Scientists probing something as big as the origins of the universe sometimes need equipment to match. At the European nuclear research center CERN in Geneva, they're building the most powerful particle accelerator ever. The Large Hadron Collider, as it's called, is expected be able to recreate the conditions that existed at the time of the Big Bang, when the universe was born. Scientists say they hope the new tool will help them unravel the mysteries of matter and energy, and confirm or demolish existing theories.

Contrary to what its name implies, the Big Bang was not necessarily an explosion. Scientists consider the Big Bang to be more of a marker to note that the universe had a beginning. It is the moment in which the universe, space and time were created. CERN Physicist Richard Jacobsson says scientists do not know why or how the Big Bang occurred. But big particle accelerators such as the Large Hadron Collider help them to understand the process.

"With our accelerators, what we aim at doing is to recreate at very, very small scales, the conditions of the Big Bang in order to study how the particles and the forces behave," he explains.

When the Large Hadron Collider (LHC) is completed in 2007, the superconducting magnets in the machine will operate at 271 degrees, just above absolute zero. However, Mr. Jacobsson says that the temperature created in the proton-proton collisions will be one billion times hotter than at the center of the sun.

"We can actually compute at which moment in the history of the universe, the universe had this temperature," he adds. "And it turns out to be a tenth of a billionth of a second. So with the LHC, we will be able to see how the universe behaved when it was no older than a tenth of a billionth of a second. And from that time, we have quite a clear idea of how the universe evolved up to today. What we are now trying to find out is what happened beyond that, earlier than that."

Some 6,500 scientists from more than 80 countries currently collaborate on hundreds of ongoing experiments at CERN. The world's biggest particle physics laboratory is celebrating its 50th anniversary this year.

The United States, which was and remains CERN's biggest competitor, is also its biggest collaborator. After Congress killed the project to build the higher energy Superconducting Supercollider in Texas in 1993, US physicists threw their talent and money into support of the LHC. This accelerator will cost nearly $2.5 billion. The United States is contributing more than $500,000 in cash and kind toward its construction.

"For going down, in principle, you have to go through a safety lock where only one person at a time can go in," explains Torsten Wengler, a physicist working at Atlas, one of the four big experiments being built at the LHC. "Now if we take visitors in, there has to be somebody with a key, either Peter or myself, where I can go through, open a door and let people through. But I cannot just go through the same door because then nobody would be registered to go down."

A group of visitors wearing fire-engine red helmets takes an elevator about 40 stories down. Mr. Wengler describes the impressive dimensions of the Atlas experimental hall. When completed, it will be about six times bigger than Notre Dame Cathedral in Paris.

"The whole cavern is 53 meters long and 35 meters high and about 30 meters wide," says Mr. Wengler. "It is about 100 meters down to the bottom of the cavern and the absolute weight of the experiment itself will be about 7,000 tons."

CERN straddles the French-Swiss border near Geneva. The LHC is being built in the same 27 kilometer tunnel previously occupied by an older, less powerful accelerator. When the LHC gets up to speed, the accelerated protons will travel with nearly the speed of light. There will be about 800 million proton-proton collisions every second.

With the LHC, physicists believe they will discover a new particle called the Higgs boson. Named after the British physicist, Peter Higgs, this particle is believed to hold the answer as to why subatomic particles have weight or mass. Mr. Wengler says finding the Higgs would be a huge success. But he says not finding it might be even more interesting.

"If we do not discover it at all, even after the end of LHC, then we have found a fundamental flaw in the theory and this might be even more exciting than finding it," says Mr. Wengler. "So we really have a win-win situation. If we find something, we have found something. If we do not find something, than we will have a very, very strong hint that something in the way that we think it works is actually different. And, that might be even more exciting."

Hundreds of computers work non-stop collecting data for future analysis. CERN is developing more advanced computing and electronic tools to keep track of the enormous number of particles the LHC collisions will produce. Unraveling these data will be a mammoth task, too big to be done efficiently in one set of computers, requiring another new technology to allow scientists worldwide to access the data.

"As you know, the Web was invented here at CERN, and now we are developing a technology - which by the way we did not invent - called the Grid, which we think is going to be the next big application of the Internet," says Francois Grey, Head of IT Communications at CERN. "What the Grid will do is give us access to computing power and data storage capacity at the click of a mouse in the same way that the web does. You do not have to know where that processing power is. You do not have to know where your data is stored. You will rely on the Grid to do that for you."

Mr. Grey says scientists will be analyzing data acquired from LHC for dozens of years. The Grid will make it possible to distribute huge amounts of data to scientists around the world.

As in the past, there are likely to be many spinoffs from the instrumentation and information technology invented at CERN to meet LHC's experimental needs. The World Wide Web, of course, is a dramatic example of a previous invention that has changed the world of information. Then again, particle accelerators have become important tools in industry, medicine and research.