The Man Who Wired the World: Robert Metcalfe and Connectivity

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Laureates of mathematics and computer science meet the next generation
Heidelberg Laureate Forum

The 10th Heidelberg Laureate Forum kicked off with a captivating lecture by Robert Metcalfe, the 2022 ACM A.M. Turing Award recipient and the inventor of Ethernet. In his engaging style, Metcalfe took the audience on a journey through the past, present, and future of connectivity.

Robert Melcanton Metcalfe, speaking at 10th Heidelberg Laureate Forum (Image credit: Heidelberg Laureate Forum Foundation)

Connecting the world

Global connectivity has come a long way in the past couple of decades. It can be hard to imagine as you read this on your smartphone or laptop, connected to a 4G or 5G network, but there was a time, not that long ago, when the internet and high speed data transfer seemed like a pipe dream. In our modern times, we are just a few clicks away from most of human knowledge, and we can reach our friends and family in text, audio, or video. But we should not take the openness of the internet for granted.

In fact, Metcalfe says, the story of global connectivity begins with monopolies. To get an idea of how connectivity used to work in his youth, Metcalfe humorously recalls what his mother told him when he left for college. “When you get to Boston, Bobby, call us to let us know you’re okay. We’ll let it ring three times to know you’re okay.” Beyond the humorous intent lies an important point: In that time, even the cost of a phone call was significant. Metcalfe is one of the people that changed that and brought us to where we are today.

However, his path was rarely straightforward.

His first advisor, Marvin Minsky (also a laureate in computer science), did not like his initial work. Metcalfe had to change paths, and eventually started work on computer connectivity, where his work would go on to change the world.

Metcalfe recalled how in the early stages of his work, he was confronted with a problem. Inventors wanted to put “a computer on every desk.” It seemed outrageous at the time. But for Metcalfe, the problem was how to get these computers to “talk” to each other and exchange information in a practical way.

He would go on to invent and develop Ethernet technology. Yet, the journey to Ethernet’s success also had its share of complexities.

Aloha, Ethernet

Ethernet is a foundational technology for local area networks (LANs) that enables devices within the same physical location to communicate with each other. Ethernet provides a set of protocols and standards for how data packets should be placed on the network and transported between computers, employing a combination of hardware and software to facilitate fast, reliable data transfers. Ethernet laid the groundwork for modern networking and has had a transformative impact on everything from education and technology to healthcare. It enabled the advent of the World Wide Web, dial-up internet, and eventually, broadband.

Before all that, though, there was ALOHAnet.

ALOHAnet, short for “Additive Links On-line Hawaii Area,” was an experimental wireless network created at the University of Hawaii. It became operational in 1971. In its purest form, ALOHAnet used remote units communicated with a base station over two separate radio frequencies (for inbound and outbound transmission respectively). It was the first public demonstration of a wireless packet data network.

Metcalfe was looking for a way to have PCs take turns communicating on a shared cable in Ethernet. He learned that radio (which ALOHA used) is not a suitable technology for a local area network, but he did use the ALOHA random-access techniques and he incorporated them in Ethernet.

Other technical innovations, like replacing the original coaxial cable with a flexible cable gradually made Ethernet more appealing. In 1976, when Metcalfe published a seminal paper discussing the advantages and potential of Ethernet, the protocol was already functional.

But for a time, it was not clear whether Ethernet would become the dominant protocol.

The LAN Wars

The creation of Ethernet was an innovative leap in packet-mode communication. But it was not the only competing protocol.

Other tech companies developed their own protocols as well. “But we won,” recalls Metcalfe.

Ethernet became established for several reasons: “For starters, it worked,” says Metcalfe – which is a pretty important part of why things become popular. Specifically, it was fast. Ethernet offered speeds that were approximately 10,000 times faster than its predecessors, dramatically outperforming competing protocols in both speed and reliability.

It was also open. Ethernet is an open standard, which spurred innovation and collaboration. It is only fitting that the most common standard for computer connectivity also favors human connectivity.

As computers and the internet have changed, Ethernet has managed to keep up the pace. For instance, video accounts for over 80% of the internet traffic and the protocol was never designed to work with this type of load. Nevertheless, subsequent updates and improvements have helped Ethernet keep up with the changes.

