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."