Balance Shifts in Race for Physics’ Grail
Not since Shakespeare has there been so much ado about nothing:
The production involves billions of dollars, thousands of physicists, two of the world’s largest scientific laboratories and dozens of miles of racetracks for subatomic particles cruising at 99.9999% of the speed of light.
The star players are particle detectors the size of shopping malls--each with millions of channels of electronics hardened to military specifications, every connection custom-made and hand-wrought by groups of graduate students from Iowa to Minsk.
The stakes don’t get any higher. “I’ve only been obsessed about it for 20 years,” said physicist Chris Quigg of Fermi National Accelerator Laboratory, or Fermilab, outside Chicago.
The focus of all this brain and brawn is a particle known as the Higgs--a crucial piece of the underlying structure responsible for making the universe what it is today. Without this structure--the so-called Higgs field--the universe would still be as it was in the beginning of time, a featureless mist of particles and forces--everything the same, no gravity, no electricity, no quarks or atoms or stars.
Physicists believe the Higgs field shattered this primordial sameness by, in effect, freezing the mist into the vacuum that supports our universe today. It’s the Higgs that gives structure to the vacuum--what people normally think of as “nothing.” Without that structure, nothing else would exist. The vacuum is a nothing that determines everything.
The problem is that no one has seen hard evidence that the Higgs really exists. If it does, physicists should be able to knock loose a chunk of it in powerful collisions of subatomic particles.
So far, they haven’t succeeded. Until they do, the Higgs exists only in theory--leaving a gaping hole in the standard model of particle physics.
To find this elusive missing piece, Fermilab is locked in a fierce struggle with its European counterpart, the nuclear physics laboratory in Switzerland, known as CERN.
It’s a chance, Quigg said, to be the first to peer inside nature’s head. “There is no finer moment than the moment you understand something before anybody else does,” he said.
The competition to find the Higgs is almost uncannily like the fight over the presidency, physicists say. Both will ultimately turn on statistics; both have no clear end; both winners will reap enormous payoffs.
Finding the Higgs at Fermilab would be “a huge psychological boost,” Quigg said. On the other hand, if the prize goes to Europe, U.S. physicists fear that they could lose their bid to build the next generation of accelerators on American soil.
“For Fermilab, it’s a chance to cement its place in physics for the next 20 years, based on what we do in the next five,” said physicist John Womersley, spokesman for one of the Fermilab experiments. “If we don’t succeed, we can’t claim that we need to be here.”
As of now, things are looking up for physicists working on this side of the Atlantic. Last month, Fermilab was handed the discovery of the Higgs on a platter, some physicists say, when competitors at CERN temporarily dropped out of the race. The hints they had seen of the Higgs in their detectors last month were ultimately not enough to convince CERN’s director to halt the planned destruction of the current machine to make room for a new, much more powerful one.
The decision was agonizing. For weeks, petitions circulated, rumors flew, minds changed overnight; evidence that looked solid Wednesday evaporated by Thursday. And then it was over. Now CERN can only wait until their new machine--the Large Hadron Collider (LHC)--comes on line in 2006; and hope that Fermilab won’t get there first.
“It’s a Shakespearean tragedy,” said CERN spokesman Niel Calder. Like presidential candidates George W. Bush and Al Gore, “They were so close they could taste it,” he said. Now CERN must wait while the competition has its chance.
If the hints that the CERN accelerator saw were the real thing, Fermilab could make the actual sighting before the LHC comes on line.
But Fermilab’s victory is far from a sure thing. “It’s going to be tough,” Quigg said.
The quest for the Higgs is an unusual kind of competition. For one thing, it’s hard to say who’s on which team. Although CERN’s 20 member states are European, half of the physicists working there hail from other countries, most from the United States. And nearly a third of Fermilab’s scientists are non-U.S. citizens.
CERN theorist John Ellis compares it to the competition between baseball teams. “How many Yankees come from New York?” he asked.
