One particularly auspicious day about 14 billion years ago…it could have been a Tuesday…the universe began. In a fiery maelstrom that we now call the Big Bang, matter as we know it didn't exist. Instead, the universe was pure energy, with evanescent subatomic particles flickering in and out of existence. This era of energy didn't last long. In a fraction of a second, the universe cooled and the particles that make up our familiar cosmos came into being. Never again would the universe commonly see this kind of phenomena.
Well, until now.
On March 30, 2010, an enormous particle accelerator or "atom smasher" called the Large Hadron Collider (LHC) ramped up to full operations. Just outside Geneva, Switzerland, in an underground laboratory called the CERN European Organization for Nuclear Research, scientists are using the LHC to try to recreate the conditions that existed at the time of the Big Bang. They want to gain a better understanding of the building blocks of our universe and to figure out how they came to be; they want to probe the very moment of creation.
For its potential to investigate unknown parts of the universe, the LHC has been called "the Hubble telescope of inner space." It's one of the most audacious endeavors in modern science, with an eight billion dollar price tag (mostly funded by European taxpayers) and a workforce consisting of thousands of international scientists and researchers—including University of Iowa faculty, staff, and students.
The UI's contribution begins with four faculty members—Usha Mallik, Jane Nachtman, 91BS, Charles Newsom, and Yasar Onel—from the physics department in the College of Liberal Arts and Sciences. A coterie of postdoctoral researchers, graduate students, engineers, and technicians, most of them funded by large grants from the U.S. Department of Energy, also represent the Hawkeye state at the LHC. Some research is actually carried out on campus, but the UI teams also travel regularly to Europe to help conduct and analyze the results of experiments.
While many laboratories in America and elsewhere conduct research into subatomic particles, the LHC represents the future of this kind of endeavor. Iowa's affiliation with the lab began in 1993, when Onel joined one of its research teams. Those were dark times for particle physics in the U.S. For a variety of political and budgetary reasons, Congress had just cancelled the Superconducting Supercollider, the United States' planned next-generation particle accelerator, on which Iowa had been a collaborating institution. It was natural for the Iowa group to turn its attention to the LHC, although at that time the project was little more than a dream for scientists who wanted to study the fundamental matter of our universe.
Matter is made of atoms, which consist of little particles called protons, neutrons, and electrons. In turn, protons and neutrons are made of even smaller particles called quarks. Quarks and leptons (the most familiar of which is the electron) are the basic building blocks of the universe and everything—from ants to planets—in it.
To investigate these infinitesimal particles, scientists had to build the world's largest machine (and the most expensive scientific experiment in history). The LHC even has its own supercomputer—a networked grid of tens of thousands of computers around the world—to store and share the mountains of data from its experiments.
"This is the most complex machine ever built, and it is a constant fight to get everything working at once," says UI physics professor Charles Newsom. "We've been slowly weeding out the zillions of expected and unexpected problems in getting such a complex detector and machine synergy going. More often than not, we scratch our heads wondering why things failed the last time. But, we always overcome and then we can move forward. It's a real 'three steps forward, two steps back' situation. But, it's very gratifying when everything works—and part of the reason why we are willing to put in so many years of effort."
The accelerator fills 18 miles of tunnels. It includes enormous particle detectors that lurk in underground caverns, miles of tubes and wiring, 9,000 magnets, and thousands of other pieces of sophisticated equipment all connected to a control center. In operation, the LHC acts much like a giant pinball machine. It sends two beams of protons racing in different directions at almost the speed of light around a ring of super-cooled magnets. Ultimately, the beams collide inside the narrow tunnels with a mind-boggling amount of energy—some seven trillion electron volts, which is three-and-a-half times higher than ever before accomplished by humankind.
The collisions take place and are monitored inside four particle detectors, two of which conduct the largest experiments and are the research homes of the Iowa contingent. Mallik leads a team on the five-story ATLAS (A Toroidal Large ApparatuS), while Nachtman, Newsom, and Onel work on the slightly smaller CMS (Compact Muon Solenoid). While these detectors look for the same things, they use different engineering methods to approach the task of discovering the unexpected and taking precise measurements.
At the heart of these gigantic machines lie millions of tiny pixel detectors—silicone dots about the size of the period at the end of this sentence. When proton beams pass through each other, these dots capture valuable data about the complicated mix of collisions—up to almost a billion per second once the LHC is operating at full capacity.
Physicists then link the dots to determine the particles' trajectories. In many ways, it's like trying to put together a child's "connect-the-dots" picture, although the huge number of dots makes it necessary to employ banks of computers and the most complex algorithms to pull it off.
Why are scientists so keen to dissect the antics of these miniscule particles? Because they could hold the key to some of the universe's greatest mysteries. For all of science's successes in understanding matter, which physicists have formalized in a collection of ideas called "The Standard Model," some troubling anomalies persist. Why, for instance, are there only two kinds of matter particles: quarks and leptons? Why not more? And why do they have different masses?
