In the popular view, scientists ply their trade in sterile labs surrounded by delicate glassware and elegant equipment, where they ask polite questions of Nature and follow equations to their logical conclusions.
The image that comes to mind isn’t exactly “Braveheart.”
Yet among the many scientists who push the limits of knowledge every day, there are those who go even further--challenging long-held theories and attacking hard problems that ultimately may not have solutions.
This forefront science is no place for sissies. Conquering conventional wisdom requires a kind of recklessness that encourages taking wild leaps over long-established boundaries, climbing out on tenuous limbs that frequently buckle and snap.
In a sense, it can’t be otherwise. There are no road signs in uncharted territory, no footprints to follow in places where no one has ventured before. Scientists seeking truth in these dark corners are the opposite of the man who looks for his lost keys under the lamppost because it is the only place he can see.
Unconventional ideas also invite attack--or worse, dismissal--by professional colleagues. No one would publish biologist Rachel Carson’s work when she first documented the link between dying species of birds and fish and the pesticide DDT. No one, at first, believed Einstein or Darwin. “The more adventuresome and different the proposal,” said Harvard science historian Gerald Holton, “the more likely it is to run into extraordinary resistance.”
One doesn’t have to dig into the history books to find scientists willing to stick out their necks to explore the unknown. Presently, in California alone, dozens of scientists are risking reputation and job security to learn what lies beyond the lamppost, to invent new and clever ways to see in the dark.
Take physicist Andrew Strominger of UC Santa Barbara, who recently found a “missing link” that connected two seemingly unconnected areas of physics: black holes and “strings.”
Black holes are enormous concentrations of gravity that warp time and space (or space-time, as the twin entity is known) into sinkholes that capture anything that wanders near. Strings are infinitesimally tiny loops of some unknown fundamental stuff that some physicists think add up in interlocking patterns to create everything in the universe.
Strominger saw a connection where other people just saw barren ground--in essence, a mathematical bridge that led from black holes to strings. And the link he and his colleagues forged looks like a critical step on the way to understanding how the universe is put together.
Strominger still seems somewhat befuddled by his current string of successes. To hear him talk, one wouldn’t know that he’s suddenly been propelled to the top of his field.
“Lots of people predicted I wouldn’t get anywhere,” he says. “It’s still hard even for me to know how I managed to put [the discovery] together. It doesn’t seem rational. When I look back, I have the sensation that I’m not smart enough to figure that all out.”
Curiously, this willingness to feel lost seems critical to forefront science. Mathematician Sylvan Cappell of New York University’s Courant Institute thinks this befuddlement requirement goes a long way toward explaining why younger scientists often do the most creative work. “When you’re learning something new, you always feel stupid,” he said, and risk your self-esteem by feeling like a fool. This allows you to take chances you might not otherwise take. “But when you get an office and a secretary, you don’t want to feel stupid anymore.” So you play it safe, making fewer breakthroughs.
What keeps these researchers going is a compelling urge to know that goes far beyond reason. “You have to really, really, REALLY want to the know the answer,” Strominger said. “You have to be obsessed. You have to be persuaded that there is an answer. The ones who’ve done best in this field are the ones who have faith.”
Or as the late physicist Frank Oppenheimer liked to put it: “Understanding is a lot like sex. It has a practical purpose, but that’s not why people do it normally.”
Strominger’s field is about as esoteric--yet fundamental--as physics gets. The question he’s after is: What are the ultimate laws that rule the universe?
Physicists know fairly well the quantum mechanical laws that rule atoms and molecules. They know the law of gravity that rules planets and stars and the universe at large.
The problem is, the laws that rule the realm of the small and the laws that rule the large don’t mesh. Using quantum theory to understand gravity makes as much sense as trying solve a crossword puzzle with the key to your door. When physicists try to put the two realms together, the answers they get are nonsense--like adding 2 plus 2 to get infinity.
Strominger and his colleagues found a hidden connection between these two disparate realms, and set off an explosion of new research in the process. In short, the scientists found that fundamental entities called strings and black holes may be different aspects of the same thing.
“It’s a very exciting development,” said Caltech physicist John Schwarz, one of the founders of string theory, and it has made Strominger “one of the top half dozen people in this business.”
Strominger thinks he’s been successful in part because he keeps focused on the big picture, avoiding the sidetracking seduction of elegant details. “What really excites me is trying to get the answers to the big questions,” he said.
He also relies on tactics that sound disconcertingly unscientific. “I sort of smell things, for reasons I can’t explain.”
In relying on his senses, Strominger is in good company. Albert Einstein said he heeded an “inner voice.” Charles Darwin wrote: “I trust to a sort of instinct and God knows can seldom give any reason for my remarks.”
According to string theory, the fundamental building blocks of the universe are not particles or forces but tiny loops that vibrate in 10 dimensions. Just as a four-string violin creates symphonies of sound, the harmonics of these higher dimensional strings create everything in the universe.
Physicists like the mathematical beauty of string theory because it banishes the absurdities that pop up when quantum mechanics and gravity combine. Mostly, they like the fact that string theory is highly symmetrical.
Symmetries enable physicists to determine what fundamental truths lie beneath superficial differences. Because string theory has so much symmetry, it can accommodate the disparate faces of nature displayed by gravity and quantum theory.
But string theory is just beginning to be understood. And in the meantime, there is no way to prove, experimentally, whether or not it is true, because the strings are a hundred billion billion times smaller than a proton, which puts them far beyond the reach of any currently conceivable experiment.
“You can’t think of experiments that will solve this problem,” Strominger said, “so many reasonable people take the view that it’s impossible. . . . My thesis advisor told me I would never get a job if I worked on this problem.”
