VISIT a theoretical physicist at work, and you're apt to find someone dressed in a T-shirt and running shoes. Shirley Ann Jackson, settling into a conference-room chair before a blackboard scrawled with graphs and mathematical symbols, wears a blue suit and lace-collared blouse. But she's used to being different. A specialist in condensed matter physics at Bell Labs, she is the first black woman to earn a PhD in physics in the United States. ``I had a professor tell me that colored girls should learn a trade,'' she says without rancor, recalling her undergraduate years (Class of '68) at the Massachusetts Institute of Technology, where she also earned her doctorate in 1973. ``When I would get on an elevator, people would sometimes mistake me for the elevator operator. I've been shot at, I've been spit on, I've been chased - I've had all of those things. But then, I did go to a school that was primarily male. So it wasn't always easy.''
Even today, when she goes to international meetings on physics, she reports that ``many, many times I don't see another black - and very few women.''
What has carried her through this sometimes uncongenial climate? The fact that she loves physics. ``My goal was always to pursue the physics opportunities,'' she says, ``and however great or non-great I might turn out to be, I thought it was important to be in an exciting place, to work on exciting problems.''
That excitement began, Dr. Jackson recalls, in her early years in Washington, D.C., where her father was a postal worker and her mother a social worker. A product of an almost entirely black public high school in Washington, she says she benefited by growing up in the ``post-Sputnik era'' - when the nation, jolted by the successful launch of a Soviet satellite in 1957, beefed up its science and math curriculum. ``I had a mixture of the new and old math,'' she says, referring to the controversial technique of teaching set theory to beginning students, ``and I loved it. When I was a little kid, I used to play mental mathematical games.
``But as far as science was concerned, most of my early interest had to do with biology. I used to collect live insects. I abhorred the typical collection with dead insects: I thought it was more interesting to observe the insect in his environment. ... , how he adapted. So I used to collect bumblebees, do little experiments on them, change their nutritional situation, put different kinds together. I used to keep the jars under the back porch - we had a crawl space - so you would come out onto the porch and you'd hear all the buzzing from 20 or 30 jars.''
``It was primarily self-teaching,'' she adds, noting that she gleaned her information not from courses in school but from Scientific American, encyclopedias, and city libraries. At school, she says, her two most influential teachers were in mathematics and in Latin. ``I studied Latin for six years. My original goal was to be a mathematics and classics teacher.''
As an undergraduate at MIT, she began to take an interest in physics - which, she says, ``seemed to be a good marriage of mathematics and the natural world.'' The introductory physics course caught her attention, she recalls, because ``it wasn't just learning about pulleys and strings, but about thinking physically.'' One of the first assignments was to estimate the number of blades of grass in the MIT courtyard. Though it first seemed a ``crazy'' task, it taught the class ``how to do seat-of-the-pants calculations to test your more exact calculations, and how to understand physical laws and symmetry principles.''
By graduate school, Jackson had settled on theoretical physics. She did her doctoral dissertation in high-energy physics, working at the Fermi National Accelerator Laboratory outside of Chicago and at the European Center for Nuclear Research (CERN), near Geneva. But her undergraduate work in materials sciences, where she studied low-temperature superconductors, still fascinated her. So, pursuing a second period of post-doctoral study, she got back into condensed-matter physics, joining the staff at Bell Labs in 1976.
To some extent, her shifting of fields has given her an uncommon breadth of interests - though it has not made her, she says, a real generalist. ``I think in order to make a contribution in any given subdiscipline, one has to focus and go into depth. That's how one can uncover something that's different.'' Yet science also ``requires you to be broad, because you have to see what the connections are - you have to have a context within which the research problem exists.'' Otherwise you don't have a sense of what is significant.''
She also feels it's important to ``try to contribute in ways beyond my discipline.'' A trustees of MIT and of Rutgers University, she was also appointed by Gov. Thomas H. Kean to the New Jersey Commission on Science and Technology, which promotes collaborative efforts by universities and industries.cho In addition, she says, watching her eight-year-old son become interested in mathematics has ``gotten me interested in how young people learn.''to here
So what would she tell young people about the rewards of a career in physics?
``What's so great about it is that there's something new every day,'' she says. ``What science gives you is the chance to be the one who uncovers the unknown, who creates the new paradigm. And all along the way there are all the little thrills having to do with the little discoveries you make - and there's a lot of satisfaction.''
She admits that it's hard work - in part because ``science and mathematically based disciplines are cumulative. It is very hard to jump into it if you don't have the background. But if you look at a lawyer who's successful, or a surgeon, or a writer - these people work hard at what they do, too.''
Science also requires, she adds, ``a certain time alone,'' in order ``to reflect, to research.'' Yet in involves plenty of group effort, since ``a large part of making a breakthrough in a research problem is interacting with other people.''
In her field, the cutting-edge issues for the future, she says, will include an understanding of:
Mesoscopic systems, where matter is observed at an extremely small scale. Traditionally, she says, ``physics is based on observation of bulk phenomena.'' But do the same laws apply as the dimensions shrink toward quantum lengths?
Wigner crystallization (named for physicist Eugene Wigner), which occurs when particles like electrons are squeezed together hard enough to overcome their mutual repulsion. The result, she says, is ``a stable, ordered structure - a kind of crystal.'' Squeezed even harder, the crystals experience ``a kind of quantum melting'' that could further help explain the fundamental nature of matter.
Magnetism, an old subject that is gaining new importance in the building of magnetic semiconductors and high-temperature superconductors. Understanding the relationship of magnetism and the spins of fundamental particles, she says, could have ``a dramatic effect'' on our ability to understand such things as the optical properties of matter.
Brain functions, which could help explain ``how highly complex systems organize themselves.'' Such an understanding could ``have implications in computer architecture.''
``These are the sorts of things that at least interest me,'' she says. And for avocations? Childrearing (she has an eight-year-old son) and piano lessons. ``I decided a few years ago,'' she says with the confidence of a woman who seems right at home mastering new fields, ``that I had always wanted to play the piano.''