They're looking for answers to simple questions, really.

Like, what happened moments after the Big Bang?

This morning, about 109 yards underground near the border of France and Switzerland, a proton beam circulated the Large Hadron Collider, a ring with a circumference of 17 miles.

Particle physicists around the world applauded, among them a team of physicists at the University of Illinois who study "the most fundamental particles that make up the universe," according to UI physics Professor Tony Liss.

"This is a huge deal in the world of particle physics. Everybody is excited," he said.

Chemists study atoms and molecules. Particle physicists study quarks and leptons and their interactions.

Quarks? Leptons?

You may remember from high school science class that atoms are made of protons, neutrons and electrons. Protons and neutrons are made of quarks.

(There are six different types of quarks, including the "top quark" which was discovered, with the assistance of UI physicists, at Fermilab in Batavia.) Then there are leptons, which include electrons and muons, which UI physics Professor Steve Errede described as the heavier cousin to the electron.

And don't forget the elusive Higgs boson particle, the particle that according to some theories is responsible for giving other particles their mass, Liss said.

With the new superpowerful collider, physicists will be looking for the Higgs boson and other particles.

"We're interested in trying to understand the nature of these forces," Errede said.

Liss, Errede and two other UI physicists, Debbie Errede and Mark Neubauer, are all part of the ATLAS detector project, an experiment involving 2,500 physicists from around the world that looks into the fundamental nature of matter and the forces that shape the world.

The European Organization for Nuclear Research's (or CERN's) Large Hadron Collider is capable of essentially recreating conditions just after the "Big Bang."

The collider "circulates counter-rotating beams of protons at high energy," Errede said. There, scientists will accelerate the particles and produce collisions at seven times the energy of the particle accelerator at Fermilab.

"It's huge. It opens up all kinds of new possibilities," Liss said.

Consider this. Bunches of about 100 billion protons (protons which have 7 trillion electron-volts of energy) will collide at a rate of 40 million times per second.

When a proton from each beam collides with another one, there's a kind of spray of all kinds of particles produced in that collision, Errede said.

Although the first proton beam was circulated today, it's still a fairly lengthy process to get the counter-rotating beams to collide, Liss said.

"The hope is that will happen in October," he said.

The ATLAS detector, at about 49 yards long, has been set up along the collider's ring and will gather data while these collisions take place, Liss said.

Researchers will use the information gathered in the detector to find out what happened in the collisions, what kinds of particles are produced and how they interact.

Here on the UI campus, physicists, engineers and local welders helped build what's called the ATLAS Tile Calorimeter, part of the detector that will measure the energy of these particles.

The UI physicists will also be involved in the years to come.

The Large Hadron Collider experiments are expected to generate some 10 petabytes (10 million gigabytes or more than 2 million DVDs) of data, data that about 10,000 physicists from around the globe will want to analyze.

"It presents an unprecedented scientific computing challenge," said Neubauer, who likened the situation to a Thanksgiving meal in which family members sit around the table salivating over the food. As a fellow with the UI's National Center for Supercomputing Applications, Neubauer will tackle those computing challenges.

He's also leading the Illinois effort to get the system ready for first proton collisions later this year and to develop new electronics that will allow the detector to make what are called "triggering" decisions.

Because scientists will have the ability to collide all those bunches of 100 billion protons at 40 million times a second, there's a whole lot of collisions to study. What triggering does is use an algorithm to sift through those billion events in order to select the most interesting ones, Neubauer said.

"We have learned a great deal from running the Tevatron at Fermilab," Liss said. And now with the Large Hadron Collider set to go online, he said he is hopeful "we will be able to make new inroads in our understanding" about the nature of the universe and the fundamental forces of nature.