Fifteen years of research and construction culminated on Sept. 10, when the Large Hadron Collider located near Geneva, Switzerland performed its first test run.
The machine will allow scientists to probe the nature of matter at extremely high energies, which will allow testing of current theories and reshaping of our understanding of the universe.
Some have labeled the LHC as one of man's greatest scientific achievements. Others hope it will answer the questions that people have pondered for centuries: How did the Universe begin? What is the nature of matter?
Others believe the particle accelerator is a doomsday device, one that will cause the Earth to be swallowed up in a black hole. What is the Large Hadron Collider?
On the first day of operation, scientists fired two beams of particles called protons around the tunnel in opposite directions. Though the particle collider will not be fully operational until the end of 2008, scientists hope to begin low-energy collisions within the next few weeks.
Eventually, scientists will steer and collide these two proton beams at allotted points around the tunnel at speeds close to that of light.
The $4 billion project has been plagued with numerous difficulties, including cost overruns, equipment trouble and construction problems. The first test run is two years late. However, scientists hope the rewards will be great.
The first question scientists hope to tackle is a deceptively easy one: What is mass? While this basic variable occurs in a plethora of physics equations, physicists still do not understand what causes this fundamental property of matter.
In comes the Higgs boson. First theorized in 1964, the Higgs boson has been nicknamed the "God particle." The particle is believed to carry an all-pervading field.
When particles interact with this field, they acquire their mass. While seemingly simple, the particle has been elusive. No experiment has yet proven the existence of the particle.
Physicists hope that the high-energy collisions that will be created by the LHC will "force" the Higgs boson out of "hiding," allowing them to observe it.
Some scientists, however, hope that the Higgs boson will not be found. Stephen Hawking recently placed a $100-bet on the famed particle not existing, arguing that much more interesting physics will be found by the LHC.
Though the discovery of the Higgs boson would be a massive leap forward in our understanding of matter, it will not be enough to help us understand the overall composition of the Universe.
Recent astronomical observations suggest that ordinary matter - the same matter that we see in the world around us, that make up the stars and planets - makes up just four percent of the Universe.
What makes up the other 96 percent then? Physicists argue that the rest of the Universe consists of dark matter and dark energy, which are "dark" because they have not been directly observed.
Scientists lack a full understanding of either component. The hope is that the LHC will provide clues to the fundamental nature of these two components.
The LHC may also provide a better understanding of the four fundamental forces that govern the Universe: electromagnetism, the two nuclear forces and gravity.
Physicists have been able to unify the three of the forces into a single cohesive theory. However, the fourth force, gravity, has remained elusive.
While several theories have been proposed that might unify these four forces, the one that has garnered the greatest attention is string theory.
The theory argues that the Universe consists of these one-dimensional vibrating "strings." These vibrations are what give matter its properties, determine the fundamental constants of the Universe and govern the four forces that control it.
There is one caveat to this theory: In order for these strings to occur, there need to be, in total, around 12 dimensions. Compare that to the four that we experience in everyday life: length, width, depth and time. Proponents of the theory hope that the LHC may provide a window into these alternate dimensions.
The LHC has not, however, been fully welcomed. In 2001, Greg Landsberg at Brown University and his colleague Savas Dimopoulos at Stanford University calculated that, if string theory is true and multiple dimensions other than the four already known exist, then there is a chance that the particle accelerator could produce mini-black holes.
The fear is that these black holes could destroy the Earth. However, chances are quite small such an event could occur. The lifespan of these events has been calculated to be about a billionth of a trillionth of a trillionth of a second.
"If you produce mini-black holes, then the mass of them would be less than the mass of the proton," said Bruce Barnett, a professor in the Department of Physics and Astronomy. "So the gravitational attraction of these black holes will be very small."
