National Institute of Standards and Technology
Department of Commerce
Served three decades as “the nation’s timekeeper,” creating a system for synchronizing time for our financial markets and computer networks, which is accessed more than 2.5 billion times a day.
If you ever have to set a watch or a clock, you probably just look at the nearest timepiece, assume it’s accurate and quickly punch those numbers in, not worrying if you are off by a minute or two. But what if you work in the financial markets, where the accuracy of a timestamp can impact the flow of millions of dollars in assets. How can they make sure that they have the correct time that is coordinated with markets across the country? Is there a definitive authority on this matter? There is, in fact, a federal employee whose job is to keep and disseminate the nation’s civilian time. His name is Dr. Judah Levine, and he works at the National Institute of Standards and Technology (NIST). His official title is NIST fellow, but to his colleagues, he is known by a much more prestigious moniker: the nation’s timekeeper.
Accurate time and frequency information is used every day for such key applications as synchronizing telecommunications networks, controlling electric power grids, enabling navigation systems, and time-stamping electronic financial transactions. Many of these crucial functions of our national infrastructure require timing accuracy to the level of one millionth to one billionth of a second. The NIST time scale, on which these applications depend, is now one of the world’s two most accurate scales.
When Dr. Levine joined NIST almost 40 years ago, the available timing references were not accurate enough to meet the most demanding needs of industry, commerce and research – and those needs were growing more stringent every day. Levine set out to design and build a time scale that has now evolved to comprise nine atomic clocks and a complex measurement system to meet precision timing requirements.
The time scale is calibrated by the NIST-F1 atomic clock, the most accurate clock in the world, which would neither gain nor lose more than one second in 80 million years.
To ensure that NIST’s constituents in government, industry and the scientific community have convenient and reliable access to NIST time, Dr. Levine designed and operated the world's most innovative time and frequency services. In the early days of computer networks, he recognized that their synchronization over many thousands of miles would be necessary for data exchange, time-stamping and control of extensive scientific experiments such as arrays of telescopes and large particle accelerators. These applications require timing of one thousandth to one millionth of a second. But in the 1980s, no reliable and convenient system to do so was available.
In 1988, Dr. Levine invented the Automated Computer Time Service (ACTS), which uses modems and telephone networks to accurately synchronize computer clocks to official NIST time. Because the signals must travel many thousands of miles through unpredictable and changing network paths, Levine developed a clever method to determine “on the fly” the time taken for each signal to reach its target, thus ensuring computer clocks could be accurately synchronized regardless of distance.
In 1993, in the early stages of the Internet, Levine developed the Internet Time Service (ITS) to synchronize computers and Internet devices to NIST time. When ITS usage first surpassed 1 million accesses per day in 1997, it was considered a remarkable milestone. Today it exceeds 2.5 billion per day with no end of growth in sight. Levine’s ITS is now built into all major computer operating systems, such as Windows, Macintosh, and commercial Linux systems. And most routers– he traffic cops of the internet–also rely on ITS.
So the next time you’re wondering what time it is and you get an answer by looking at the bottom right hand corner of your computer, remember to thank Dr. Judah Levine for keeping you on time by keeping the nation’s time.