Time isn't the only quantity that ranges from the unimaginably infinitesimal to the endless. The smallest distance that is relevant to measurement today is something like 10−17 centimeters, which is how far a thing called the Z0 (zee zero) can travel before it departs our world. Theorists sometimes deal in much smaller space concepts; for instance, when they talk about superstrings, a trendy but very abstract and very hypothetical theory of particles, they say that the size of a superstring is 10−35 centimeters, real small. At the other extreme, the largest distance is the radius of the observable universe, somewhat under 1028 centimeters.
A TALE OF TWO PARTICLES AND THE ULTIMATE T-SHIRT
When I was ten years old, I came down with the measles, and to cheer me up my father bought me a book with big print called The Story of Relativity, by Albert Einstein and Leopold Infeld. I'll never forget the beginning of Einstein and Infeld's book. It talked about detective stories, about how every detective story has a mystery, clues, and a detective. The detective tries to solve the mystery by using the clues.
There are essentially two mysteries to be solved in the following story. Both manifest themselves as particles. The first is the long-sought a-tom, the invisible, indivisible particle of matter first postulated by Democritus. The a-tom lies at the heart of the basic questions of particle physics.
We've struggled to solve this first mystery for 2,500 years. It has thousands of clues, each uncovered with painstaking labor. In the first few chapters, we'll see how our predecessors have attempted to put the puzzle together. You'll be surprised to see how many "modern" ideas were embraced in the sixteenth and seventeenth centuries, and even centuries before Christ. By the end, we'll be back to the present and chasing a second, perhaps even greater mystery, one represented by the particle that I believe orchestrates the cosmic symphony. And you will see through the course of the book the natural kinship between a sixteenth-century mathematician dropping weights from a tower in Pisa and a present-day particle physicist freezing his fingers off in a hut on the cold, wind-swept prairie of Illinois as he checks the data flowing in from a half-billion-dollar accelerator buried beneath the frozen ground. Both asked the same questions. What is the basic structure of matter? How does the universe work?
When I was growing up in the Bronx, I used to watch my older brother playing with chemicals for hours. He was a whiz. I'd do all the chores in the house so he'd let me watch his experiments. Today he's in the novelty business. He sells things like whoopee cushions, booster license plates, and T-shirts with catchy sayings. These allow people to sum up their world view in a statement no wider than their chest. Science should have no less lofty a goal. My ambition is to live to see all of physics reduced to a formula so elegant and simple that it will fit easily on the front of a T-shirt.
Significant progress has been made through the centuries in the search for the ultimate T-shirt. Newton, for example, came up with gravity, a force that explains an amazing range of disparate phenomena: the tides, the fall of an apple, the orbits of the planets, and the clustering of galaxies. The Newton T-shirt reads F = ma. Later, Michael Faraday and James Clerk Maxwell unraveled the mystery of the electromagnetic spectrum. Electricity, magnetism, sunlight, radio waves, and x-rays, they found, are all manifestations of the same force. Any good campus bookstore will sell you a T-shirt with Maxwell's equations on it.
Today, many particles later, we have the standard model, which reduces all of reality to a dozen or so particles and four forces. The standard model represents all the data that have come out of all the accelerators since the Leaning Tower of Pisa. It organizes particles called quarks and leptons—six of each—into an elegant tabular array. One can diagram the entire standard model on a T-shirt, albeit a busy one. It's a hard-won simplicity, generated by an army of physicists who have traveled the same road. However, the standard-model T-shirt cheats. With its twelve particles and four forces, it is remarkably accurate. But it is also incomplete and, in fact, internally inconsistent. To have room on the T-shirt to make succinct excuses for the inconsistencies would require an X-tra large, and we'd still run out of shirt.
What, or who, is standing in our way, obstructing our search for the perfect T-shirt? This brings us back to our second mystery. Before we can complete the task begun by the ancient Greeks, we must consider the possibility that our quarry is laying false clues to confuse us. Sometimes, like a spy in a John le Carré novel, the experimenter must set a trap. He must force the culprit to expose himself.
