma give rise to the particles that constitute the matter of our universe? Will we discover evidence for supersymmetry? Why is there far more matter than antimatter in the universe?