Princeton, N.J. -- Edward Witten, who may be the smartest man in the world, seems slightly puzzled by the question put to him: How, his interrogator wants to know, would he describe a typical day in the life of a theoretical physicist? The question is followed by a long silence, one that threatens to turn uncomfortable. It fills his large, corner office at the Institute for Advanced Study, a theoretical research center that is home to a small group of the world's finest thinkers.
Which is what Dr. Witten is doing right now: thinking before he answers the question. His eyes, focused somewhere in the area of his shoes, are half-closed behind his thick, dark-rimmed glasses. The minutes tick by. Finally an answer surfaces.
"Well, you spend most of your time hanging around and doing nothing," says the 43-year-old physicist, who spent the first 18 years of his life hanging around Baltimore. "But occasionally you get an idea." He pauses for a long time, a habit he has, and then smiles. It is a shy, appealing smile, one that allows a brief glimpse of the person residing inside the otherworldly physicist.
"That's the best I can describe what a day is like," he says finally.
It also best describes the way Dr. Witten answers questions that don't relate directly to the extraordinarily complicated ideas that occupy his mind. Polite, reserved and formal -- but never less than kind and patient -- Dr. Witten conveys the impression of a man not given to introspection about himself or how he operates in the world. It is how the natural world operates, how the forces of nature work, that engages Dr. Witten's interest.
Most questions about details of his life outside the field of physics are met either with short shrift or, worse yet, answered in a way that delivers the interviewer to a dead end. He is a man, one suspects, who wants to know but does not necessarily want to be known.
Accordingly, you are likely to hear more, much more, about the occasional ideas that come to Edward Witten while he's hanging around the institute doing nothing. Ideas with names like string theory, supersymmetry, superstrings and other cutting-edge work in physics and math; ideas that have earned him comparisons to Einstein, who worked at the institute from 1933 to 1955, and Newton, who surely would have worked at the institute had it existed 300 years ago; ideas that cause other physicists and mathematicians to shake their heads in awe.
But wait a minute. It turns out Dr. Witten is not quite finished answering the question about a day in the life of a theoretical physicist. It turns out he's still thinking about it and has more to say, a soliloquy of sorts delivered in his soft, staccato voice, about what a day at the office is like for him:
For instance, today is a little unusual. I got back from a few weeks abroad, I got over jet lag, there was a conference for the last three days, so today is the first day of the rest of my life. And there's this whole mishmash of things that haven't been solved. Of course, there are big problems you'd like to solve but they're too difficult. So you can't work on them on any given day. If you did that, you'd really just stare all day at a blank sheet of paper. I've spent more than my share of those days.
Perhaps. But Edward Witten has also produced more than his share of important theory -- no, make that revolutionary theory -- to the field of elementary particle physics.
"I would say he's the most influential theoretical physicist or mathematician in the world," says John H. Schwarz, a theoretical physicist at the California Institute of Technology, who is a pioneer in the area of string theory. "And I think this has been the consensus among theoretical physicists -- and most mathematicians -- for a long time."
"He shows the direction for the rest of us," says Rutgers physicist Nathan Seiberg, who recently collaborated with Dr. Witten on a series of groundbreaking papers.
Of course, none of this comes as a surprise to those who knew Edward Witten when he was growing up in Northwest Baltimore. At Park School, for instance, a classmate remembers how Edward -- who had skipped a couple of grades at Wellwood Elementary School and Sudbrook Junior High before arriving at Park in the ninth grade -- quickly was recognized as brilliant.
"I suppose it's common that kids in any high school sit around talking about who the smartest person in the class is," says Peter Baida, one of Edward Witten's closest friends at the time. "But we used to sit around -- when Edward wasn't there -- and talk about how he was the smartest person in the world."
Mr. Baida, who is now a fund-raiser for Memorial Sloan-Kettering Cancer Center, laughs at the memory. "And it turned out we were right. He actually is the smartest person in the world."
Whether or not Edward Witten is the smartest person in the world is, of course, unprovable. And ultimately unimportant. Certainly it is to him. He dismisses with a shrug all suggestions of comparisons to Einstein and Newton and to the fact that he is currently the most cited physicist in the world.
"Well, I don't read the newspapers, but I'm sure there are lots of other well-known mathematicians and physicists who are cited the same way by the press," Dr. Witten says, his voice edged with a shy humor. "So, I think we have to take this with a grain of salt."
Edward Witten, by the way, looks like a genius. His dark hair, which appears to be in the process of an electrical charge, rises straight up from his high forehead. His eyes are lively and penetrating but seldom make direct contact; they seem always to be looking at something the rest of us can't see. Dressed in an open-necked shirt and cotton pants, he looks more like a graduate student than a member of the elite, 22-person institute faculty.
