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The Mouse Ran Up The Clock

By Allan Eastman

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Modern Times

Weltzeituhr (World Time Clock), Alexanderplatz, Berlin

The Weltzeituhr (World Time Clock), found in Berlin, is a modern-day example of time tool development in human history. The clock shows the current time in each time zone.

©iStockphoto.com/TristanH

Increasingly more accurate mechanical clocks remained the main timekeeping Tool until well into the 20th century. But then things began to change rapidly due to the quantum leap in Science and Technology.

The first really major change came with the development of Quartz Clocks by Bell Labs in the USA in the 1920s. They found that if an accurately shaped crystal of Silicon Dioxide could be made to vibrate with AC electricity, it would oscillate at a precisely desired and regular frequency.

From this, it was an easy next step to connect it to a calibrated time display. Initially, this controlled an analog clock face but eventually the timekeeping was designated by an electric pulse and became digital, which meant no more moving parts to wear down.

Already by the 1930s, Quartz clocks were becoming the timekeeping standard. In the post WWII era, they became widely used and the first quartz powered wrist watches made their appearance in the 1960s. The basis for timekeeping Tools became electronic and they provided an accuracy that was much advanced from mechanical devices.

But this process was just beginning. The next major evolution in Time Tools came with the arrival of the Atomic Age. Scientists recognized that the atoms of each element or compound emit electromagnetic radiation at its own characteristic frequency and these resonances are totally stable over Space and Time. They would be the same over millions of years or on the other side of the Universe.

Various elements were tested until Cesium became the main element used in the first really accurate Atomic Clock built in 1955. It quickly became the most used scientific standard of Time measurement and became the official standard in 1967. One “Atomic Second” of Time was defined as “The duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the Cesium-133 atom.”

So, now you know.

The latest versions of Atomic Clocks in the National Institute of Standards and Technology (NIST) in the US are called the Quantum Logic Clocks and are based on the oscillations in Mercury and Aluminum atoms. They are claimed to be accurate to within 1 second in 1 Billion (1, 000,000,000) years.

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The ultimate Tool in bringing this completely accurate Atomic timekeeping to the entire Planet was the establishment of Coordinated Universal Time – UTC – in the 1960s with its full adoption in 1967. At an Institute in Paris, time signals generated by a series of Atomic Clocks in Scientific Institutions from around the World are compared by computer and a weighted average from these signals is generated as the official World Time.

The UTC time signal is sent around the planet electronically. The Network Time Protocol –NTP – was set up in 1985 and remains one of the oldest internet protocols in use. It zips the UTC through the internet accurate to milliseconds. The servers here at timeanddate.com use NTP to provide their service to all of the timepieces on your Personal World Clock. Twenty of them, in my case.

World commerce and technology has become tightly integrated with UTC and NTP for accurate time measurement. Accurate time is crucial to the accurate functioning of the GPS system above us in geosynchronous orbit. Financial transactions, aircraft navigation, the operation of manufacturing robots and most other Time related aspects of modern life have become completely dependent on the integrated GPS, UTC and NTP systems.

One curious sidelight to the development of these most advanced Time Tools is that they have actually become too accurate for the astronomical phenomena they were invented to measure. The official definitions of Time as an expression of the oscillation of cesium atoms does not take into account that the Earth’s rotation is gradually slowing down due to gravitational friction so in effect, our days are becoming longer at a miniscule pace. So corrections to our timekeeping Tools have to be made periodically to keep everything in sync.

This is accomplished by adding a Leap Second from time to time to keep UTC aligned with the rotation of our planet. During 1972, a second was added to UTC on both 30 June and 31 December to catch up.  Since then, another 22 seconds have periodically been added over the last 38 years, at the average rate of 1 second every 1 to 2 years.

So, similar to that incredible transformation from the bone to the satellite in 2001: A Space Odyssey, our Time Tools have evolved from manmade scratches on an antler to an elaborate electronic system based on the vibration of atoms that more or less simultaneously informs the entire Human Race of what Time it really is.

Do we need or will we get even more accurate Time Tools in the future?

Well, Time Will Tell, of course.

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