The Big Bang Is Back

This is probably not the way the world ends: sometime this fall, researchers at Brookhaven National Laboratory will tap a few commands into a computer terminal, bringing their new particle accelerator--the Relativistic Heavy Ion Collider, or RHIC--up to full power. Atoms of gold--heavy enough to cause some real quantum fireworks--will course around two nearly circular, 2.4-mile "racetracks" in opposite directions at 99.9 percent of the speed of light. The nuclei will smash into each other, exploding at a temperature 10,000 times hotter than at the center of the sun. For a hundred trillionths of a trillionth of a second, conditions will mirror the universe immediately after the big bang. From that brief genesis, though, a new universe will not be born. It won't grow, and it won't destroy the pre-existing universe, one we know and love. No Apocalypse, no Big Goodbye.

So don't panic. Brookhaven physicists really are shaking down RHIC. And while they checked to make sure they weren't going to bring about the End Time in the process, they are going to be playing with some seriously primal forces. The $365 million collider will accelerate heavier ions--charged atomic particles--at higher energies than anywhere else in the world. If all goes well, RHIC will indeed simulate the universe right after the big bang and create a state of matter unseen on Earth, testing basic theories about what the universe is made of and how it got that way. "It's like a tiny peephole into the whole way cosmology works," says Miklos Gyulassy, a physicist at Columbia University. "We're trying to re-create the birth of the universe in a laboratory."

Under construction since 1991, RHIC is the largest accelerator at Brookhaven, on New York's Long Island. Other accelerators, like those at CERN in Switzerland or Fermilab in Illinois, generally shoot particles called protons. RHIC heaves complete nuclei, anything from a hydrogen nucleus--one proton--to a gold nucleus, a massive 79 protons and 118 neutrons. It does it at astounding energies--each particle in a gold nucleus has an energy measuring 100 billion electron-volts. RHIC accelerates them with a series of electrical fields into head-on collisions registering 40 trillion electron-volts.

At these energies, going nearly the speed of light, some pretty weird stuff happens. For ions traveling at these relativistic speeds, time moves more slowly. The particles don't notice collisions right away; instead, they pass through each other and blow up an instant later. Albert Einstein pointed out that energy and mass are interchangeable, and indeed the energy of collision gets transmuted into tens of thousands of subatomic particles. This much energy is like turning up the heat to 10 trillion degrees Kelvin. At that temperature, "we expect to create this new state of matter where there's a basic restructuring," says Tim Hallman, a physicist working on RHIC. "The fundamental particles inside other particles are actually free to come out."

If that happens, researchers will see a kind of matter never seen on Earth, an ultrahot, ultradense soup called a quark-gluon plasma. Quarks are the basic particles that combine to form protons and neutrons; gluons are the particles that hold them together. Smashed against each other hard enough, protons and neutrons can undergo a "phase transition," turning into quark-gluon plasma like water vaporizing into steam. These plasmas live fast and die young, so RHIC has four detectors, each designed to look for different signs of its passing. For example, the transition should kick off certain particles at specific ratios, trajectories and speeds--all of which the detectors pick up. They'll also measure temperature, because theory says it should hold steady while the transition is in progress.

Emotions surrounding the collider, on the other hand, are heating up. Last month The Sunday Times of London ran an article headlined big bang machine could destroy earth. After seeing the article, another reporter called Brookhaven to ask whether it had created a black hole that destroyed John F. Kennedy Jr.'s plane. Larry McLerran, who takes over Brookhaven's nuclear-theory group in September, explains that some physicists--not him--thought the collider could create a region of space where matter had a different mixture of quarks than in our world, which "would begin expanding and eat up the universe we live in." Or a collision could give rise to particles containing a type of quark called "strange," which would convert everything around them to more "strangelets" (and obliterate our nonstrangelet universe). But, say the physicists, the world won't end with this particular bang. "These collisions have been going on since the beginning of time," says McLerran. "There are nuclei in cosmic rays, and they collide with one another at very high densities. And we're still alive."

Why do the research at all? While quantum theory predicts the existence of quark-gluon plasma, it doesn't detail its every characteristic--no one even knows what temperature creates it. And RHIC-size collisions also mimic the conditions in the depths of neutron stars and exploding supernovas, providing astrophysics in a bottle. Running protons through the collider may eventually solve the mystery of what causes them to "spin" in the particular way they do. But history may provide an even better reason. Around the turn of the century, physicists were chasing another temperature frontier, this one at about 10,000 degrees K. When they hit it, the data they got were totally unexpected. In trying to figure out what happened, a physicist named Max Planck figured out that energy came in discrete packets--what he called quanta. It was the birth of quantum physics: the basics of how matter and energy work. "The knowledge that came out of that is the basis for our entire modern life," says Hallman. "We fully expect that our data will match the theory... on the other hand, in 1900 they fully expected their data would match the theory, too." Let's just hope he's right about that destruction-of-the-universe thing.