THE MYSTERIOUS MR. HIGGS
Particle physicists are currently setting just such a trap. We're building a tunnel fifty-four miles in circumference that will contain the twin beam tubes of the Superconducting Super Collider, in which we hope to trap our villain.
And what a villain! The biggest of all time! There is, we believe, a wraithlike presence throughout the universe that is keeping us from understanding the true nature of matter. It's as if something, or someone, wants to prevent us from attaining the ultimate knowledge.
This invisible barrier that keeps us from knowing the truth is called the Higgs field. Its icy tentacles reach into every corner of the universe, and its scientific and philosophical implications raise large goose bumps on the skin of a physicist. The Higgs field works its black magic through—what else?—a particle. This particle goes by the name of the Higgs boson. The Higgs boson is a primary reason for building the Super Collider. Only the SSC will have the energy necessary to produce and detect the Higgs boson, or so we believe. This boson is so central to the state of physics today, so crucial to our final understanding of the structure of matter, yet so elusive, that I have given it a nickname: the God Particle. Why God Particle? Two reasons. One, the publisher wouldn't let us call it the Goddamn Particle, though that might be a more appropriate title, given its villainous nature and the expense it is causing. And two, there is a connection, of sorts, to another book, a much older one...
THE TOWER AND THE ACCELERATOR
And the whole earth was of one language, and of one speech.
And it came to pass, as they journeyed from the east, that they found a plain in the land of Shinar; and they dwelt there. And they said one to another, Go to, let us make brick, and burn them thoroughly. And they had brick for stone, and slime had they for mortar. And they said, Go to, let us build us a city and a tower, whose top may reach unto heaven; and let us make us a name, lest we be scattered abroad upon the face of the whole earth.
And the Lord came down to see the city and the tower, which the children of men builded. And the Lord said, Behold, the people is one, and they have all one language; and this they begin to do: and now nothing will be restrained from them, which they have imagined to do. Go to, let us go down, and there confound their language, that they may not understand one another's speech.
So the Lord scattered them abroad from thence upon the face of all the earth: and they left off to build the city. Therefore is the name of it called Babel.
—Genesis 11:1–9
At one time, many millennia ago, long before those words were written, nature spoke but one language. Everywhere matter was the same—beautiful in its elegant, incandescent symmetry. But through the eons, it has been transformed, scattered throughout the universe in many forms, confounding those of us who live on this ordinary planet orbiting a mediocre star.
There have been times in mankind's quest for a rational understanding of the world when progress was rapid, breakthroughs abounded, and scientists were full of optimism. At other times utter confusion reigned. Frequently the most confused periods, times of intellectual crisis and total incomprehension, were themselves harbingers of the illuminating breakthroughs to come.
In the past few decades in particle physics, we have been in a period of such curious intellectual stress that the parable of the Tower of Babel seems appropriate. Particle physicists have been using their giant accelerators to dissect the parts and processes of the universe. The quest has, in recent years, been aided by
astronomers and astrophysicists, who figuratively peer into giant telescopes to scan the heavens for residue sparks and ashes of a cataclysmic explosion that they are convinced took place 15 billion years ago, which they call the Big Bang.
Both groups have been progressing toward a simple, coherent, all-encompassing model that will explain everything: the structure of matter and energy, the behavior of forces in environments that range from the earliest moments of the infant universe with its exorbitant temperature and density to the relatively cold and empty world we know today. We were proceeding nicely, perhaps too nicely, when we stumbled upon an oddity, a seemingly adversarial force afoot in the universe. Something that seems to pop out of the all-pervading space in which our planets, stars, and galaxies are embedded. Something we cannot yet detect and which, one might say, has been put there to test and confuse us. Were we getting too close? Is there a nervous Grand Wizard of Oz who sloppily modifies the archaeological record?
