A woman reads under a symbolic LHC tunnel at the entrance of the European Centre for Nuclear Research, CERN, near Geneva, Switzerland, on Wednesday. (Martial Trezzini/Associated Press)

The giant particle accelerator near Geneva, Switzerland, has completed its first major tests, successfully sending beams of protons all the way around a 27-kilometre underground tunnel beneath the Swiss-French border.

It was the first of many steps for the Large Hadron Collider, a massive physics experiment built at a cost of $3.8 billion and with a total expected cost of over $9 billion.

At 10:36 a.m. local time, the particle accelerator sent a beam of protons running clockwise through the underground circuit. Five hours later, scientists successfully sent a beam counterclockwise.

The collider will eventually push the protons using a ring of super-cooled magnets to speeds and energies never before reached under controlled conditions, and crash them into one another to create and detect a host of new particles.

The data from those collisions will then be sent to computer networks around the world, including in Canada, where they will be analyzed to try to reconstruct what happened during these collisions.

Scientists hope these collisions will be able to reveal previously unseen particles and give greater insight into the interactions that occurred during the first few moments of the universe.

The European Organization for Nuclear Research, which operates the collider and is known by its French acronym CERN, said the LHC has so far operated as expected, helping to dampen speculation that the collider would lead to some form of cataclysmic event.

Last week, the safety assessment group for the LHC published a review that dismissed fears that the collider would create universe-gobbling black holes or anti-matter destroying the Earth.

If particle collisions like the ones created at the LHC had the power to destroy the Earth, such interactions would have wiped out the planet long ago, the group wrote last Friday in the Journal of Physics G: Nuclear and Particle Physics.

"Nature has already conducted the equivalent of about 100,000 LHC experimental programs on Earth — and the planet still exists," they wrote.

Leading scientists such as Britain's Stephen Hawking have also declared the project's experiments safe.

The collider is expected to be the most powerful tool yet for physicists hoping to uncover the secrets behind the laws of the universe, both on the tiny scale of quantum mechanics and the huge domain of galaxies and black holes.

One thing in particular they believe they will find is the Higgs boson, a particle thought to impart mass on most other particles. The Higgs boson plays a key role in the Standard Model of particle physics, a framework that has helped to explain the interactions of particles like electrons, quarks and photons for over 30 years. But so far it has never been found.

Cliff Burgess, a physics and astronomy professor at McMaster University in Hamilton and associate member of the Waterloo, Ont.-based Perimeter Institute, said if the LHC can't find it, physicists will have to revisit what they think they know about the makeup of the universe.

"That's actually the best-case scenario for people like me, because that means the theorists are all in business again," he said.