What We’ll Find Inside The Atom

The Higgs is key to unraveling the "mirror system" in our kaleidoscope example. Higgs also cures some mathematical pathology. Vigorous but fruitless searches for the Higgs were made at the major accelerators, but definitive evidence for Higgs phenomena will almost surely emerge from early LHC research.

How does a collider help solve these mysteries? The LHC is built to cause collisions between particles, and then give physicists a view of the resulting debris. Particles, as we know from quantum theory, are associated with force fields, which means if you find a particle (like the Higgs boson) you've also found the associated force field (the Higgs field). If the energy level of the collider is high enough—and the LHC is the highest yet—its collisions will produce more massive particles. That raises the odds that out of the millions of collisions produced each second, the LHC will produce a Higgs boson. These will then be picked up by detectors hooked to powerful computers, to thunderous applause in the control room. If this happens 10 or 20 times, it will quickly lead to worldwide rejoicing! This is how all the particles we know about—the quarks and leptons and bosons—were discovered in older particle accelerators. What makes the LHC a big deal is that its energy is high enough to produce the Higgs boson.

The quest for unification, however, doesn't end with the Higgs. One of the telltale signs of a unifying "theory of everything" would be something called supersymmetry. This is a mathematical theory suggesting that all the known particles—quarks and leptons—must have twins. None of these twins have been discovered (but that hasn't stopped us from giving them poetic names: squarks, sleptons). The LHC, however, could change that.

Let's go back to that point in time 13.7 billion years ago, when all of space and its contents occupied almost zero volume. Ever since then, the universe has been expanding; all galaxies are moving away from one another. But gravity is attractive, pulling the galaxies closer together, which should slow down the expansion. In 1998, two groups of experimenters tried to measure the rate at which the expansion of the universe was slowing, but their answer came as a shock: the expansion was not slowing; it was accelerating! Something, therefore, must be acting mysteriously to push all matter outward. We call this dark energy. Dark energy is probably one of the most baffling but most important discoveries about our universe. When we calculate the amount of energy required to push all galaxies away from each other, the figure is massive: it accounts for about 75 percent of all the energy in the universe.

How can the LHC help find dark energy? Dark energy has a greater virtue than merely baffling theoretical astrophysicists. Dark energy adds to the total amount of energy in the universe, which compensates for the curvature caused by matter. (Einstein told us that matter causes space to curve, but if energy and matter are balanced, there's no curvature—and the universe is flat.) But like some kinds of energy, dark energy may possibly have a particle associated with it—a "dark energy particle." Because the LHC is designed to look for particles, it could conceivably find a dark energy particle (if it exists).

There's another unsolved mystery about the motion of the galaxies and stars within galaxies. When astronomers calculate how galaxies and stars should move according to the laws of gravity, they find that the equations give them a wrong answer. Observations show that stars and galaxies behave as though there is much more matter in the galaxy than can be deduced by counting stars (estimating by experience the mass of each star and adding them all up). To understand the stability of the stars in a galaxy, one must assume over ten times more matter than is observed. What could be causing this discrepancy? The conclusion is that galaxies are surrounded by clouds of matter that exert gravitational forces but which do not shine—so we call it dark matter.