Scientists launching monster smash today

GENEVA — Scientists will launch an experiment in a tunnel deep beneath the French-Swiss border today, hoping to find evidence of extra dimensions, invisible "dark matter," and an elusive particle called the "Higgs boson."

And although leading physicists such as Stephen Hawking say the atom-smashing experiment will be absolutely safe, some skeptics fear the proton collisions could unleash microscopic black holes that would eventually doom the Earth.

The most powerful atom-smasher ever built will produce collisions of protons traveling at nearly the speed of light in the circular tunnel, giving off showers of particles that will provide more clues as to how everything in the universe is made.

In the $10 billion project — the most extensive physics experiment in history — the Large Hadron Collider will come ever closer to re-enacting the "big bang," the theory that a colossal explosion created the cosmos.

The project, organized by the 20 member nations of the European Organization for Nuclear Research — known by its French initials CERN — has attracted researchers of 80 nationalities. Some 1,200 are from the United States, an observer country that contributed $531 million.

The collider is designed to push the proton beam close to the speed of light, moving around the 17-mile tunnel at 11,000 times a second at full power. Ramping up to full power is probably a year away.

Smaller colliders have been used for decades to study the atom. Scientists once thought protons and neutrons were the smallest components of an atom's nucleus, but experiments have shown they were made of still smaller quarks and gluons, and that there were other forces and particles.

The CERN experiments could reveal more about "dark matter," antimatter and possibly hidden dimensions of space and time. It could also find evidence of the hypothetical particle — the Higgs boson — which is sometimes called the "God particle." It is believed to give mass to all other particles, and thus to matter that makes up the universe.

The two beams of protons will travel in two tubes about the width of fire hoses, speeding through a vacuum that is colder and emptier than outer space. Their trajectory will be curved by supercooled magnets — to guide the beams. The paths of these beams will cross, and a few protons will collide. The two largest detectors — essentially huge digital cameras weighing thousands of tons — are capable of taking millions of snapshots a second.