How do you measure the most accurate time in the world? So accurate it makes GPS and internet synchronization possible? All you need is to use atomic transitions. Sounds easy enough right? Just energy emitted from atoms when they change energy levels.

An ordinary clock uses an oscillating mass and a spring to measure time. Atomic clocks are similar, except that the oscillations are the nucleus of an atom and its electrons. Oscillations occur due to the difference in charge between the positive nucleus and the surrounding electrons. Depending on the temperature of an atom, the electrons oscillate at various frequencies. If given enough energy, the electrons can transition to a different (and measurable) energy level.

For example in a Cesium clock, atoms receive microwave energy at exactly the right frequency to change energy states. A magnetic field in the clock distinguishes atoms that have changed states and a detector provides an output proportional to how many cesium atoms have contacted it. Since Cesium when exposed to an excitation completes 9,192,631,770 oscillations (or Hz, or cycles per second), the peak frequency from the detector is divided by this frequency to provide the ‘ticking of a clock’ at one pulse every second.

So everyone from sailors, truck driver, to pilots rely on atomic clocks because they are accurate and lose less than one second every million years. And every one of the GPS satellite in orbit carries 4 atomic clocks on board, which are used to triangulate time signals to determine position.

And so we get the real point of the article; to introduce the latest development in the line of Seiko Watches, which I recently saw in Pop Sci Mag. The Seiko Astron is a GPS solar watch that recognizes all 39 time zones on Earth by using a network of GPS satellites.

‘Once a day, Seiko Astron receives the time signal automatically and, on demand, connects to four or more of the GPS satellites that orbit the earth, thus pinpointing its position and identifying the time zone and the exact time. The hands adjust automatically to the correct local time with Atomic Clock precision.’ All this technology and innovation is packed into a device the size of an iPod Nano!