(It should be noted, however, that there are an additional 150 to 170 scholars working at the institute, but, unlike permanent faculty, they come and go.)
Adding to the "genius" legend that surrounds Dr. Witten are tales of how he works out his complex calculations. Things like computers, pencils and paper do not play an important role in the life of his mind.
"I have a tendency, more than most other physicists, to try to figure out everything all at once, before I publish," Dr. Witten says. "And even to try to figure out everything in my head, without pencil and paper."
He lets out a laugh. "And even though I may occasionally have some success in that direction, trying to be too ambitious in that way leads many times to my failing to finish things. It's always one of my New Year's resolutions: to try to be more concrete, to keep my feet on the ground. . . . I have to say that, to my way of thinking, my main weakness is that I don't always keep my feet on the ground enough."
He declines to comment on what he judges to be his main strength, saying, "For the most part you will have to get that from other people."
Physicist Nathan Seiberg offers his analysis of the source of Dr. Witten's preeminence in his field: "The main strength is that he's powerful in everything. Both in math -- the most sophisticated math -- and physics. In physics one needs physical intuition. And he has remarkable physics intuition as well as complete control over the math that is needed. And in that respect I think he's unique."
Although genius is a word that has little or no currency among scientists, it is a word often applied to Dr. Witten. But not by his Italian-born wife, physicist Chiara Nappi. She doesn't believe in the concept of geniuses. Still, she says: "I think Ed comes as close as you can get to being a genius. But what I think Ed really is is an accident. And accidents like Ed don't happen so easily."
Ms. Nappi, a warm, outgoing woman who is an elementary particle physicist at the institute, means this description of her husband as the highest possible compliment. Few would argue with her assessment, although they might rearrange the vocabulary a bit.
She also has her own idea of what makes her husband unique in his field.
"I always have this view of how he works as compared to other people," she says. "It's like with Ed you have a field which is completely illuminated, totally lit up, so he just has to look around and figure out the connections. For most other people it's dark, or mostly dark, and you go with a flashlight until you find something that makes a connection with what you have seen before. But it comes natural to Ed to be able to make a connection. And this is an advantage."
Before we move on to supersymmetry accelerators, quark confinement and other good stuff like that, let's move back through time, back to Edward Witten's formative years in Baltimore. A good place to begin tracing the trajectory of young Edward's journey to the top of the physics world might be with his father, physicist Louis Witten.
"I would talk to him about scientific subjects the way I would talk to adults, and he would understand what I was talking about," says Dr. Witten, now professor emeritus at the University of Cincinnati.
His son, by the way, was a preschooler at the time of these talks.
When young Edward did get around to going to school, says his aunt, Ethel Klavens of Pikesville, he was always ahead of his teachers. "The public schools didn't know what to do with him," she says. "They skipped him from the fifth to the seventh grade, and then when he was at Park School, they had a professor from Hopkins teaching him math."
Mrs. Klavens remembers teaching her nephew how to play bridge. He was 10 at the time and about to travel by ship with his family to Israel. "A week later, his mother told me Eddie had won the bridge tournament on the ship going over."
By the age of 12, she recalls, he was writing lengthy letters to The Sun, opposing the war in Vietnam. "They printed many of them," Mrs. Klavens says. "I don't think they knew how young he was."
In both age and intellectual ability, there was always a gap between Edward Witten and his classmates. And it created some problems. Richard Kravitz, a classmate from the Park School, remembers his first impressions of Edward in the ninth grade.
"He was two years younger than anyone else and at least 2,000 years smarter than anybody else -- and that makes for an awkward time of it," says Dr. Kravitz, now a psychiatrist at the Yale School of Medicine. "And Ed was an awkward kid. Socially awkward, physically awkward. He was a gangly kid with terrible allergies who wore these dark-rimmed glasses. And this was tough. That kind of kid could get just destroyed, even in a place like Park School where individuality is respected."
But that didn't happen. Instead, Edward found a group that accepted him for who he was, classmates who shared his interests in academic pursuits and political events. Even now, when asked to recall their impressions, his friends and teachers paint a remarkably consistent portrait of the adolescent Edward. Brilliant, of course, but also ethical, kind, gentle, politically informed, a person of honor and decency. And it quickly became apparent that he was not just a math and physics prodigy. History, literature, writing, politics: He excelled in all of them.
The one thing he didn't excel in was athletics. Kenneth Greif, who taught young Witten English at Park School, also served as class adviser. He remembers the only piece of advice he ever gave to Edward. "I advised him not to concentrate on baseball," recalls Mr. Greif, who was singled out by his former student as an inspirational teacher. "Because I was the baseball coach too, and I was concerned. He wasn't the best athlete. . . . So I put him way in the outfield. I didn't want the ball to hit him in the head."
