Sam Ting is on a mission: find the other half of the universe.
- By Andrew Lawler
- Air & Space magazine, May 2001
High above the Florida dunes, a group of excited visitors clambers over the metal grates at the top of the space shuttle launch pad. As a cool winter wind blows and a pale, nearly full moon rises over the Atlantic, they chatter in French, German, Chinese, Italian, and Korean, snapping pictures with disposable cameras. No ordinary tourists, this group of VIP physicists is here on a working trip. Their usual haunts are vast underground tunnels near Geneva, Switzerland, that house gigantic particle-smashing accelerators central to their research. But an unusual experiment slated to be launched in two years from this spot at NASA’s Kennedy Space Center has brought the scientists out of their holes for a look at the stars.
The Pied Piper luring them to this upper world is Sam Ting of the Mass-achusetts Institute of Technology, a Nobel prize winner famous for thumbing his nose at scientific orthodoxy. The trim and dapper 65-year-old physicist has set his sights on finding evidence of a long-theorized anti-matter universe—a chase that many scientists, including some on his own research team, say is extremely long on odds. Undaunted, Ting has deftly used a combination of political savvy, his own reputation, and managerial muscle to persuade 16 governments and hundreds of physicists and engineers around the world to join him in a multimillion dollar quest to find exotic particles that may not even exist.
Ting’s plan is to attach a massive magnet called the Alpha Magnetic Spectrometer (AMS) to the outside of the International Space Station, where he hopes it will attract passing bits of anti-matter—particles with an electrical charge opposite that of ordinary matter. If such anti-atoms exist and can be captured, the finding would solve one of the great mysteries of modern cosmology—namely, what happened to all the anti-matter that should have been created in equal parts with matter at the time of the Big Bang.
Never mind that in the past decade, dozens of balloon flights have tried to find primordial anti-atoms and failed. “No risk, no reward” is the unofficial rationale behind the AMS. “This program clearly has a very low probability of finding primordial anti-matter,” says Hans Hofer, a longtime colleague of Ting’s at the Swiss Federal Institute of Technology in Zurich. “But if you find it, you’ll be famous.”
And fame is as coveted in the research world as it is in Hollywood. Ting is certainly a research superstar, but he has also earned a reputation for abrasive toughness that rubs many the wrong way. No surprise, then, that astrophysicists resent his sudden appearance on their turf—the heavens—and the way he used his connections to win the support of NASA Administrator Dan Goldin. Many high-energy physicists see the space station experiment as being on the fringe of legitimate research, while to others, the AMS is nothing more than a big gamble by a big ego to grab headlines. Even his own colleagues joke that the program’s acronym is a deliberate scramble of Ting’s first name.
But Ting says his venture ultimately is not about turf or headlines but about the excitement of exploration. The challenge of being the first to discover primordial anti-matter forged in distant anti-galaxies is simply too tempting to pass up. “And if you don’t do it,” he says, “someone will do it better.”
As early as 1898, British physicist Arthur Schuster suggested the existence of “anti-atoms” that mirror the building blocks of ordinary matter. In the early 1930s, his countryman Paul Dirac described the behavior of electrons in equations that for the first time married Einstein’s relativity theory with the new Alice in Wonderland concepts of quantum mechanics. One curious byproduct of Dirac’s equations: They required, along with ordinary, negatively charged electrons, the existence of anti-electrons with a positive charge—anti-matter.
Proof came almost immediately. In 1932, physicist Carl Anderson of the California Institute of Technology discovered one of these “positrons” in a laboratory cloud chamber while studying the tracks of cosmic rays—very-high-energy particles streaming in from space. Half a century later, German physicist Werner Heisenberg would call Anderson’s discovery, which had won him a Nobel prize, “perhaps the biggest jump of all the big jumps in physics in our century.”
By the mid-1950s, physicists using large particle colliders had succeeded in manufacturing an anti-
proton by smashing together two ordinary protons at fantastic speeds. Since then, giant accelerators have sprung up—or, more accurately, sprung down—in Europe, the United States, Russia, and China. In 1995, researchers at a vast underground complex called CERN (Centre Européen de Recherche Nucléaire), located on the border of Switzerland and France, opened a new door into the anti-world. By colliding anti-protons and xenon atoms, they produced anti-atoms of the most basic element, hydrogen—one anti-proton and one positron. The anti-atoms lasted only 0.00000004 second before being annihilated by ordinary matter, but they left signals that confirmed their existence.
