Nestling in the foothills of the Alps is Europe's largest laboratory, the European Centre for Nuclear Research, or Cern.
The LHC has been in construction for some 13 years
A 27km chain of magnets is part of the experiment |
With its vast labyrinth of tunnels and equipment stretching for miles, the complex has the feel of a cathedral to science.
And now the scientists here have embarked on their biggest experiment ever, the hunt for a particle which gave the universe its form.
Its scientific name is the Higgs Boson, but because it is so fundamental in shaping the universe, others have called it the God particle.
It is a particle that is supposed to endow other fundamental particles with mass. Without it there would be no gravity, no universe as we know it - no "let there be light" moment.
No-one has seen it, but physicists have invoked it because it is the simplest explanation for how the universe evolved.
Spark of divinity
Most physicists are instinctively drawn towards theories with a simple elegance.
Reverend Sir John Polkinghorne used to be a theoretical physicist and worked with Professor Peter Higgs, after whom the God particle was named.
Professor Polkinghorne went on to become an Anglican priest. He believes the equations which describe the way sub-atomic particles interact contain a natural beauty in which some find a spark of divinity. 
He said: "Physicists are deeply impressed with the order of the world. It is rationally beautiful and structured, and the feeling that there is a mind behind it is a very natural feeling to have."
It is not the first time that a scientific study of the universe has inspired awe and wonder.
 |  I think the feeling of wonder, which is very fundamental to the experience of physicists...is fundamentally a religious experience, whether people recognise it as such or not  |
The crew of Apollo 8 were so moved by their experience, they felt moved to read passages from the Book of Genesis as they orbited the moon on Christmas Eve in 1968.
US physicists Richard Feynman and George Smoot both described their Nobel Prize-winning insights into the behaviour of subatomic particles and the detection of the Cosmic Background Radiation as looking "unto the face of God".
Professor Polkinghorne understands why such glimpses into the underlying reality of the universe can provoke such reactions.
He said: "I think the feeling of wonder, which is very fundamental to the experience of physicists - they way they see structure in the world - is fundamentally a religious experience, whether people recognise it as such or not.
"And I think it is actually a tacit, sometimes explicit, worship of the creator."
Many of the physicists here are not religious and would disagree with Professor Polkinghorne's view.
For them their buzz is an intellectual rather than religious one.
Explain gravity
And although the hunt for the Higgs Boson is one of the big hopes for the Large Hadron Collider, the real prize will be to roll back the frontiers of physics.
The Standard Model that has explained the behaviour of sub-atomic particles so well seems to have hit a wall.
The equations that were becoming ever more elegant tying together the fundamental forces of nature have become messy in attempting to explain gravity.
Observations by cosmologists, such as the amount of matter in the universe, cannot be explained by current theory.
Theoretical physics is bracing itself for a revolution. The results from the LHC will help scientists glimpse what lies beyond the standard model.
Scientific study is often mundane but can occasionally slip into the ecstatic.
No more so than for those working at the Large Hadron Collider.
Many of the people involved have been working painstakingly for years, developing the code, engineering the parts and putting the pieces together.
The excitement among physicists at Cern has been palpable.
It will not be long before the experiments that will change our view of the universe can begin.
They have fired a beam of particles called protons around the 27km-long tunnel which houses the Large Hadron Collider (LHC).
The £5bn machine on the Swiss-French border is designed to smash particles together with cataclysmic force.
Scientists hope it will shed light on fundamental questions in physics.
The beam completed its first circuit of the underground tunnel at just before 0930 BST.
"There it is," project leader Lyn Evans said when the beam completed its lap. There were cheers in the control room when engineers heard of the successful test.
He added later: "We had a very good start-up."
The LHC is arguably the most complicated and ambitious experiment ever built; the project has been hit by cost overruns, equipment trouble and construction problems. The switch-on itself is two years late.
The collider is operated by the European Organization for Nuclear Research - better known by its French acronym Cern.
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