GENEVA -- (UPDATE) Particle physicists were jubilant on Wednesday after the long-awaited startup of a mega-machine designed to expose secrets of the cosmos passed its first tests with flying colors.

Cheers, applause and the pop of a champagne cork -- rather than the cataclysmic suck of a black hole, which doomsayers had feared -- marked the breakthrough at the European Organization for Nuclear Research (known by its French acronym CERN).

Robert Aymar, the organization's director general, hailed it as a "historic day" for CERN and mankind's thirst for knowledge.

Humans have "a quest for (knowing) where they came from and where they should go, whether the Universe will end, and where the Universe will go in the future," he said.

Just after 0730 GMT, a first proton beam was injected into the Large Hadron Collider (LHC), a massive project built 100 meters (325 feet) underground at CERN headquarters and described as the biggest physics experiment in history.

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

After a series of trial runs, two white dots flashed on a computer screen at 10:36 a.m. (4:36 p.m. in Manila) indicating that the protons—a type of subatomic particle—had traveled the full length of the LHC.

The mission aims to resolve some of the greatest enigmas in physics: whether a so-called "God particle" exists that would account for the nature of mass; an explanation for "dark matter" and "dark energy" that account for 96 percent of the cosmos; and whether other dimensions exist parallel to our own.

In a 27-kilometer (16.9-mile) circular tunnel on the Swiss-French border, parallel beams of protons will be accelerated to nearly the speed of light.

Superconducting magnets will then steer the counter-rotating beams so that strings of protons smash together in four huge laboratories, fleetingly replicating the conditions that prevailed at the "Big Bang" that created the Universe 13.7 billion years ago.

Arrays of detectors will trace the sub-atomic rubble spewed out from the collision, looking for signatures of novel particles.

CERN scientists have ruled out fears that the process could create a "black hole" whose super-gravity would swallow the Earth, or a theoretical particle called a strangelet that would turn the planet into goo.

The skeptics theorized 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 spokesperson for CERN, before Wednesday’s start.

CERN is backed by leading scientists like Britain’s Stephen Hawking in dismissing the fears and declaring the experiments to be absolutely safe.

Gillies said that the most dangerous thing that could happen would be if a beam at full power were to go out of control, and that would only damage the accelerator itself and burrow into the rock around the tunnel.

Wednesday's startup marked the start of a long and cautious commissioning process to check equipment and operational procedures before these collisions can get underway.

The first batch of protons was halted, sector by sector, to verify that monitoring systems and the steering magnets were working properly. Their speed was purposely slowed for the inspection process.

The clockwise beam completed this first test lap in under an hour, causing an eruption of joy and an outbreak of bubbly in the control room.

A test of the anticlockwise beam took place later and again the operation was problem-free.

"Technically, everything works the way it should work and the path ahead is very, very clear," said Jos Engelen, the LHC's chief scientific officer.

LHC Project Leader Lyn Evans, who has been working on the collider for 14 years, said he felt a wave of relief after the protons had completed their first lap so smoothly.

"It's a machine of enormous complexity and things can go wrong at any time," he said.

Messages of congratulations flooded in from CERN's partners and rivals, including the legendary Fermilab particle physics lab near Chicago.

The LHC took nearly 20 years to complete and at six billion Swiss francs (€3.76 billion, $5.46 billion) is one of the costliest and most complex scientific experiments ever attempted.

When all is ready, the LHC will whizz the two beams around the tunnel at up to 11,000 laps per second before steering them into collisions into four chambers whose walls are swathed with detectors.

The first collisions are likely to start in several weeks, but only next year will the LHC be cranked up to its full capacity of 14 teraelectronvolts -- a massive amount of energy that will briefly generate temperatures 100,000 times hotter than the Sun. It will be seven times the record held by Fermilab.

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.

Over the 10-15 years in which will the LHC will operate, masses of data will spew from these collisions and will be scrutinized by physicists around the world.

"It's about acquiring knowledge for humanity about the behavior of fundamental matter," physicist Daniel Denegri told AFP. "We expect to make discoveries that could be rather spectacular."

"Basic knowledge is part of the heritage of humanity," added researcher Daniel Froidevaux.

The Holy Grail will be finding a theorized component called the Higgs Boson, which would explain how particles acquire mass. Believed to be ubiquitous -- yet also frustratingly elusive until now -- the Higgs has been dubbed the "God particle."

French President Nicolas Sarkozy, whose nation holds the European Union presidency, hailed Wednesday's start-up test as "a very big success for Europe."

"The spin-offs from this unprecedented scientific investment in the history of humanity are essential not only to deepen the intimate knowledge of the universe but also for direct applications in such varied areas as intensive calculations or even medicine," he said in a statement.

“I think it’s a very important project,” said Katie McAlpine, 23, a Michigan State University graduate, who made a rap video about the project.

“It’s mostly out of scientific curiosity, what is the universe made of? How does it work? What are the rules? That’s very exciting and it’s important to advance our knowledge,” she told Associated Press Television News.

She said she was surprised by the success of the video, which has had more than a million views on YouTube and which has received approval from CERN for its scientific accuracy and its success with young people.

“I was really hoping that this would get taken into classrooms,” McAlpine said. “I don’t imagine that elementary school and most middle school children will understand it very well, but a lot of parents have e-mailed me, saying I have a 9-year-old or a 7-year-old and showed them your rap and they really love it.

“If elementary kids can get excited about it, too, that’s just great.”