Scientists have also seen anti-hydrogen in nature. Mimicking what happens in accelerators, cosmic ray particles crashing into particles in the atmosphere produce a secondary shower of anti-protons and positrons. But high-altitude balloons have yet to detect anti-atoms of heavier elements—which could only be forged inside distant anti-matter stars by nuclear fusion, just as ordinary carbon, iron, and other elements are created in the furnaces of ordinary stars. In other words, we see no evidence of anti-stars and anti-galaxies wheeling in the sky. And that presents astrophysicists, who like symmetry, with an embarrassing question: If the birth of the universe created matter and anti-matter in equal parts, as Dirac’s equations demand, where’s the other half?
The best explanation offered to date is that our universe is all that remains of the mutual annihilation of matter and anti-matter that took place shortly after the Big Bang. The two materials duked it out until only a small amount of matter—what we today call the universe—was left standing. That means matter was granted some slight advantage. Scientists call this puzzlement the charge parity violation—“CP violation” for short.
High-energy physicists are busy investigating the theory in accelerators, while astrophysicists look for signs of anti-matter stars and galaxies. Until one or the other succeeds, says Steve Ahlen, a Boston University physicist involved in the early stages of the AMS project, the jury is still out: “No one really can demonstrate how the universe could have no anti-matter,” he says.
Enter an experimentalist like Ting, who has little patience with theorizing. “If you listen to the theorists, you would do nothing,” he says. So when the anti-matter question caught his attention in 1994, Ting ignored the warnings of colleagues and starting working on ideas that could turn up primordial anti-matter.
Though his is the most ambitious, it is not the first. As far back as the 1970s, fellow Nobelist Luis Alvarez was on the trail. More recently, two high-altitude instruments—the Balloon-borne Experiment with a Superconducting Solenoidal magnet (BESS), run by NASA and Japanese researchers, and the High-Energy Anti-matter Telescope (HEAT), sponsored by a consortium of universities, have counted about 1,000 anti-protons to date, the results of cosmic ray collisions in the atmosphere. But still no sign of heavier anti-atoms forged inside anti-stars. The CP theorists doubt they are there to be discovered, and even some experimentalists have grave reservations about finding them.
One reason is distance. No significant amount of anti-matter is believed to exist in our own supercluster of galaxies, or within about 30 million light-years of Earth. If it did, we would see enormous flashes of gamma rays from the mutual destruction of matter and anti-matter—and we don’t. Any anti-atoms created in anti-galaxies must have originated near the edge of the visible universe. In theory, those anti-particles could have crossed that vast distance to reach Earth, but most would have been trapped by the magnetic fields surrounding stars and galaxies along the way. “Even if anti-stars and anti-galaxies exist, they are so far away it would be quite hard for particles to come close enough for observation,” laments Dietrich Müller, a University of Chicago physicist and spokesperson for the HEAT project.
Yet Ting has made a career of proving the common wisdom wrong. His proposal in the early 1970s to search for a new kind of particle that decays into pairs of electrons and positrons was turned down by several accelerator committees; he was finally given a shot at the Brookhaven National Laboratory on Long Island. By 1974, after 18 months of experiments, he had found what he was looking for. Nearly simultaneously, Burton Richter of Stanford found the same thing, and they shared the Nobel Prize for discovering the “J-psi” particle two years later.
Ting was only 40. It was an astonishing achievement for a Chinese immigrant who had arrived in Ann Arbor, Michigan, two decades earlier with only rudimentary English and $100 in his pocket. He quickly earned scholarships that led to a physics doctorate in 1962. “He was a young man in a hurry,” recalls Lawrence Jones, who had co-chaired Ting’s thesis committee and is now an emeritus professor at the University of Michigan. Ting joined the MIT faculty in 1969, and his interest in particle physics took him frequently to CERN in Geneva. There he came to lead one of the costliest basic research projects in history: the L3 Experiment, which involved nearly 500 physicists from 40 institutions and cost $200 million for equipment alone.
By 1994, the peripatetic Ting was in search of a new challenge. The collider used for his experiment was due to be shut down to make way for a larger machine, so his work at CERN to discover yet more microparticles was soon to end. The U.S. Congress and the new Clinton administration had killed the massive Superconducting Super Collider the year before. And Ting’s proposal for a massive experiment using CERN’s next big accelerator, the Large Hadron Collider, had been rejected.