For another thing, the two laboratories can’t race against each other in the normal sense. CERN will have to wait like a gymnast with a 9.8, sitting on her hands while her competitor earns a 9.9 to win the gold. Or, alternatively, falls off the bars.
“Suddenly, the eyes of the world are on us,” said Fermilab’s Franco Bedeschi, an Italian. “Any misstep we make, people will be asking, ‘Why?’ ”
“It’s going to be a long haul,” said Bedeschi’s colleague Al Goshaw. People are expecting them to find the Higgs right away, he said. But for now they’ll be doing all they can simply to get to know their completely rebuilt machines--back in service after a five-year, multimillion dollar make-over.
Many physicists at CERN are predictably unhappy about the brutal suspension of the lab’s chance to find the Higgs. One internal memo circulating recently complained that “CERN will look ridiculous to have missed this opportunity.”
Of course, physics is supposed to be impartial. It shouldn’t make any difference who finds it as long as it’s found.
“You might say, what difference does it make? We’re all brothers and sisters in the great search for truth,” said Calder. “On the other hand, grrrrrrrrr!”
Loss of European Experiments
Jason Nielsen is one of the American physicists now mourning the loss of his experiment at CERN. Still a graduate student at the University of Wisconsin, Nielson has nonetheless been one of the machine experts on ALEPH, the CERN detector that saw the first evidence of the Higgs and had a possible crack at its “discovery.”
“No more late nights baby-sitting for the detector,” he said recently, driving for perhaps the last time to visit ALEPH in its “pit” 140 meters underground.
The Alps light up in Day-Glo pink as the sun sets over the Jura Mountains to the west, newly dusted with the season’s first snow. The drive to the other side of the 17-mile-circumference ring takes him across the border from Switzerland into France, through small French towns and rolling green fields stacked with bales of hay and bordered by bright red and yellow autumn foliage.
Here, there is not much more than French countryside and particle physicists.
At the laboratory’s main complex back near Geneva, physicists sit at long tables in the cafeteria sipping wine and coffee, speaking more languages than most people can even name. The native English speakers alone babble in several distinct dialects, including Scot, Irish, English, Australian, Brooklyn, Texan.
There are more women physicists than evident at U.S. labs, many of them Italian. More children too. CERN is a nice place to work, with long vacations, a French pastry chef, and the kind of steady funding that is only a dream for U.S. physicists.
Now, however, much of CERN will be entering hibernation and physics’ center of gravity is slowly shifting to the Illinois prairie, where buffalo roam inside Fermilab’s main 4-mile-circumference ring. Nielsen, along with many of his colleagues, will probably be moving West. “Physics follow the data,” he said.
The move to Fermilab complicates the search for Higgs. For one thing, in the accelerator being dismantled at CERN, electrons and their antimatter counterparts--positrons--collided with each other. Both are “point particles,” with no internal structure. The collisions produced a clean burst of energy. Physicists know exactly what went in--making it relatively easy to deduce what came out.
Fermilab’s Tevatron, on the other hand, smashes protons into anti-protons. Each proton is a collection of three loosely attached quarks. That makes the collisions messy. “You don’t even know what’s going into the collision,” Quigg said. (The messiness is worth it because protons can be made to collide at much higher energies.)
When the Tevatron starts taking data again next spring, 99 tightly bunched clusters of protons will collide with an equal number of anti-protons 10 million times a second, causing a fireworks of particle creation. The result, said Goshaw, will be “a fire hose of information.”
To catch what comes out, two giant detectors embrace the collision points--the real guts of the enterprise.
“You’re touching nature in a real sense,” said Womersley. “Theorists are people who postulate what’s in nature’s head, but we’re up to our elbows in the insides of bodies.”
Obstacle Course for Flying Particles
The Collider Detector at Fermilab, or CDF, has just been brought out after a successful test run. The 12-ton door stands open, exposing some of the inner chambers, under flags of Japan, Taiwan, Italy, United States and Canada.
