Bob Kahn

He was born in Brooklyn two days before Christmas in 1938, to Lawrence Kahn and Beatrice Tashker, and through his father he is related to Herman Kahn, the strategist who made a career out of thinking about nuclear war. He took an electrical engineering degree at City College in 1960 and went to Princeton, where Bede Liu supervised a doctorate finished in 1964 on the sampling and modulation of signals — the mathematics of getting something through a channel without wrecking it on the way. He went to Bell Labs, then to a faculty post at MIT, then took leave to work at a Cambridge consulting firm called Bolt Beranek and Newman. He stayed in the network business for the next 60 years.

At BBN he was the principal designer of the ARPANET, and in the autumn of 1972 he put 20 different computers in one Washington conference hall and made them talk to each other in public — the demonstration that convinced doubters packet switching was real. Then he moved to DARPA with a harder problem. The ARPANET's protocol assumed a single network. Kahn wanted many networks, built by different people out of different hardware, to behave as one. He set the ground rules: a specialised machine at each border doing nothing but forwarding packets, no part able to control or kill the whole, every packet numbered and checksummed, every arrival acknowledged, anything unacknowledged sent again. Vint Cerf joined him in the spring of 1973. What they wrote became TCP, then TCP and IP, and it is still the arrangement.

All of it was Pentagon money, and Kahn ran the office that spent it. In 1983 he launched the Strategic Computing Initiative, a billion Defense Department dollars over ten years aimed at machine intelligence for war — a vehicle that drove itself, an aircraft that advised its pilot, a machine that would see and hear and think. It did not get there. A successor at DARPA cut the artificial intelligence work, in the historian Pamela McCorduck's phrase, deeply and brutally. What survived was the autonomous vehicle research that self-driving cars now rest on. The credit is unsettled too. Packet switching had been worked out independently by Paul Baran and Donald Davies before either Kahn or Cerf touched it, and calling the two of them the fathers of the internet has never sat well with everyone who was in the room.

He left DARPA in 1986 and started the Corporation for National Research Initiatives, and has run it ever since. The second career is quieter and touches anyone reading a footnote: the Handle System he built there, running from 1994, sits under the digital object identifier, so every doi resolves through his design. In September 2000 he and Cerf defended Al Gore, then being mocked over a remark about the internet: no one in public life, they wrote, had done more to create the conditions for it. The honours came steadily: a Turing Award in 2004, the Presidential Medal of Freedom in 2005, the IEEE Medal of Honor in 2024. Of the two names on TCP, his stayed out of view.

Bob Kahn's life against the full span of the corpus — the fading end marks a life still in progress.

• ARPANET invention
  Principal designer of the network at Bolt Beranek and Newman 1969
• A Protocol for Packet Network Intercommunication article
  The Cerf and Kahn paper that set out TCP 1974
• Strategic Computing Initiative mission
  A billion Defense Department dollars aimed at machine intelligence 1983
• Corporation for National Research Initiatives company
  The nonprofit he has chaired since leaving DARPA 1986
• Internet Society company
  Co-founded with Vint Cerf 1992
• Handle System invention
  The resolution layer beneath the digital object identifier 1994

• 1960 aged ~22 Takes an electrical engineering degree at City College of New York
• 1964 aged ~26 Finishes a Princeton doctorate on the sampling and modulation of signals Supervised by Bede Liu.
• 1969 aged ~31 Serves as principal designer of the ARPANET at BBN
• Autumn 1972 aged ~34 Connects 20 computers in public at the conference in Washington The demonstration that made packet switching credible outside the laboratory.
• Spring 1973 aged ~35 Vint Cerf joins him and they draft the first version of TCP
• 1983 aged ~45 Launches the billion-dollar Strategic Computing Initiative at DARPA The largest computing research program the federal government had run.
• 1986 aged ~48 Leaves DARPA and founds CNRI in Reston, Virginia
• September 2000 aged 61 Publishes a defence of Al Gore's record on internet funding with Cerf
• 2004 aged ~66 Shares the Turing Award with Vint Cerf The Presidential Medal of Freedom followed in 2005 and the IEEE Medal of Honor in 2024.

• Vint Cerf b. 1943
  Co-designer of the TCP/IP protocols that form the foundation of the internet. co-invented TCP/IP with
• Tim Berners-Lee b. 1955
  British-American computer scientist who invented the World Wide Web, revolutionizing global information sharing. built the Web on his protocols
• Al Gore b. 1948
  Vice president and 2000 presidential candidate who became a leading advocate for climate policy. defended in print
• Robert Metcalfe b. 1946
  Co-invented Ethernet at Xerox PARC and founded 3Com to commercialize local area networking. built the local network under his
• Douglas Engelbart 1925–2013
  Engineer who invented the computer mouse and demonstrated interactive computing in 1968. ran an early ARPANET node