That left few options in the traditional field of high-energy physics. So in early 1994, Ting called together a small band of colleagues. It was one of those rare moments when researchers have a chance to be wildly creative. “For a couple of months we sat around and gave any good idea a hearing—as well as a lot of bad ideas,” recalls Peter Fisher, an MIT collaborator. “It was an extraordinary time, sitting around with all these great minds.” Boston University’s Ahlen pushed for building a massive collector deep in a Tibetan canyon to search for gamma rays from space, while others proposed spacecraft that would carry sophisticated particle detectors.
The Tibetan idea was rejected as impractical—too many dump-truck loads needed, too many problems with theft and bureaucracy. Launching a spacecraft seemed daunting too, although the Russian government had cheap rockets for sale. Ting jetted off to Moscow to discuss a deal. He also asked Roald Sagdeev, the former head of the famed IKI space science institute in Moscow and now a physicist at the University of Maryland, to listen to the group’s ideas. Intrigued by the anti-matter proposal, Sagdeev called NASA’s Goldin, who promptly invited Ting for a visit. “It was really a summons to Washington,” says Fisher. “And not many people summon Sam Ting.”
The two men were well matched to make a deal. Ting wanted support for his mission, and Goldin desperately wanted scientific credibility for his space station, which was under fire from Congress and critics for being a $100 billion waste of time. Just one year before, the station had narrowly avoided cancellation. Goldin had a platform on which to hang a big magnet, and Ting was a big name.
Both men also have reputations as out-of-the-box thinkers impatient with bureaucracy. Ting wanted control over the project, and Goldin knew that the standard NASA science and engineering reviews would bog the proposal down and possibly kill it. For one thing, the AMS would have to get in line with other projects. Standards for flying NASA equipment were also stringent. “Mr. Goldin said, ‘You’d better go through the Department of Energy—if you go through NASA you’ll never get out,’ ” recalls Ting with a laugh.
So the easier route was to keep the anti-matter search a Department of Energy project, with NASA providing the launch, real estate on the space station, and some operational help. That way, the AMS wouldn’t compete directly with other space missions for funding. In turn, Ting promised his Department of Energy sponsors that he would get the bulk of his funding from overseas, leaving the department obligated only to pay a modest $7 million—a bargain, given the cost of most high-energy-physics experiments. For Goldin, it was a no-lose situation. “If it doesn’t work, then it’s a Department of Energy payload. If it does, then NASA will take all the credit,” jokes MIT’s Fisher.
Ting and his small team closeted themselves for two months, putting together an extensive proposal for the AMS. To expand its scientific goals beyond just the search for primordial anti-matter, the team made room for experiments to look for evidence of dark matter, which likely makes up some 90 percent of all ordinary matter, and to investigate the origin of cosmic rays. For Ting, these bread-and-butter experiments had the benefit of winning over more conventional scientists. “I’m personally not very interested in this,” he admits.
After a series of formal reviews, the proposal won approval from independent panels of scientists. Many critics still grumble about the fast-track decision, saying it was politically motivated. AMS collaborators bristle at the claim, saying the program went through traditional peer review and is taking no money from other U.S. projects, as its funding comes mostly from European countries. The decision was, however, sobering news for the small cadre of astrophysicists conducting balloon-borne anti-matter searches. Ting’s project spelled the beginning of the end for those efforts, says Jonathan Ormes, who heads the high-energy astrophysics lab at NASA’s Goddard Space Flight Center in Maryland. It would be nearly impossible to compete with the AMS, with its more powerful magnet and far longer life.
NASA and Ting’s group also agreed to first conduct a test flight on the space shuttle. They wanted to be sure that the technology would work, that it would be safe, and that it was well tested. “I didn’t understand then how hostile the space environment is,” Ting admits. Most high-energy physics experiments work perfectly well in normal temperatures and atmospheric conditions, and can be easily modified if operators need to tweak the hardware. The AMS would be strapped to trusswork 250 miles in space, would be subjected to brutal sunlight and freezing shadow, and, once launched, would offer scientists only limited access to its systems.
So with no previous spaceflight experience, Ting set out to raise a team and the money to design, build, test, and fly the first experiment. The challenge sent the physicist on a frenetic round-the-world mission to lobby colleagues and their government ministers. The speed with which he worked astonished NASA managers, who can spend 15 years or more getting their projects from concept to orbit.