All particle detectors, at heart, are metal cylinders with caps, like corks, at both ends that can be removed for maintenance. The particles flying out from the collision point at the center have to make their way through an obstacle course of chambers that surround it like layers of an onion.
In the process, the particles get bent by super-strong magnetic fields, bounced into noxious gas molecules, zapped with high voltages, pushed through sieves of fine wires and generally digested in the thick guts of detectors that can stand six stories high.
These monsters look, and sound, almost alive. The thumps of the fans and vacuum systems pulse loudly through the cathedral-sized pits, while other components gurgle, hum, buzz; yellow lights flash warnings: danger. High tension. No flames.
Tubing and wires of every conceivable size carry gases, cooling water, power--the life support of the system. Tens of thousands of multicolored cables carry electronic signals out.
“This is where you come in the middle of the night when something doesn’t work,” Nielsen said. “Every one of these cables is somebody’s baby”--built by a graduate student somewhere like himself. “You feel [the connection] in your gut.”
Boxes of electronics bear the names of the institutions where students hand-built them: University of Wisconsin. Trieste. MPI (for Max Planck Institute, in Germany).
The signals captured in the detector eventually make their way into the control room, stacked with computer monitors (and in some cases, bottles of champagne--the fruits of past victories).
At the Collider Detector at Fermilab, the control room has its usual assortment of specialists: the “aces,” who are mostly post-docs; the “sci co” (pronounced psycho), or scientific coordinator; the s.o.s., or safety officer on shift.
But what they actually “see”-- or what anybody will actually “see” from all this mass of information--is only a tiny fraction of what is actually produced.
Of the 10 million collisions per second that will be produced in the Tevatron, for example, only a handful will get a careful look. Exactly which handful is a decision made by high-powered computers. Known as “trigger” systems, these computerized “sieves” throw out all of the ordinary, everyday stuff--and keep only the gems that might contain something unusual. Like Higgs boson, for example.
How do they know they haven’t thrown out a gem by mistake? They try to simulate every conceivable outcome of a collision on computers beforehand, so the trigger knows exactly what to look for. Still, throwing out something potentially precious is “a big worry,” Goshaw said. “You can be fooled.”
For every series of particle tracks that looks like it came from a Higgs, for example, there will be 10,000 very similar patterns of tracks that could come from some “ordinary” process--such as a couple of quarks turning into other particles.
Thus, proving the existence of the Higgs--like proving guilt using DNA evidence--will turn on statistics. Physicists need to get their probability of error down to about 1 in a million before they can claim a “discovery.”
For all the seeming hype associated with the discovery of the Higgs particle, its significance is hard to overstate. First proposed by Peter Higgs of the University of Edinburgh in 1964, it’s outgrown its original role and now does what is arguably the most important function in fundamental physics: It gives forces and particles identity. It changes the universe from an undifferentiated chaos into the structured cosmos of quarks and electrons and gravity and electricity we now inhabit.
“Knowing there is a Higgs says, yes, there is a field that can do [that], and it occurs in the way we thought,” Fermilab physicist Joe Lykken said.
To be sure, many physicists contend that the Higgs is so well established in theory--and by previous experiments at CERN--that its discovery today will be no big deal. “It’s like waiting for the other shoe to drop,” MIT physicist Frank Wilczek said.
Still, he conceded, “There is a magic about the particle that goes far beyond its physics. And they may find something completely different. Nature has the last word.”
Wherever--and whenever--the Higgs is found, the search itself is likely to have enormous effects on the field of particle physics--still hurting from the cancellation of the half-built Superconducting Supercollider, killed by Congress in 1993. Now nothing but a huge hole in the ground in Texas, the mammoth accelerator would surely have had the Higgs in hand by now, scientists believe. That lost opportunity makes the current search all the more poignant.
“I think we all feel some connection to this,” Quigg said. “It’s always amazing that we little humans can make up a story about the universe and find that it’s true.”
Or as Fermilab’s Harry Weerts put it even more bluntly: “We’ve been at this for 20 years. I want to find it, and I want to find it now.”
