Dr. Nadya Goldovsky is the keeper of time in Israel. She is officially head of the Laboratory of Frequency and Time of the National Physical Laboratory of Israel, located at the Coordinated Universal Time Laboratory at Hebrew University on Givat Ram in Jerusalem. Dr. Goldovsky is in charge of keeping exact time, not just in minutes and seconds, but in even more precise units.
She works for the Israel Economy Ministry, which holds the standard for all physical units, according to international standards. In 1992, for legal purposes, the Knesset passed The Law Determining the Time, which made the National Physical Laboratory in the Industry and Trade Ministry set the standard for an accepted basis of time in the world.
Controlling time also affects global politics and governmental issues. Russia and the U.S. each have competing time systems and Europeans are in the process of creating their own system so they won’t have to be reliant on either country.
So how does Dr. Goldovsky control time? She explains: “In the past we would measure the time according to the rotation of the earth. You would take the day and divide it into 24 hours, then divide the hour into 60 minutes, and the minute into 60 seconds, and that is how you reached a single second. But since then it’s been discovered that the earth’s rotation is not stable and not very precise, but with a deviation of milliseconds. Therefore, we switched to another method: The atom has a nucleus that around it circles the electron, so it is sort of clock in itself. Scientists found a specific atom named cesium in which the electrons spin around the nucleus at a stable speed and perfect precision. To measure a second you need to look inside the atom with a beam and count the atomic transitions. The most accurate clocks have their cesium atoms cooled by lasers down to almost absolute zero, minus 273.15 Celsius. Every time the electron in the atom completes 9,192,631,770 revolutions, a second has passed. The accuracy of a cesium clock is 10 to the power of minus 14. An atomic clock is off by one second once in a million years. The atomic clock has been here since 2010 and its working time is between seven to 10 years, and then we will have to replace it.”
Yet even that isn’t accurate enough. Dr. Goldovsky has two clocks, which always average each other out, three antennas on the roof used to synchronize local Israeli clocks with dozens of other clocks across the world (in other government standard labs) and a series of satellites. The laboratory conducts comparisons with 60 countries’ atomic clocks all the time.
Once every few years there is a ‘dramatic’ moment in the time-keeping world. Sometimes it is necessary to change the clocks and add a leap second, explains Goldovsky. Because the earth day is not exactly 24 hours and the rotation speed of the earth changes, it is sometimes necessary to add a second to correct the Coordinated Universal Time to the actual physical time of the rotation of the earth.
Photo by Ronen Marcus.