The instrument Ting’s team designed for the shuttle flight is a two-ton cylindrical magnet that is about three feet high and three feet in diameter at the core. The magnet creates a uniform field; a piece of matter entering the bore of the cylinder will bend one way, while oppositely charged anti-matter will bend another. Arranged like parallel shelves inside the bore hole are a series of highly sensitive detector plates that measure a particle’s speed, momentum, charge, and path. A system of counters sorts electrons from anti-protons, and another counter rejects those particles that leave or enter through the inner shell of the magnet, to rule out particles bouncing off the AMS itself. Colliding particles of dark matter—the invisible stuff whose presence physicists infer from its gravitational effect on the visible universe—also should produce telltale anti-protons, positrons, and gamma rays, and the AMS includes instruments to measure the spectrum of such particles. The same instruments can help characterize incoming cosmic ray particles. All data is transmitted directly to NASA’s Johnson Space Center, with no assistance from the astronauts.
Pulling all of these pieces together required help from more than a dozen countries. To produce the strong magnetic field he had in mind, Ting had to go to China, the primary source of a high-grade neodymium-iron-boron alloy favored for making powerful magnets. His fluent Chinese helped him win a quick endorsement from the Chinese Academy of Sciences, which agreed to build the magnet. He assembled a team of Germans, Italians, Finns, and Swiss to provide the silicon tracker plates, while German and Italian teams coordinated the design and construction of the counters. Engineers and scientists from more than half a dozen countries pitched in to provide electronics, software, and ground support systems.
The 1998 shuttle mission STS-91 proved a success, save for an annoying problem with downlinking data from orbit. Although the week-long test run did not find any evidence of primordial anti-matter, it did spot anti-protons, and all the instrument’s systems worked as planned. So Ting had a green light to build the second-generation instrument, which will be attached to the outside of the space station in 2003 for a three-year experi-
ment — long enough, he hopes, for a wayward anti-particle from an anti-star to find its way to his magnet.
Like the conductor of a complex symphony, Ting manages every aspect of the project himself. His reputation as a control freak was on display at a recent meeting in a windowless room at Kennedy Space Center. Sitting front and center, he kept his speakers on a tight schedule during the brutal three-day gathering. “Avanti! Avanti!” he urged an Italian colleague who paused to answer a question. Weary physicists eager for a coffee break would make a move for the door, only to be told by a smiling Ting, “No coffee until after the next presentation!”
But Ting also knows to add levity to what often becomes a grinding nuts-and-bolts process. He bet one Italian colleague five dollars that he couldn’t set up a Powerpoint presentation with his laptop. When the Italian succeeded, Ting reluctantly paid him off, but later got revenge by hiding the same laptop, making his frantic colleague search everywhere.
His team members, which include some of the most distinguished physicists in the world, submit to Ting’s antics because they trust him to get the job done. “He’s driven purely by science,” says Roberto Battiston, a physicist at Perugia University in Italy. “Even if a technical decision means political disaster, he doesn’t care.”
Ting knows that simply being an autocrat, without a good argument to back up his judgments, would never work. “In an international collaboration, you cannot order people around,” he says. “You can only convince people, because they do not report financially to you.” Still, it’s a far cry from the multi-national committees that typically run Big Science projects, with their endless meetings and consensus building. “He’s not democratic at all,” says physicist Cristina Vannini of the National Institute of Nuclear Physics in Pisa, Italy. “Democracy doesn’t work—there must be one person who decides.”
His toughest call to date, Ting recalls, was to rule out using the Chinese-built magnet for the space station flight—a major blow for Chinese re-searchers. Instead, the team turned to a far more powerful superconducting magnet, which will be much more expensive. Ting also regrets that Russia was unable to join the program for lack of funds.
Russia is, however, involved in another anti-matter experiment, which rivals—or complements, depending on your viewpoint—the AMS. Called PAMELA, the project is slated to put a much smaller magnet into space on a free-flying satellite next year, although it likely will be delayed. Russia is supposed to provide the launch vehicle, while a small team of mostly Italian researchers is building the device. Since it has to carry its own power source, the magnet is much smaller and has a shorter lifetime than the AMS’s magnet. Ting also points out that PAMELA will only have one-thousandth the sensitivity of his experiment. But some of his collaborators say that while it lacks the sophistication of their device, the Russian instrument could provide additional evidence of anti-matter.
Ting, though, is clearly aiming to be first. He’s already pondering what a third AMS mission would look like. And he seems untroubled by the skeptics. “He doesn’t care,” says Ahlen. “He’s happiest just exploring.”
If his gamble pays off, Ting may someday have big news to report to the world. In the meantime, the particle physicists on his team are looking outward to the stars, and astrophysicists are paying closer attention to their colleagues from underground. That alone may be progress for those with the difficult job of explaining why half the universe has gone missing.