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Professor Emeritus Paul Penfield, chronicler of entropy and lifelong teacher, dies at 88

A former department head who established the MEng degree for EECS undergraduates, Penfield developed courses illuminating the equivalence of information and thermodynamic entropy.
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Headshot of an older man who is smiling slightly at the camera
Professor Emeritus Paul Penfield, shown here in his formal MIT portrait
Photo: Department of Electrical Engineering and Computer Science

Paul Penfield, the Dugald C. Jackson Professor of Electrical Engineering, Emeritus, died on June 22 at age 88. Affiliated with the Microsystems Technology Laboratories (MTL), Penfield was a member of the MIT Department of Electrical Engineering and Computer Science (EECS) faculty for 45 years, beginning in 1960. He served as associate head of the department from 1974-78; as director of the Microsystems Research Program from 1985-89; and as department head from 1989 to 1999.

He was the Dugald C. Jackson Professor of Electrical Engineering from January 2000 until his retirement in June 2005. In 1996-1997 he served as president of the National Electrical Engineering Department Heads Association (NEEDHA) and in March 2000 received its Outstanding Service Award. In 1998 he organized the Building 20 Commemoration, for which he received the 1999 Presidential Citation from The Association of Alumni and Alumnae of MIT.

As a departmental leader, Penfield was instrumental in building up MIT EECS’s activity in silicon integrated circuits. He played a key role in bringing Lynn Conway, as a visiting professor, to EECS in 1978 to teach the first very large-scale integration system design course, culminating with student-designed integrated circuits that were fabricated by HP. This launched not only a universally-accepted syllabus, but also the concept of the MOSIS foundry. As associate head of the EECS department, and subsequently founding director of the Microsystems Research Program, he also spearheaded the establishment of the MTL, which allowed MIT to reclaim a prominent national position in silicon technology. As associate head of EECS, he built faculty strength not just in integrated circuits, but in the computer architecture that this field of study enabled. 

One of Penfield’s most significant contributions to the EECS community was the development of 6.050J / 2.110J (Information, Entropy, and Computation), a course offered jointly by EECS and the Department of Mechanical Engineering for almost 20 years, which helped make the Second Law of Thermodynamics more accessible to first-year students by treating entropy as a form of information. Penfield cared deeply about education in electrical engineering and computer science, articulating the importance of both “The Electron and the Bit” in the past and future evolution of the field. His devotion to his students was fittingly commemorated with the Paul L. Penfield Student Service Award, granted to undergraduate, MEng, and graduate students alike to honor his devotion to the department. Another lasting contribution was Penfield’s establishment of the master's of engineering degree as an accessible and primary path for MIT EECS undergraduates, following (or integrated with) their bachelor’s degree.

Beyond the classroom, Penfield’s wide-ranging research interests included inquiry into solid-state microwave devices and circuits, noise, and thermodynamics; electrodynamics of moving media; circuit theory; computer-aided design; APL language extensions; integrated-circuit design automation; computer-aided fabrication of integrated circuits; and the equivalence of information and thermodynamic entropy. His meaningful contributions to the field, including five books and hundreds of papers, were recognized with the Centennial Medal from IEEE in 1984, the IEEE Circuits and Systems Society Darlington Prize Paper Award in 1985, and the IEEE Circuits and Systems Society Golden Jubilee Award in 1999. Penfield was a fellow of the Institute of Electrical and Electronics Engineers (IEEE) and the International Engineering Consortium; a member of the National Academy of Engineering, Sigma Xi, the American Physical Society, the Association for Computing Machinery, the Audio Engineering Society, and the National Electrical Engineering Department Heads Association.

A passionate environmentalist and member of the American Fern Society and the Hardy Fern Foundation, Penfield cultivated a collection of ferns, beginning with spores in petri dishes and planting the larger specimens in the garden around his home. In the weeks immediately preceding his death, friends found him busily engaged with the installation of a QR-code-based system of plant identification placards for his home town of Weston, Massachusetts.

“For me, dad was through-and-through a professor,” says his son, David Penfield. “Knowledge was his currency of life … His goal was to become an expert — not for fame, fortune, to one-up people, or to belittle people. Rather, he wanted to be an expert because he realized it was the best way to contribute to a project, to others’ well-being, and to make the world a better place.”

One of Penfield's most notable contributions to that better world was his tireless championship of the development of an ecologically sound rail trail in Weston, where residents and visitors could hike and ride bikes in peaceful, wooded surroundings.

Penfield’s devotion to his community was exceeded only by his dedication to his family, whose growth and successes he chronicled with pride as an amateur genealogist. (His talent for investigation was reflected in his meticulously-researched family tree, which extended back to the 1600s.) He was predeceased by his first wife Martha Elise (Dieterle) Penfield, his second wife Barbara Jean (Buehrig Lory) Penfield, his sister Eleanor Baldwin (Penfield) Spencer and her husband Guilford Lawson Spencer II. He is survived by his companion, Catherine Liddell, of Natick, Massachusetts; his sister Martha Warren (Penfield) Brown and her husband David Tyner Brown of Virginia Beach, Virginia; three children: David Wesley Penfield and his wife Rebecca Emily Bronson of Westford, Massachusetts (sons Andrew Bronson Penfield and Scott Arthur Penfield), Patricia Penfield Jonas and her husband Craig Christopher Jonas of Lakewood, Colorado (son Paul Penfield Jonas), and Michael Baldwin Penfield of Saint Paul, Minnesota; four step-children: John Albert Lory and his wife, Joan Elaine Jouriles of Columbia, Missouri (sons Joshua Nicholas Lory and Asa John Lory), Stephen Richards Lory of Arcata, California (children Aaron Matthew Lory and Shaely Sullivan), Carol Frances (Lory) Topp of Vienna, Virginia (children Russell Francis Topp and Emilia Susan Topp), and Cameron Lory Faulds and her husband Andrew James Faulds of Brooklyn, New York.

Contributions can be made in Penfield’s memory to The Lake George Land Conservancy or The Spectrum Singers.

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