The answer to that last question may start with the Higgs energy field. A theory postulated in 1964 proposes that subatomic particles move differently through this field, which permeates everything in the universe. Heavy quarks interact with it strongly, while very light leptons barely at all. These interactions give particles their mass.
Of course, all this is speculation, because the Higgs field hasn't actually been discovered. Iowa researchers are hot on its trail, though. If the theory is correct, it predicts a particle called the Higgs boson, which could be found in the LHC. To the general annoyance of scientists, the Higgs boson is widely but rather simplistically and sensationally known as "the God Particle" after a popular book called The God Particle: If the Universe Is the Answer, What is the Question?
Meanwhile, other UI researchers are analyzing LHC data in an attempt to find proof of theoretical "cousin particles." These relate to the theory of supersymmetry, which states that every particle in the universe is matched by a cousin particle. Subatomic particles can (with some poetic license) be thought of as little spinning balls, and cousin particles differ from their regular counterparts in the way they spin.
Discovering the existence of cousin particles could help solve the enduring puzzle of why gravity is so weak. Although gravity keeps planets in orbit and controls the oceans' tides, its influence is puny compared to the other three fundamental forces of nature: electromagnetism, weak nuclear force, and strong nuclear force. Take the simple example of a paperclip dangling from a small magnet. The magnet holds the paperclip hostage, despite the fact that gravity from the entire Earth attempts to pull it down.
At the European atom smasher, answers to such questions are a tantalizing prospect. And, of course, there's always the possibility of surprises. This fall, the CMS experiment observed what some physicists have interpreted as a type of matter not common in the universe since the very beginning of time. Over the next few years and in more complex studies, physicists will wade through a deluge of measurements to verify existing theories about physical phenomena and then to push forward into the unknown.
"The LHC will yield a veritable gold mine of data, with the Higgs field and supersymmetry being the most thrilling initial topics," says Mallik. "However, we are all prepared for the unexpected to show up, which in many ways will be even more exciting."
Exciting for physicists, anyway. After all, most people struggle to get beyond the basics of such complex topics. Then there's the issue of whether such research—phenomenally expensive but often short on results—is even valuable. While such scientific endeavor has spawned spinoffs from cancer therapies to the World Wide Web (which was invented at the CERN laboratory), particle physics research—whether on the UI campus, at the LHC, or at other laboratories around the world—isn't driven by such practical motivations. Instead, it's the latest chapter in the ongoing saga that began when the first human stared at the sky and wondered what the universe is all about and how it began.
Perhaps the best answer to "Why conduct particle physics research?" came from Robert Wilson, former director of the U.S Department of Energy's Fermilab national laboratory, which, like the LHC, specializes in high-energy particle physics. When asked by a U.S. senator how the Illinois lab would be used and whether it might contribute to national defense, Wilson responded unexpectedly. Although he was referring to Fermilab, his remarks also illuminate the significance of the work being carried out at the LHC.
LHC. "It has only to do with the respect with which we regard one another, the dignity of men, our love of culture," he said. "It has to do with 'Are we good painters, good sculptors, great poets?'—all the things we really venerate and honor…. It has nothing to do directly with defending [a] country— except to make it worth defending."
Discoveries of enormous scientific importance are often called groundbreaking or earth-shattering. With the Large Hadron Collider, some people feared that would be the literal truth.
In 2008, as scientists began preparing for operations at the LHC, international media ran headlines about Armageddon and doomsday machines. Some concerned citizens and scientists even filed lawsuits in several courts, including the European Court of Human Rights, claiming that the CERN laboratory, home to the LHC, should be shut down before it unleashed a black hole that would destroy the world.
An electrical mishap—albeit a simple industrial accident and nothing dangerous— that put the LHC offline after just eight days of operation, rendering it out of commission until this year, didn't exactly reassure skeptics and naysayers.
Nonetheless, CERN published its own in-depth safety reviews, while leading scientific organizations, including the American Physical Society, confirmed that the experiment to recreate conditions around the time of the Big Bang posed no threat to humankind. Renowned theoretical physicist Stephen Hawking said, "The world will not come to an end when the LHC turns on. The LHC is absolutely safe.... Collisions releasing greater energy occur in the Earth's atmosphere and nothing terrible happens."
Indeed, the LHC has run without incident since March. Although it's billed as the "highest energy particle accelerator in the world," that term is relative. The collision between two particular protons involves about as much energy as a mosquito zooming in on a target. Even the cumulative energy of all the particles in the beam is comparable only to a commuter train moving at top speed. Where the LHC sets records is in energy concentration, as the energy from particle collisions is focused into a region much smaller than the nucleus of an atom.
As far as scientists are concerned, the LHC is far from dangerous; it's a triumph of human ingenuity and endeavor.
Accelerator Laboratory and an adjunct professor at the University of Notre Dame. He is author of two books about particle physics for the public, including the recently released The Quantum Frontier: The Large Hadron Collider.