However, if there is some blockage in the machine, experts will have to go in and fix the problem, and that could take time.

The LHC, as the collider is known, will take scientists to within a split second of a laboratory recreation of the big bang, which they theorize was the massive explosion that created the universe.

The project organized by the 20 European member nations of CERN has attracted researchers of 80 nationalities. Some 1,200 are from the United States, an observer country which contributed US$531 million. Japan, another observer, also is a major contributor.

The collider is designed to push the proton beam close to the speed of light, whizzing 11,000 times a second around the tunnel.

Smaller colliders have been used for decades to study the makeup of the atom. Less than 100 years ago scientists thought protons and neutrons were the smallest components of an atom's nucleus, but in stages since then experiments have shown they were made of still smaller quarks and gluons and that there were other forces and particles.