The first commercial atomic clock

The Atomichron, unveiled on October 3, 1956, was the world’s first commercial atomic clock. At a time when timekeeping is more accurate than ever before, A.S.Ganesh takes a look at atomic clocks and the Atomichron…

In his work of fiction The Time Keeper, American author Mitch Albom has one of his characters say that “man will count all his days, and then smaller segments of the day, and then smaller still – until the counting consumes him, and the wonder of the world he has been given is lost.” While the last part of the statement is rather too deep, and well beyond the scope of this column, there might be some truth with respect to the counting consuming us.

When we started, we looked up at the sun and the moon to get a sense of time. We picked up stones, collected water, and were able to tell time even better. And now, we have come to a stage where the best of our clocks are so precise that it would take around 30 billion years for it to lose even one second.

And yet, at the heart of it, the fundamental process remains the same as we count a periodic phenomenon. In a grandfather clock, the pendulum swings back and forth. In a wristwatch, an electric current ensures that a tuning-fork-shaped piece of quartz oscillates. And when it comes to atomic clocks, we use certain resonance frequencies of atoms and count the periodic swings of electrons as they jump between energy levels.

The best of our clocks, by the way, are atomic clocks. As we learned more of the atom’s secrets, we were able to build practical applications, including these clocks.

We now know that an atom is made up of a nucleus – consisting of protons and neutrons – that is surrounded by electrons. While the number of electrons in an element can vary, they occupy discrete energy levels, or orbits.

Electrons can jump to higher orbits around the nucleus on receiving a jolt of energy. As an individual element responds only to a very specific frequency to make this jump, this frequency can be measured by scientists to measure time very accurately.

By the mid 1950s, atomic clocks with caesium atoms that were accurate enough to be used as time standards had been built. The Massachusetts Institute of Technology Research Laboratory of Electronics developed the first commercial atomic clocks around the same time, and these were manufactured by the National Company, Inc. (NATCO) of Malden, Massachusetts.