Ethel Klavens recalls her nephew's frustration about his lack of athletic ability. "He always wanted to be on the team and he was always the last one to be picked," she says. Later, of course, that order would be reversed: in physics and math, Edward Witten is usually among the first to be picked. Since the age of 30 he has won many prestigious awards, including the Einstein Medal, the Dirac Medal and the Fields Medal, considered by many to be the equivalent of a Nobel Prize in mathematics.
His two younger brothers and a sister have also accomplished a great deal. One brother is a lawyer, the other a playwright. His sister is a physician who also holds a doctorate in math.
The roads not taken
Despite his obvious brilliance in math and physics, say his
former teachers and friends, it was not a foregone conclusion that science was the intellectual path Edward Witten would choose.
History and current world affairs were at least as interesting to the adolescent Edward Witten as math and science, says his former history teacher Brooks Lakin. "When he warmed up to a political subject, he could totally dominate a conversation in my class," Mr. Lakin recalls. "I would say he has a very strong personality behind a quiet exterior."
History, in fact, was the subject Edward Witten chose to pursue in undergraduate school. He graduated in 1971 from Brandeis University with a degree in history. But during his undergraduate years he also immersed himself deeply in linguistics and economics. "He was so smart he could devour whole fields in a short time," recalls Peter Baida.
Those close to him at the time sensed some ambivalence in him about his future.
"I think for some number of years he was sort of running away from physics and math," Mr. Baida says.
He even took a stab at being a political journalist; he wrote one or two articles for the Nation and the New Republic. For a six-month period during 1972 he worked as a low-level aide on George McGovern's highly unsuccessful presidential campaign.
Mr. McGovern doesn't remember him at all, which is not unusual given the number of low-level aides working at his headquarters. Still, when informed that his former aide Edward Witten now was considered by some to be the smartest man in the world, Mr. McGovern replied: "Well, he was smart enough to back McGovern in '72, and I judge everybody by that criteria."
Now, sitting in his office at the Institute for Advanced Study, Dr. Witten is asked about all these detours before he moved on to Princeton, the institution from which he obtained his doctorate in physics. These detours, by the way, didn't really slow him down. At the age of 28 he became a full professor at Princeton, and, two years later, he won one of the first so-called genius grants from the MacArthur Foundation.
His answer is characteristically understated.
"Well, there isn't much to say about all that," he says. "Regardless of any deviations it was clear I was supposed to end up in math and physics."
As for his foray into politics and political journalism, he says: "Whatever truth there is about that, I think I can safely say that I learned I didn't have . . . um . . . the sort of common sense that would translate into those areas."
He bristles at any suggestion that he is, as one magazine article described him, "a liberal Democrat."
"I'm actually, for the most part, a complete agnostic politically. My only active concern is with peace in the Middle East. But if I were interested in other issues, which I'm not apt to be, they would have been economic development in the Third World and the environment."
The question of what he does for fun comes up. He doesn't seem to understand the concept. "Well, I don't care about movies," he answers after a long silence. "I tend to play badminton once a week. Right now the children take so much time that it's hard to answer the question."
"He is very good with the children, much more tolerant than I am," says his wife, who met her husband in 1975 when both were attending a physics summer school in Les Houches, France. They have been married for 16 years and have two daughters, 14 and 10, and a son, 4. But, she says, "He is much more theoretically oriented than practically oriented. Every time he has to make a little decision, it's always a big deal to Edward."
Take, for instance, the Case of the Exercise Machine.
"He really wanted to buy an exercise machine," says Ms. Nappi, "and he wanted me to tell him which exercise machine to buy. I said, 'Go to a shop and see what they have, then figure out what is the best thing for you.' And that is an impossible task for him."
The problem, which went on for "years," was finally solved when Ms. Nappi's doctor suggested she needed an exercise machine. "He wrote the name down and gave it to me. I gave it to Ed, and he rushed out to buy that exercise machine."
'Theory of Everything'
Over the past 15 years Edward Witten's work has electrified mathematicians and particle physicists. His work in string theory (sometimes called superstring theory) has been hailed by some as the most revolutionary and exciting idea in physics in more than half a century, one that could represent the ultimate goal of physics: a theory that explains all the forces of nature.
In the mid-1980s his ideas and papers prompted talk of a so-called "Theory of Everything," a term that many physicists, including Dr. Witten, dislike and consider misleading. Still, the pursuit of such a theory -- one that seeks to explain all of nature in terms of one unified field of gravity and electromagnetism -- began more or less with Einstein, who tried but failed to develop one. For many theorists, the search for the Theory of Everything remains an obsession.
In string theory, the universe is no longer made up of elementary particles, as previously held, but of tiny strings that wriggle about in 10 dimensions. Depending on how the strings are vibrating and rotating, they can represent any of the known particles of matter, from electrons to quarks. The string theorists believe that all matter and energy in the universe, all planets, all people, snowplows, vacuum cleaners, cats, dogs, the ink in this paper and everything else result from the actions and interactions of these infinitesimal bits of energy.