The issue is whether physicists will be confounded by this puzzle or whether, in contrast to the unhappy Babylonians, we will continue to build the tower and, as Einstein put it, "know the mind of God."
And the whole universe was of many languages, and of many speeches.
And it came to pass, as they journeyed from the east, that they found a plain in the land of Waxahachie, and they dwelt there. And they said to one another Go to, let us build a Giant Collider, whose collisions may reach back to the beginning of time. And they had superconducting magnets for bending, and protons had they for smashing.
And the Lord came down to see the accelerator which the children of men builded. And the Lord said, Behold the people are un-confounding my confounding. And the Lord sighed and said, Go to, let us go down, and there give them the God Particle so that they may see how beautiful is the universe I have made.
—The Very New Testament, 11:1
2. THE FIRST PARTICLE PHYSICIST
He seemed surprised. "You found a knife that can cut off an atom?" he said. "In this town?"
I nodded. "We're sitting on the main nerve right now," I said.
—With apologies to Hunter S. Thompson
ANYONE CAN DRIVE (or walk or bicycle) into Fermilab, even though it is the most sophisticated scientific laboratory in the world. Most federal facilities are militant about preserving their privacy. But Fermilab is in the business of uncovering secrets, not keeping them. During the radical 1960s the Atomic Energy Commission told Robert R. Wilson, my predecessor and the lab's founding director to devise a plan for handling student activists should they arrive at the gates of Fermilab. Wilson's plan was simple. He told the AEC he would greet the protesters alone, armed with a single weapon: a physics lecture. This was lethal enough, he assured the commission, to disperse even the bravest rabble-rousers. To this day, lab directors keep a lecture handy in case of emergencies. Let us pray we never have to use it.
Fermilab sits on 7,000 acres of converted corn fields five miles east of Batavia, Illinois, about an hour's drive west of Chicago. At the Pine Street entrance to the grounds stands a giant steel sculpture created by Robert Wilson, who besides being the first director was pretty much responsible for the building of Fermilab, an artistic, architectural, and scientific triumph. The sculpture, entitled Broken Symmetry, consists of three arches curving upward, as if to intersect at a point fifty feet above the ground. They don't make it, at least not cleanly. The three arms meet, but in an almost haphazard fashion, as if they had been built by different contractors who weren't talking to each other. The sculpture has an "oops" feel to it—not unlike our present universe. If you walk around the sculpture, the giant steel work appears jarringly asymmetrical from every angle. But if you lie on your back directly beneath it and look straight up, you will enjoy the one vantage point from which the sculpture is symmetrical. Wilson's work of art suits Fermilab perfectly, since the job description of the physicists here is to search for clues to what they suspect is a hidden symmetry in what appears to be a very asymmetrical universe.
As you drive into the grounds, you come across the most prominent structure on the site. Wilson Hall, Fermilab's sixteen-story central laboratory building, sweeps upward from the flat, flat land, somewhat like a Durer drawing of hands held in prayer. The building was inspired by a cathedral Wilson visited in Beauvais, France, built in A.D. 1225. The Beauvais cathedral featured twin towers spanned by a chancel. Wilson Hall, completed in A.D. 1972, consists of twin towers (the two hands in prayer), joined by crossovers at several floors and one of the world's largest atriums. At the entrance to the high-rise is a reflecting pool with a tall obelisk at one end. The obelisk, Wilson's final artistic tribute to the lab, is known to all the researchers as Wilson's Last Construction.
Tangential to Wilson Hall is the raison d'être for the laboratory: the particle accelerator. Buried thirty feet beneath the prairie and describing a circle four miles around lies a stainless steel tube just a few inches in diameter. It weaves through a thousand superconducting magnets that guide protons around their circular track. The accelerator is filled with collisions and heat. Through this ring, protons race at near-light-speed velocities to their annihilation in head-to-head confrontations with their brethren antiprotons. These collisions momentarily generate temperatures of about 10,000 trillion (1016) degrees above absolute zero, vastly higher than those found at the core of the sun or in the furious explosion of a supernova. Scientists here are time travelers more legitimate than those you'll find in science fiction movies. The last time such temperatures were "natural" was a tiny fraction of a second after the Big Bang, the birth of the universe.
