What We’ll Find Inside The Atom

To appreciate why gravity is such a bear requires going a bit further into the labyrinth. According to quantum theory, the force between two objects (either an attraction or a repulsion) requires an exchange of a "force-carrying" particle. Imagine two ice skaters playing catch. When Joe throws the baseball, he recoils from Moe. When Moe catches the ball, he recoils from Joe. It works in a similar way for attraction. Imagine our two skaters facing away from each other, toward separate walls. Joe throws a soft, bouncy ball hard and high toward his wall. It bounces over to Moe's wall and into Moe's glove. Look! They are now drawing together!

The ball—the force-carrying particle—is called a boson, and there's a different one for each type of force. Experimenters working with small colliders have revealed the presence of the bosons that carry the strong force between quarks, electrically charged particles and the weak force. However, the force carrier of gravity—a particle called a graviton—is completely different. Particle accelerators are useless here because the gravitational force is fantastically weak. Do this test: Drop a paper clip. It falls, being attracted by the entire planet. Now, hold the paper clip using the magnet that keeps your shopping list onto the fridge. The pull of the entire Earth fails; the little magnet wins. When the force of gravity is tested carefully against the electrical force, it is found to be weaker by a factor of one followed by 40 zeros.

Is the LHC powerful enough to produce a graviton? No. That would require a much bigger collider. Nevertheless, we do have some hope that the LHC will add to our understanding of Einstein's gravity. It will have to be done indirectly, however. We'll have to look at many other phenomena and make inferences about gravity.

What is the God particle? One of the paths to seeing into the cosmic kaleidoscope would be to observe a particular type of boson called the Higgs. A boson, remember, is a particle associated with a force. The Higgs boson accounts for the mass of other particles. Think of the Higgs as a field of mud. When you walk through it, you move more slowly, as if you had put on weight. By the same token, the presence of a Higgs boson would make a particle heavier. For reasons that are too elaborate to go into here, the Higgs is within the realm of the LHC—it is absolutely possible that we will discover it soon. And finding it would unlock many mysteries. That's why some people like to call it the God particle.

Ask a physicist why it was necessary to build the LHC, and the answer is unvarying: "Higgs!" Talk about the Higgs has been around for decades. Its power to turn the heads of experimentalists, as well as leaders from the United States, Europe and Japan, is impressive. It heads the list of motivations for building expensive particle accelerators.

Here's why: the Higgs could be the cause of the complexity of our array of particles and forces. Call it the Higgs field (think mud), and let's say it pervades all of space. Without a Higgs field, quarks and leptons and all other particles would all have zero mass. The four forces would simplify to one, the array of quarks and leptons would coalesce, and theoretical physicists would turn to the employment ads. With a Higgs field in the picture, particles tramp through mud: the electrons acquire a bit of mass, the muons get more, the beauty quark gets really heavy and the top quark gets obese. Particles called Ws and Zs acquire large masses, whereas the photon simply ignores the Higgs field. But now the mathematics becomes complex, the four forces re-emerge—and there is full employment for theorists.