Strominger’s thesis advisor has some influential company in his view that string theory is so much useless tilting at equations. But many of the brightest minds in physics are convinced of its ultimate truth--in large part because of its mathematical beauty. In the history of science, beauty has proved itself a reliable guide to truth.
Particles called positrons, for example--now routinely used in medical procedures--first revealed themselves as an unexpected asymmetry in an equation. The search for symmetry also led to the discovery of quarks, the most fundamental building blocks of matter.
The one phenomenon in the universe that string theory didn’t fully encompass until Strominger and his colleagues came along was black holes--those deep wells in space-time whose gravitational pull is so strong not even light can escape. When the physicists found a way to prove that strings and black holes were different aspects of the same thing, the whole field of string theory received an enormous shot in the arm. Even more important to a lot of physicists, Strominger found a perfect mathematical fit between strings and physicist Stephen Hawking’s astonishing discovery that black holes can actually radiate “heat.” The connection brought physicists closer to an overarching theory that could explain everything in nature.
Like a mobile twisting in the wind showing different faces to a viewer, black holes and strings turned out to be different faces of the cosmic sculpture.
And that’s what got everyone excited: “Different ideas turned out to be the same idea,” Strominger said. “All got orchestrated together so that they played in harmonious ways.”
Although no one is sure yet where this work will lead, it’s similar in many ways to the discovery of the nature of light as electromagnetic radiation. People had thought that electricity and magnetism, too, were entirely different entities. Making the connection between the two led to most familiar 20th century technology.
The details of how Strominger and collaborators forged the link are highly mathematical arguments only a physicist could love. Yet the general idea, he says, is much like the change that takes place when water turns to ice: If you put water in a box and drop the temperature to below freezing, you get a chunk of ice. If you put a hypothetical string into a theoretical box, and change certain aspects of its environment, you can get a black hole.
Of course, this is all done through mathematics. But as Strominger points out, H2O is mathematical, too. “You could conclude that water turns to ice [just with equations], without doing an experiment,” he said. “But with string theory, all you have is equations.”
Part of the reason Strominger was able to make the connection between strings and black holes was that he ventured outside of familiar territory. Not many string theorists were thinking of black holes at the time, he said.
This kind of wandering into other scientists’ backyards is common in the forefront of science. It gives the fresh perspective it takes to see things in an entirely different light. But it also adds to the general sense of befuddlement.
“For a long time, I felt I was on a different wavelength from anyone else,” Strominger said. “When I’m at a seminar, I always have the feeling other people are picking it up faster.”
Rather than tackle the problem head-on, he opened his mind and allowed the theory to explain itself to him. “I don’t feel like there was some Herculean task, where I worked hard and learned things,” he said. “It was more like the theory explained itself to us. The theory is much cleverer than the people trying to discover it. So instead of attacking it, you listen for clues. The people who do the best work are the listeners.”
Strominger knows he sounds more like a psychic channeler than a physicist when he talks like this. “I feel like that sometimes,” he laughs. “The sensation I have is that the theory is giving us all the clues as to how it’s put together, and it will speak to us on its own terms.”
Listening to instinct is not uncommon in science, either. “No discovery of great importance has ever been made by logical deduction,” writes C. Radhakrisna Rao, a much-honored statistician at Pennsylvania State University. “A necessary condition for creativity is to let the mind wander unfettered by the rigidities of accepted knowledge.”
Mostly what guides Strominger is a sense of aesthetics, of what would be the most satisfying possible answer to the problem. Then he works backward toward a solution. "[Another physicist] would say: If A and B, then C. And he’d set out to prove it. I would say: Gosh, Wouldn’t C be nice? And then try to prove it,” Strominger said.
But relying on instinct means scientists never know for sure if they’re on the right track until the work is well on its way to conclusion. “At least 90% of the things I try don’t work,” Strominger said. “There is a chance that this is all a wild-goose chase.”
He has to walk the line between faith in his own instinct, opinions of others and the chance that he might be wasting his time chasing dead ends. “It’s important to have faith in your own ideas and stick to them doggedly,” he said. “But there’s a fine line between that and being bullheaded.”
And Strominger does most of his walking alone, on a path that runs along the Pacific Ocean and around a quiet lagoon, with only ducks and egrets for company. Back in his office--on the phone, or via e-mail--he works closely with several colleagues--in particular, Briane Greene of Cornell, Dave Morrison of Duke and Cumrun Vafa of Harvard.
But theoretical physics is a lonely business--especially when a good number of your colleagues think the ideas you’re working on are a waste of time.
There’s a good reason for this resistance to new ideas. As Harvard’s Holton points out, if science didn’t demand proof of new ideas, “They’d [accept] every wind that blows.” Yet the period between getting an idea and proving it can be agonizing for a scientist.
While Strominger probably doesn’t have to worry much about job security anymore, many scientists in his position do. Employers don’t want to throw good money after half-baked ideas, which means it can be hard for cutting-edge scientists to get jobs and promotions.
As in most fields, a group of senior people decides the professional fate of everyone, Strominger said. And since researchers pushing back frontiers have to make things up as they go along, it’s hard, if not impossible, for senior colleagues to judge what they do. “By definition, they don’t know what you’re doing. Because it doesn’t exist,” Strominger said.
String theory has gained adherents in recent years, with more young physicists believing it just might be the answer they’re looking for. About one-third of the UC Santa Barbara graduate school class of 20 students is interested in strings, Strominger said. “A few years ago, it would have been one or two.”
Most of these probably will drop out, he said. “They’ll get worried. It’s risky.”
But some will hang in there, getting seduced as he was by the “fantastic beauty” of how the laws of physics hang together.
“People will never give up. Someone’s always going to want to answer this question. And sooner or later, they’ll get it.”