Pathologies, Potential, and Metcalfe’s Law

An interesting segment of Metcalfe’s talk was devoted to Metcalfe’s Law, which states that the value of a network increases proportionally with the square of the number of connected users. In simple terms, the more people and devices that are connected, the more valuable the network becomes. This insight has implications far beyond computing, affecting social networks, online marketplaces, and even political movements.

Though optimistic about the potential of universal connectivity, Metcalfe did not shy away from addressing its challenges. These include issues related to disinformation, security, and even hacking. The internet has faced various “pathologies,” as Metcalfe calls them, but the laureate is confident that while technology can create these problems, it can also be instrumental in solving them. Metcalfe seems optimistic about the future of connectivity, even mentioning the Voyager spacecraft as an extreme example of how far connectivity has come.

It was a fitting start to the HLF. Metcalfe is best known as the inventor of the Ethernet technology, but his own path is a testament to connectivity between different worlds. Throughout his career, Metcalfe has been an academic, inventor, entrepreneur, and pundit. His path has shown how these different worlds can be connected through our actions. Of course, connectivity also lies at the core of the HLF. This event is all about the connections we make here.

As the audience left the auditorium, it was clear that Metcalfe’s words had struck a chord. The room was buzzing with talk of past innovations and future possibilities. It was a powerful reminder that connectivity is not just about hardware and software; it is about human relationships and how they shape our world.

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Andrei is a science communicator and a PhD candidate in geophysics. He is the co-founder of ZME Science, where he published over 2,000 articles. Andrei tries to blend two things he loves (science and good stories) to make the world a better place -- one article at a time.


  1. Andrei Mihai wrote (28. Sep 2023):
    > […] Metcalfe’s Law, which states that the value of a network increases proportionally with the square of the number of connected users.

    Metcalfe’s Law, as stated, can however be supplemented by certain caveats; especially

    The value of a network of users who all mutually benefit from being connected to each other increases proportionally with the square of the number of those users.

  2. In practice, Metcalfe’s law means the following: Twice as many users mean 4 times as many connections, provided that each user is connected to each other. From a financial point of view, this means: The costs grow linearly with the number of users, but the connections grow squarely with the number of users.

    In the end, Metcalfe’s law says something about the profitability of networking. In fact, Robert Metcalfe was not only a scientist and technician, but also a gifted marketer. In the German-language Wikipedia one reads:

    He successfully convinced the companies DEC, Intel and Xerox to work with him to make Ethernet the standard. At that time, competing techniques were the proprietary systems Token Ring and ARCNET, both of which soon sunk into a true flood of Ethernet products. 3Com became a large company.

    • Müsste dull sein, wie bringen Sie so-o nur bei ? :
      -> Twice as many users mean 4 times as many connections, provided that each user is connected to each other. From a financial point of view, this means: The costs grow linearly with the number of users, but the connections grow squarely with the number of users.’

      Schämen Sie sich.

      Mit freundlichen Grüßen
      Dr. Webbaer (der im Abgang, neugierig geworden, auch gerne so anfragt :
      -> )

  3. Der Gag besteht sozusagen darin, dass ein wie hier angelegtes Protokoll warten kann, anders als seriell angelegte Protokolle; geschaut werden kann auch so :

    -> ‘In der Praxis funktioniert dieser Algorithmus bildlich wie eine Diskussionsrunde ohne Moderator, auf der alle Gäste ein gemeinsames Medium (die Luft) benutzen, um miteinander zu sprechen. Bevor sie zu sprechen beginnen, warten sie höflich darauf, dass der andere Gast zu reden aufgehört hat. Wenn zwei Gäste zur gleichen Zeit zu sprechen beginnen, stoppen beide und warten für eine kurze, zufällige Zeitspanne, bevor sie einen neuen Anlauf wagen.’ [Quelle]

    Sicherlich erst im sogenannten LAN (“local area network”) getestet, geübt, statt zuvor seriellles, Austauschverfahren meinend, ein sogenanntes asynchrones Medienzugriffsverfahren lag erstmals vor.

    Mit freundlichen Grüßen
    Dr. Webbaer

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