[Editor’s note: Everything in the following article, which will be presented in three parts, is true.]
In a few weeks, researchers at the Brookhaven National Laboratory will culminate 17 years of planning and construction and collide two beams of accelerated and highly energetic gold ions in order to probe the frontiers of physics. It will be the first experiment at Brookhaven’s newest facility, the Relativistic Heavy Ion Collider (RHIC or “Rick” for short), a long-awaited particle accelerator that will be capable of shooting bigger particles at greater energies than any of its predecessors. Within these fiery collisions, scientists hope to produce an elusive substance known as “quark-gluon plasma,” a sort of ur-matter that physicists think probably existed in the first milliseconds after the Big Bang. Observing quark-gluon plasma would tell us about the nature of matter and the birth of the universe—big news in science circles.
The trouble is, the experiment could also be the end of the world. RHIC is at the cutting-edge of a branch of physics that is still heavily theoretical and not entirely understood, and there has been speculation that the immense energy generated in RHIC’s collisions could cause any one of several cosmic disasters, which, depending on the disaster, would destroy either the Earth or the entire universe.
RHIC’s potentially cataclysmic side effects began appearing in the press last summer. An exchange of letters in the July 1999 issue of Scientific American addressed the issue, and the July 18 edition of London’s Sunday Times featured a story with the headline “Big Bang machine could destroy the earth,” and editorialized against RHIC. Brookhaven reacted quickly, issuing a response to these specific articles and commissioning a panel of scientists to consider any dangers associated with the upcoming experiments. The resulting Review of Speculative Disaster Scenarios concluded that the probability of something going wrong is “firmly excluded by existing empirical evidence, compelling theoretical arguments, or both.” Although its authors see “no reason to delay the commissioning of RHIC,” and the rest of the scientific community agrees, it is hard to undo fears of the end of the world. Brookhaven scientists have received hundreds of letters and emails expressing concern. And Walter Wagner, whose letter to Scientific American in July helped touch off the controversy, even filed a lawsuit seeking an injunction against Brookhaven initiating the experiment. (His case was since thrown out of a New York court.)
The fuss over RHIC is not unprecedented. Brookhaven has a checkered past of environmental problems (it was designated a superfund site a few years ago), and any new project there is bound to face some scrutiny. Beyond the environmental issues—and destroying the world is no doubt an environmental issue—fears about RHIC reflect something deeper: our long-standing fundamental suspicion of the scientific endeavor. It is an ever-present theme in our myths and literature, from the Fall from Grace, to Prometheus, to Dr. Strangelove. This is why all new scientific developments are greeted with some anxiety about their unintended consequences. Knowledge of atoms advanced our understanding of the world and radically improved our technological capabilities, but it also made nuclear weapons possible. Genetic engineering will help us fight disease and hunger around the world, but it also carries the threat of biological destruction. And now, the reasoning goes, scientists at Brookhaven might up the Faustian ante by tinkering with our cosmic origins at the cost of disrupting the fabric of the universe. RHIC is the latest station along a trajectory of epistemological fear: if the search for knowledge means trouble, RHIC might mean big trouble.
Brookhaven National Laboratory occupies over 5,000 acres of inland Long Island, about three-quarters of the way towards the eastern tip, and one-and-a-half hours east of New York City by car. Just below the sandy pines and preserved wetlands that surround Brookhaven and the nearby small town of Upton, RHIC is awhirr with activity. Construction was completed six months ago, but bringing RHIC online is taking longer than expected. As Achim Franz, a project coordinator for PHENIX, one of the four sensing instruments stationed along RHIC’s ring, explains, “This is a brand new machine, and it’s very sensitive, so it takes time to understand it and make it work.” After some last-minute adjustments, the ring has been sealed, and RHIC’s massive refrigerators are humming along, cooling the liquid helium that bathes the magnets to 4 degrees above absolute zero (around minus 450 degrees Fahrenheit).
Once ready, RHIC’s 2.4 mile, slightly oval course—a twin set of magnetic rings wrapped in 1,600 miles of braided niobium-titanium—will begin separating gold atoms from their electrons, accelerating the resulting ions to 99.995 percent of the speed of light, and then crashing them into each other in violent collisions that will reach temperatures 10,000 times hotter than the core temperature of the sun. “The total energy when the ions meet will be 40 [trillion] electron volts,” explains Franz. “In our world this is the energy released in a collision between two mosquitoes. But on a sub-atomic scale, that’s a huge amount of energy.” For decades, scientists have known that ordinary matter—the protons and neutrons we are familiar with from high school science—is actually made up of smaller sub-atomic particles called quarks, held together by gluons. But theory suggests that just after the Big Bang, when the quickly inflating fireball of the universe was still hotter than one trillion degrees, quarks and gluons floated freely. By the end of time’s first second, the universe had cooled enough for quarks to start forming protons and neutrons, which then clung together as atoms—and the rest, as they say, is history.
At RHIC, the intense energy of the gold ion collisions will recreate the extraordinary conditions of that first second. Tim Hallman, the Group Leader of STAR, the second-largest detection instrument along the ring, hopes it will create enough energy “to compress the protons and neutrons in the gold nuclei together to such an extent that they lose their identity and the quarks and gluons inside become, for a brief moment, what we call ‘deconfined’”—that is to say, they will return to their beginnings and melt back into quark-gluon plasma.
The quark-gluon plasma of the Big Bang lasted a few millionths of a second, but the replicate version will live an even shorter life: perhaps a hundred trillionths of a trillionth of a second. Still, this is enough time for RHIC’s experimental devices—PHENIX, STAR, and their junior partners, PHOBOS and BRAHMS—to collect a great deal of data—information that may help advance our understanding of the universe. Hallman sees RHIC as the next step in the progression of physics: “We are essentially answering a fundamental question that man has asked before: what is the nature of matter? One of the ways to find out is by heating it; if you have some matter, and you heat it, how does the matter change?”
A hundred years ago, scientists did similar experiments, only with less energy and at lower temperatures, and the results gave birth to quantum mechanics. Similarly, RHIC might open unknown vistas of new physics. Hallman is enthusiastic about the possibility of discovery. “Now,” he says, “we can use much higher temperatures. And it’s exciting to take that next step, because you don’t have these kinds of opportunities for big advances very often.”
But will that step be our last?
[continued tomorrow]