Edward Fredkin, MIT professor and Project MAC luminary, dies at 88

Edward Fredkin, MIT Professor and former Director of Project MAC.

Edward Fredkin, MIT Professor and former Director of Project MAC, died on June 13. The computer science innovator was 88 years old.

Considered a luminary by his peers, Fredkin was multi-faceted: a fighter pilot, an entrepreneur, and eventually a trailblazer in cellular automata, digital physics, and artificial intelligence. He worked as a computer programmer at Lincoln Laboratory and later as a professor in the Department of Electrical Engineering, later renamed the Department of Electrical Engineering and Computer Science (EECS). He began at Caltech and later held academic positions at Carnegie Mellon University and Boston University.

One of the early computer programmers, Fredkin served as director of Project MAC from 1971 to 1974, spearheading efforts to develop and improve computer time-sharing systems. The late professor teamed up with CSAIL professor emeritus Jack Dennis to enhance how multiple users could share a computing resource at the same time, a project originally initiated by MIT professor Fernando Corbató in 1961.

Fredkin developed the Trie data structure, which stores strings within a data set in an associative array, organizing in a tree-like format. For example, if a user wanted to find the key “g,” they would then notice the keys “ge” and “gi” as branches of the Trie. This allows users to locate specific data, improving the retrieval process. 

"Ed Fredkin was a creative genius,” says Gerald Jay Sussman ’68, PhD ’73, the Panasonic Professor of Electrical Engineering. “He had more new ideas each day than most people have in a month. I would often walk into his office when I was stuck and he would immediately spout some ideas for me to think about. Most of the ideas were not good ones, but I could come in the next day and get some new ones. And some of his ideas were spectacularly good.”

Fredkin also designed the Fredkin gate, a computational circuit that swaps the final two bits of a data set if the first bit is one. The work is a commonly used conservative logic gate in reversible computing, a field where Fredkin is considered a key contributor. He asserted that much like how the laws of physics are reversible, so too are computations, containing the same information when operating backward. Moreover, Fredkin proposed that the universe could be viewed as an expansive computational system, which led him to become an early innovator in the field of digital physics.

His work has been a cornerstone in reversible computing, artificial intelligence, and complex systems, with his contributions to computer science earning him the Dickson Prize in Science in 1984. He was also an IT consultant to large companies such as IBM, Digital, and Motorola while serving as a CEO and being on the board of directors of other corporations. Fredkin founded organizations like Digital Equipment Computer Users' Society (DECUS) and Information International, Inc.
Beyond his innovations and accolades, Fredkin is remembered for his unyielding spirit to explore the unknown. He demonstrated an innate ability to view the world through a different lens and to ask daring questions. His peers, such as Sussman, view his mentorship as a treasure.

Fredkin is survived by his wife, Joycelin, as well as their son, Richard, and his children. The family plans to celebrate his life in October.