The world's largest and most powerful particle accelerator will begin operations later this year at CERN, the European Organization for Nuclear Research. Scientists believe the new atom-smasher, known as the or LHC for short, will help them answer questions about the origin of the universe. The collider is 27 kilometers in circumference, straddling the French-Swiss border near Geneva, buried as deep as 150 meters underground.
A group of visitors, wearing fire-engine red helmets, takes an elevator deep underground. From there, the group follows project leader Peter Jenni up creaky stairs to dizzying heights. Engineers and technicians are installing a massive detector, about the height of a six-story building. Jenni explains how it works.
"You see this tube coming out. That is the connection to the tunnel. The beam pipe...goes through this hole in the middle of this device which you see there, and then the particles will collide in the center of this detector of this barrel cylinder, which is 26 meters long."
When it is completed, the LHC will accelerate two beams of protons in opposite directions around a circular track. Jenni says the protons will move at nearly the speed of light. "40 million times a second, two bunches cross. So it's boom, boom, boom, boom - 40 million times a second."
The beams that are injected into the LHC will travel through a vacuum guided by superconducting magnets operating at extremely cold temperatures near absolute zero. Each beam will consist of nearly 3,000 bunches, with each bunch containing as many as 100 billion particles. When head-on collisions occur, they will produce a shower of new particles. But the most interesting new particles will be very rare events.
There are four major experiments. The two biggest ones, code-named Atlas and CMS, are general-purpose experiments. The others, Alice and LHCb, are smaller and more specialized. But all, in different ways, will seek to reveal nature's secrets.
Through the collisions, scientists aim to recreate the conditions that existed at the time of the Big Bang, when the universe was born. French physicist Yves Schutz works at the Alice Experiment. He says everything happened in the Big Bang.
"The universe and whatever is in the universe have been created in the Big Bang," he says. "So there are several approaches. One is to find what were all these particles which do not exist today anymore, but which existed at the origin and which contributed to the creation of the universe. What Alice is trying to do is to recreate the environment in which the universe was, and to study what was the nature of matter at this early time of our universe."
CERN has been working on the $8 billion LHC for about two decades. More than 10,000 scientists and engineers from some 60 countries are involved in the project. Equipment is being built in many European countries, as well as places such as Canada, Japan, Russia and the United States, which has contributed half a billion dollars to the project. Even political rivals China and Taiwan, and India and Pakistan, find scientific common ground collaborating with each other on the Large Hadron Collider.
Physicists believe the LHC will uncover a long-sought new [subatomic] particle called the Higgs boson. Spokesman for the CMS experiment, Jim Virdee, says it could hold the answer to why sub-atomic particles have weight or mass.
"Our goal is that we have to build a unified theory of physics," he says. "That means there is a single theory, which explains all physical phenomena that we observe in our universe, all of them. Gravity you are very familiar with. Electromagnetism you are very familiar with."
Virdee says when the Big Bang occurred "you could not tell the difference between gravity and electromagnetism," because they behaved in the same way. Today, he says, "They have very different behavior."
The LHC is set to start operations in November. But physics results are not expected before the machine gets up to speed in early summer of 2008.
The LHC is expected to produce frontier physics for about 10 years. But scientists already are discussing the next generation of accelerator to be built. The scientific community generally agrees the LHC's successor will be a giant linear electron-positron collider, about 30 kilometers in length. Competition among CERN, the United States and Japan to win the rights to build the machine is intense.