In other words: Superstring theory seems like a good candidate for the Theory of Everything.
Although string theory did not originate with Dr. Witten, he was one of the few physicists in the mid-1970s and early 1980s to take it seriously. And because of his reputation, once Edward Witten got interested in string theory, he gave it the credibility that was needed. He'd first learned of string theory in 1975 but was unable to understand it -- an admission that should give hope to struggling math students everywhere.
"The literature was rather impenetrable," is the understated way Dr. Witten now describes the enormous complexity of the mathematics required for string theory.
But in 1982, a review paper by John H. Schwarz of the California Institute of Technology and Michael B. Green of Queen Mary College of the University of London -- two physicists whose work he had been following -- helped Dr. Witten understand a crucial element in string theory, one that has stood in the way of providing a unified picture of gravity and quantum mechanics. What the Schwarz and Green review paper helped him grasp was this: that string theory does not simply allow for the possibility of gravity; it requires it.
"It was a long process of struggling to read that review paper, but it was so much more accessible than the previous literature I'd been reading," says Dr. Witten. "And learning how people have been able to show that string theory predicts the existence of gravity whereas standard quantum theories make gravity impossible -- that's a very striking prediction."
He stops, then starts again, casually tacking onto his statement an appraisal of the impact that "striking prediction" had on him. "In general, it may have been one of the most thrilling intellectual insights of my life. And it influenced me because it did show something about what the future of theoretical physics should be."
Still, there were problems with string theory, problems of mathematical inconsistencies. By 1984, however, there was enough evidence to demonstrate that such inconsistencies could be eliminated in string theory. It was the final step in Dr. Witten's conversion. Pronouncing it "my life's calling," he began to concentrate on the theory he says "will dominate physics for the next 50 years."
Where's the proof?
But even with the final tying together of the subatomic forces with gravity, string theory has its doubters and skeptics.
Partly this has to do with the extreme difficulty of the mathematical framework underlying the theory.
"Much of his recent work has been mathematical," says renowned Harvard physicist Sidney Coleman. "And a lot of the math stuff Ed has done in the last 10 years is just beyond me. I wouldn't know a Donaldson invariant if it hit me in the head."
Another criticism is that string theory is only a theory; it has no experimental evidence to back it up. At the moment there is no particle accelerator that comes even close to being able to experimentally test the energies and distance scales involved in string theory. Some say it may never be possible to experimentally test this theory.
Such skepticism is of no concern to Dr. Witten. "Oh, I kind of chuckle at that kind of thing," he says. "There were loads of people who predicted in the '30s you could never find gravity waves, you could never find black holes or neutron stars or neutrinos -- just to mention a few. They were all considered science fiction. I think it's very shortsighted when people make such statements."
He smiles. "Some people are disappointed that the problems haven't all been solved already. What they have trouble understanding about string theory is that it really is a level of understanding of nature that's completely different from what's existed in the past. String theory has magical properties that we're far from really understanding."
He stops, thinks of a way to convey exactly what he means: "One of the leading Italian string theorists was said to have said that string theory was a piece of 21st-century physics that fell by chance into the 20th century. And that's always been my position."
Still, he says he has not always been so certain of his own judgments. "I think one of the hardest things is to have confidence in your judgment about what's important. It's often happened to me that what I thought was really exciting wasn't necessarily considered really exciting by the people around me. Especially in the early stage of my career. But I have learned the hard way over the years that I have my judgments about what's significant in physics. And I've found out over the years that it's best to trust them."
'A basic purity'
What emerges finally from the circle of family and friends and those who know Edward Witten is this:
He is a man both loved and respected. Part of the respect, of course, is linked to his singular accomplishments. But another part is linked to something deeper: to the uncompromised, almost childlike response to life that still exists in him.
"There is a basic purity about this person," says his former teacher Kenneth Greif. "A kind of gentility and sweet simplicity about him that is very endearing."
One senses that those who know and care about Edward Witten are protective of him. Not of the theoretical physicist but of the endearing person who still wants to play bridge with his Baltimore aunts, who still makes an effort to know all of his cousins' children, who still worries a lot about hurting other people's feelings.
Still, it seems appropriate to let the learned theorist, not the endearing person, have the last word. Or, in this case, words. They are: truth and beauty. He uses them to explain the rewards of his work.
"Whether you think of them yourself or learn about them as a result of the work of others, good ideas -- really good ideas -- in math and physics are just much more beautiful than what you meet in other walks of life," Dr. Witten says.
"And part of the beauty of math and physics is that they're universal. If there are other civilizations in other galaxies, they discovered the same math we discovered -- because it's true. They might organize it differently but they've discovered the