The Big Bang Is Back: page 2
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."
