Geneva: Scientists hope to fire the first beam of protons around a 27-kilometer (17-mile) tunnel on Wednesday in science's next great step to understand the makeup of the universe.

The Large Hadron Collider -- built since 2003 at a cost of $3.8 billion -- will provide scientists with much greater power than ever before to smash the components of atoms in a bid to see how they are made.

The startup has been eagerly awaited by 9,000 physicists around the world who will conduct experiments here, though some skeptics have criticized the experiment, saying they fear the collisions of protons could eventually imperil Earth.

The skeptics theorize that a byproduct of the collisions could be micro black holes, subatomic versions of collapsed stars whose gravity is so strong they can suck in planets and other stars.

"It's nonsense," said James Gillies, chief spokesman for CERN, the host European Organization for Nuclear Research.

-Abhiz