As a distinguished IEEE Life Fellow and leader within STEM education, Gerald Jay Sussman has developed valuable approaches and methods for teaching computer science. Sussman is the Panasonic Professor of Electrical Engineering at the Massachusetts Institute of Technology (M.I.T.), where he also received his S.B. and Ph.D. degrees in mathematics. From contributing to M.I.T.’s AI research endeavors since 1964 to pioneering collaborations with luminaries like Richard Stallman and Guy L. Steele Jr., Sussman has played a key role in almost 50 graduate students’ journeys. On top of that, his landmark textbook, “Structure and Interpretation of Computer Programs,” was used within M.I.T.’s curriculum for over two decades. Additionally, Sussman’s impact transcends conventional boundaries, extending into realms of astrophysics, computer-aided design, and more.
In honor of his many achievements, he has received the 2024 Taylor L. Booth Education Award for, “… providing a novel, long-lasting, and inspirational approach to the teaching of computer science through functional programming that has impacted students from a broad range of STEM disciplines.“
As a Life Fellow of IEEE and a member of many accomplishments, what milestones within your journey are you most proud of, and what major connections have you made along the way?
I am most proud of the fact that my work has contributed to the education (not training) of many students, at all levels. Through my classes, I have influenced the thinking styles of thousands of undergraduates. I have been the PhD thesis supervisor of almost 50 wonderful graduate students. Many of them have become fine teachers. And ideas from my books have influenced some high-school curricula.
I regularly get emails from former students and other readers telling me that although they did not quite realize the importance at the time, my classes and my writings have had a major influence on their lives. That makes me feel very good.
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You and your former student Guy L. Steele Jr. invented the Scheme programming language in 1975. How has the concept of the Scheme programming language impacted the field of computing? What were the main principles behind it, and how do you see its relevance in today’s computing landscape?
I do not think that the impact of Scheme has sunk into the culture of computing even now. People make elaborate languages that provide shortcuts and “conveniences” that tend to hide the ideas in their programs, rather than expose them. The essential idea is best captured by the introductory paragraph of the foreword to the IEEE Standard for the Scheme Programming Language:
“Programming languages should be designed not by piling feature on top of feature, but by removing the weaknesses and restrictions that make additional features appear necessary. The Scheme programming language demonstrates that a very small number of rules for forming expressions, with few restrictions on how they are composed, suffice to form a practical and efficient programming language that is flexible enough to support most of the major programming paradigms in use today.”
How did you approach teaching fundamental concepts using Scheme, and what insights did you gain from this experience?
The use of a very simple language, with little syntax but powerful means of combination and abstraction, allows me to express and illustrate important ideas, avoiding the intellectual clutter of complex syntax and complicated mechanisms. The simplicity of Scheme allows exposure of the essence of computation, without the accidental distractions of most languages. As Alan Perlis quipped, “Syntactic sugar causes cancer of the semicolon.”
Can you elaborate on your collaboration with Jack Wisdom and the Digital Orrery? Additionally, please explain the significance of discovering numerical evidence for chaotic motions in the outer planets.
In 1983-1984 I was on sabbatical leave from MIT. I was hanging out in the Caltech Theoretical Astrophysics group. Jack Wisdom was a student of Peter Goldreich in that group. Jack’s PhD thesis accounted for the 3:1 Kirkwood gap in the asteroid belt by discovering chaotic motion of any asteroids that might have been in that gap. But Jack used a novel mapping instead of a more traditional integrator for the equations of motion. I wanted to test his theory with traditional integration. But such an integration was infeasible with currently available computers. So I designed and built the Digital Orrery, a special-purpose computer for doing high-precision long-term orbital mechanics calculations. (I had lots of help from friends at Caltech and friends at Hewlett-Packard.)
When I returned to MIT Jack was a new faculty member in our Earth, Atmospheric, and Planetary Sciences Department. So we collaborated using the Digital Orrery to do some exciting computations. The most important was the discovery of the chaotic motion of Pluto. The underlying problem is whether the Solar System is stable. The three-body problem was already hard enough to stymie Newton. Poincare showed that most solar systems are unstable, but our solar system could not be shown to be unstable by his calculations. Later, Kolomogorov, Arnold, and Moser showed that there are stable solar systems, but ours could not be shown to be stable by their methods. Our computations showed that our solar system’s stability is marginal at best: small variations in the initial conditions lead to very different future configurations. So this was a major step in the resolution of the issue.
Throughout your career, you’ve ventured into diverse fields ranging from Artificial Intelligence to Astrophysics. What advice would you give to early-career researchers and educators who aspire to pursue interdisciplinary paths like yours?
My advice is “Figure out what you will enjoy doing and do it!” It is important that when you get up in the morning you are happy to start working — it had better not be a chore. If you are doing what you want to do you will do a good job and others will appreciate it. Do not let yourself be pressured to do something you do not want to do just because it is “trendy” and likely to be strongly rewarded. Life is short, so have fun.
More About Gerald Jay Sussman
Gerald Jay Sussman is the Panasonic (formerly Matsushita) Professor of Electrical Engineering at the Massachusetts Institute of Technology (M.I.T.). He received the S.B. and the Ph.D. degrees in mathematics from M.I.T. in 1968 and 1973, respectively, and joined the faculty in 1973. He has worked in Artificial Intelligence research at M.I.T. since 1964.
Sussman is a Life Fellow of the Institute of Electrical and Electronics Engineers (IEEE). He is a member of the National Academy of Engineering (NAE), a fellow of the American Academy of Arts and Sciences, a fellow of the American Association for the Advancement of Science (AAAS), a fellow of the Association for the Advancement of Artificial Intelligence (AAAI), a fellow of the Association for Computing Machinery (ACM), and a fellow of the New York Academy of Sciences (NYAS). Sussman is a founding director of the Free Software Foundation. He has been a bonded locksmith. He is a member of the American Watchmakers-Clockmakers Institute, the Massachusetts Watchmakers-Clockmakers Association, the Amateur Telescope Makers of Boston, and the American Radio Relay League.
