David Mills, internet’s ‘father time,’ dies at 85
David L. Mills, a computer scientist who invented the system that allows connected computers to sync their clocks, a bedrock technology relied on by the entire modern internet, died Jan. 17 at his home in Newark, Del. He was 85.
His daughter, Eileen “Leigh” Schnitzler, confirmed the death but did not provide a specific cause.
Mills spent more than three decades as a professor at the University of Delaware and was active in designing key parts of the World Wide Web in the late 1970s and 1980s. He was a lifelong contributor to open-source software, building tools that went on to be used and modified by engineers and tech companies to this day.
His dominant contribution was teaching computers how to tell the time.
In the 1970s, researchers were building out the Arpanet, an early, government-sponsoredversion of the web that connected various nodes at universities around the country. As the net grew and more machines were connected to it, the lack of a system to make sure they all had the same concept of time was beginning to cause problems.
Because there was an unpredictable time lag whenever one machine communicated with another, simply timestamping bits of code that went between computers was not good enough to keep things in order. It was a problem that had to be solved if the internet was going to be used for financial transactions, real-time communication and a million other potential applications.
As a researcher at Comsat, the company founded by the government to develop satellite communication networks, Mills had the chance to work on Arpanet, which had been built by the Defense Department’s Advanced Research Projects Agency. Mills began working on ways to sync computer time, partly because no one else was doing it, allowing him to do the project on his own terms, he told the New Yorker in 2022. In the late 1970s he invented the Network Time Protocol, known forevermore to programmers as NTP.
Part of Mills’s insight was to build a system that ranked various computers in a network by how reliable their concept of time is. Computers connected directly to an atomic clock are deemed the most reliable, and other machines in the network rapidly communicate with each other to determine a consensus on what time it is, through a mix of complicated math and clever programming.
“I remember being totally astonished,” Vint Cerf, a computer scientist who helped lead the development of the early internet and a close collaborator with Mills, said in an interview. “It was black magic.”
David Lennox Mills was born in Oakland, Calif., on June 3, 1938. His father was an engineer, founding a company that built oil seals for car engines, according to the New Yorker.
The younger Mills was born with glaucoma, had poor eyesight for much of his adult life and went blind in the years before his death. Cerf remembered Mills using a telescope to look at whiteboards. “He was not shy about the fact that he had a vision impairment,” Cerf said. “A very down-toearth, cards-on-the-table kind of guy.”