Honoring Bob Metcalfe: Turing Award Winner


In 1973, Bob Metcalfe circulated a memo describing a new type of system for networking personal computers within the Xerox Parc offices in which he worked. He was outlining what would later become a ubiquitous and powerful technology enabling modern communication and business activity: Ethernet. In recognition of his legendary career, Metcalfe has been awarded the A.M. Turing award for his contributions to “creating the foundational technology of the Internet, which supports more than five billion users and enables much of modern life.” SparkCognition celebrates this extraordinary honor for our friend and mentor, Bob Metcalfe, who joined us as a Research Fellow and Advisor in 2019. 

But in the early 1970s at Xerox PARC, Metcalfe’s employer just wanted to use their new Xerox Alto machines (a pioneering personal computer workstation featuring a graphical user interface and a mouse) to share files, transfer data, and connect to printers. Metcalfe proposed a “broadcast communication network” that could solve the highly limiting problem of traffic congestion in the early computing days—when multiple personal computers wanted to send data on the same network at the same time, collisions would occur, the channel would be unstable, and throughput would be low. 

Metcalfe had been interested in an early wireless networking program that started in the Hawaiian Islands called ALOHANET and had written his Ph.D. dissertation on packet switching network improvements related to ARPAnet (the early incarnation of the internet) and ALOHANET. At Xerox PARC, he had his chance to demonstrate how to maximally distribute a network, decentralizing the load of the system to the edges as much as possible. Working with his colleague, David Boggs, they used coaxial cables to set up a system capable of negotiating access to a shared communications channel, detecting when a collision occurred proactively (before transmitting to load the system even further), with a backoff algorithm that allowed the system to function even at 100% load. In very basic terms, he and Boggs figured out how to send data through networks reliably and at scale. An important distinction in their design is that it wasn’t dependent on coaxial cables or any specific networking medium or intended for any specific terminal machine to use: it connected the “ether,” however that may be defined. This allowed it to support later networking advancements like fiber optics and WiFi. In Metcalfe and Boggs’ 1976 paper popularizing the innovation, they explained: “An Ethernet’s shared communication facility, its Ether, is a passive broadcast medium with no central control. Coordination of access to the Ether for packet broadcasts is distributed among the contending transmitting stations using controlled statistical arbitration.“ 

In 1979, Metcalfe co-founded the highly successful company, 3Com, to commercialize Ethernet technology and was instrumental in helping to establish Ethernet and internet networking standards in the early 1980s that helped the world wide web proliferate. He is also known for originating one of the cardinal laws of the modern technology age—Metcalfe’s Law—which posits that “the value of a telecommunications network is proportional to the square of the number of connected users of the system.” This concept, along with Moore’s Law, and others, continues to inform theories of innovation and potential in the tech and telecommunications industries and can be seen at work in social networks and cryptocurrency markets today. 

It’s virtually impossible to wrap one’s head around the implications of Metcalfe’s pioneering work and the milestones of his career, but consider that right now, as you read this article digitally, you are almost assuredly using his invention. And with smart devices and IoT and rapidly advancing artificial intelligence keeping us connected 24/7—much, if not all of which still relies on Ethernet in some capacity—the global community and generations to follow owe a debt to Ethernet as a foundational technology that has facilitated progress and communication over the last 50 years.

As it was aptly written in this 2020 ComputerWeekly article: “The internet may owe Bob Kahn, Vint Cerf, and Tim Berners-Lee a great debt, but Bob Metcalfe’s Ethernet sits beneath all of them as the giant that has allowed them to see further.”

We encourage you to read or watch any of the fascinating oral history projects that Metcalfe has participated in. His personality and intelligence practically jump off the screen. Here’s a short list.


One of the anecdotes in these interviews particularly stands out. In a self-effacing way, Metcalfe described himself as feeling like something of a plumber in the works of the internet, connecting the cables and electric signals. Once, at a premiere of Steve Jobs’ Pixar’s first movie, he expressed this to Jobs. Job’s reply was that Ethernet had carried every single pixel of his movie. Plumbers don’t win A.M. Turing awards. 

Bob Metcalfe has also received the National Medal of Technology, the IEEE Medal of Honor, the IEEE Alexander Graham Bell Medal, the ACM Grace Murray Hopper Award, the Marconi Prize, the Computer History Museum Fellow Awards, and is a member of the Internet Hall of Fame.

In the words of Bruce Porter, Chief Science Officer at SparkCognition: “Professor Metcalfe’s contribution to the development of Ethernet, one of the most profound inventions in the technology world, paved the way for the innumerable applications integral to our daily lives – including artificial intelligence. We are humbled and proud by our association with him and look forward to his continued inspiration and mentorship at SparkCognition.”

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