Though underground, the accelerator ring can easily be discerned from above because of a twenty-foot-high berm of earth on the ground above the ring. (Imagine a very skinny, four-mile-around bagel.) Many people assume the berm's purpose is to absorb radiation from the machine, but it's really there because Wilson was an aesthetic sort of guy. After all the work of building the accelerator, he was disappointed that he couldn't tell where it was. So when the workmen dug out holes for cooling ponds around the accelerator, he had them pile up the dirt in this immense circle. To accent the circle, Wilson created a ten-foot-wide canal around it and installed circulating pumps that fire fountains of water into the air. The canal is functional as well as visual; it carries the cooling water for the accelerator. The whole thing is strangely beautiful. In satellite photos taken from three hundred miles above the earth, the berm-and-waterway—looking like a perfect circle from that height—is the sharpest feature on the northern Illinois landscape.
The 660 acres of land enclosed by the accelerator ring are a curious throwback. The laboratory is restoring the prairie inside the ring. Much of the original tall prairie grass, nearly choked out by European grasses over the past two centuries, has been replanted, thanks to several hundred volunteers who have harvested seeds from prairie remnants in the Chicago area. Trumpeter swans, Canada geese, and sandhill cranes make their home in surface-water collection lakes that dot the ring's interior.
Across the road, north of the main ring, is another restoration project—a pasture where a herd of about a hundred buffalo roam. The herd is made up of animals brought from Colorado and South Dakota, along with a few indigenous to Illinois, although buffalo have not flourished in the Batavia area for eight hundred years. Before then, herds were commonplace over the prairie where physicists now roam. Archaeologists tell us that buffalo hunting over the present Fermilab grounds goes back nine thousand years, as evidenced by all the arrowheads found in the region. It appears that for centuries a tribe of Native Americans from the nearby Fox River sent their hunters up to what is now Fermilab, where they camped out, hunted down the animals, and carried them back to the riverside settlement.
Some people find the present-day buffalo a trifle unsettling. Once, when I was promoting the lab on the Phil Donahue show, a lady who lived near the facility phoned in. "Dr. Lederman makes the accelerator seem relatively harmless," she complained. "If it i
s, why do they have all those buffalo? We all know they're extremely sensitive to radioactive material." She thought the buffalo were like canaries in a mine shaft, only trained to detect radiation instead of coal gas. I guess she figured that I kept one eye on the herd from my office in the high-rise, ready to run for the parking lot should one of them keel over. In truth, the buffalo are just buffalo. A Geiger counter works much better as a radiation detector and eats much less hay.
Drive east on Pine Street, away from Wilson Hall, and you come to several other important facilities, including the collider detector facility (CDF), designed to make most of our discoveries about matter, and the newly constructed Richard P. Feynman Computer Center, named after the great Cal Tech theorist who died just a few years ago. Keep driving and eventually you come to Eola Road. Take a right and drive straight for a mile or so, and you'll see a 150-year-old farmhouse on the left. That's where I lived as director: 137 Eola Road. That's not an official address. It's just the number I chose to put on the house.
It was Richard Feynman, in fact, who suggested that all physicists put a sign up in their offices or homes to remind them of how much we don't know. The sign would say simply this: 137. One hundred thirty-seven is the inverse of something called the fine-structure constant. This number is related to the probability that an electron will emit or absorb a photon. The fine-structure constant also answers to the name alpha, and it can be arrived at by taking the square of the charge of the electron divided by the speed of light times Planck's constant. What all that verbiage means is that this one number, 137, contains the crux of electromagnetism (the electron), relativity (the velocity of light), and quantum theory (Planck's constant). It would be less unsettling if the relationship between all these important concepts turned out to be one or three or maybe a multiple of pi. But 137?
The God Particle Page 4
