with tortoise

Demetrios Matsakis is Chief Scientist of the Time Service Department at the U.S. Naval Observatory (USNO), keeper of the official Master Clock not only of the Department of Defense but for all of America as well.

Time is disseminated from the USNO Master Clock is the official time in America and, through GPS, the de-facto source of time for the entire world.

The USNO Master Clock is a system of over 100 clocks, three different types of ultra-precise clocks.

“I refer the clocks as my babies — my job is to take care of them,” Demetrios says. A watchful eye is kept on temperatures; temperature fluctuations change how clocks keep time. Vibrations also can cause problems; the clocks are on mounted stabilizing platforms that insulate from vibrations.

Once something that looked like mud was found near one of the clocks. At first they thought it was coffee but it turned out to be merely condensation. “We were lucky it wasn’t coffee — the caffeine could have caused the clocks to speed up,” Demetrios joked.

The clocks measure time in frequencies to 16 decimal points — so accurate that not a single second will be gained or lost in 300 million years. It is the most accurate 24/7 measuring system ever created by mankind, although the USNO and others continue building more accurate clocks.

Precision is important. If a GPS satellite is off by one nanosecond (one billionth of a second), the GPS receiver (your car) will be off course by two to three feet.

Demetrios says, “I like to tell people I don’t know exactly what time is but I can tell them exactly what a second is. A second is 9,192,631,770 periods of the undisturbed cesium atom, now only indirectly referenced to the geoid [sea level], because the geoid isn’t well enough defined.”

Demetrios holds a BS Physics from MIT, a PhD Physics from the University of California, has authored over 100 publications, negotiated agreements with other countries, and received many awards. In September 2015 he organized an international conference in Paris to discuss the best ways for nations to combine their data for maximum precision and accuracy and avoid redundancy.

He was an Eagle Boy Scout in St. Louis, his hometown. In his younger days he studied alcohol and ammonia in the nebulas where stars are born and quasars near the edge of the universe are observable.

While timekeeping is his job, the history of it is Demetrios’s hobby. He has a grandfather clock in his office.

He points out a perk of the job: because he’s surrounded by clocks, there’s no need to wear a watch. But he never wore one anyway because he’s never wanted the measurement of time to define the experience of time.


“Time is a wonderful invention. It’s what keeps everything from happening all at once.”


Walking into library

Matsakis from Washingtonian

me in front of antenna 1 mb