GENEVA — A small blip on a computer screen sent champagne corks popping among physicists in Switzerland. Near Chicago, researchers at a “pajama party” who watched via satellite let out an early morning cheer.

The blip was literally of cosmic proportions, representing a new tool to probe the birth of the universe.

The world’s largest atom smasher passed its first test yesterday as scientists said their powerful tool is almost ready to demonstrate how the tiniest particles were first created after the “big bang,” which many theorize was the massive explosion that formed the stars, planets, and everything.

Rivals and friends turned out in the wee hours at Fermilab in Batavia, Illinois, in pajamas to watch the event by a special satellite connection. Joining in from around the world were other physicists — many of whom may one day work on the new Large Hadron Collider.

Tension mounted in the five control rooms at CERN, the European Organization for Nuclear Research, as scientists huddled around computer screens. After a few trial runs, they fired a beam of protons clockwise around the 17-mile tunnel of the collider deep under the rolling fields along the Swiss-French border. Then they succeeded in sending another beam in the opposite, counterclockwise direction.

The physicists celebrated with champagne when the white dots flashed on the blue screens of the control room, showing a successful crossing of the finish line on the $10 billion machine under planning since 1984.

“The first technical challenge has been met,” a jubilant Robert Aymar, director-general of CERN, said. “What you have just seen is the result of 20 years of effort. It all went like clockwork. Now it’s for the physicists to show us what they can do.

“They are ready to go for discoveries,” Mr. Aymar said. “Man has always shown he wants to know where he comes from and where he will go, where the universe comes from and where it will go. So here we’re looking at essential questions for mankind.”