real time

Atomic clocks: tick tock, they don’t stop

Let’s take a second to reflect on the second. What is it, exactly? How do we measure it? Look no further than atomic clocks and their ever-improving accuracy and reliability. What is at stake? Anything from major technological progress to day-to-day applications.

Measuring the second: a race against time
For the longest time, measuring time itself was an “astronomical” issue involving calculations based on the Earth’s rotation and its revolution around the sun. Then, in 1956, everything changed. Time became atomic. Even today, the second is measured based on the frequency of radiation cycles of a caesium-133 atom. Because this frequency is extremely fast and reliable, it provides an accurate measurement. Caesium-133 is, in one sense, a perfect and unwavering metronome.

The increased accuracy gained from this new reference point enabled us to build surprisingly stable atomic clocks. There are 350 in the world—plus those loaded onto satellites—and they are only getting more precise with time. Scientists are in a constant race to greater and greater accuracy, with new records being set on a regular basis. In April 2015, an American team designed a clock guaranteed to be stable “for 15 billion years”, i.e. longer than the Earth’s life expectancy.

But why spend all this energy conquering measured time?

Because many technologies we use daily require extraordinarily precise timekeeping.

After one nanosecond, turn left…
For example: you are driving and your GPS gets your exact position wrong, insisting you make several detours to reach the very highway on which you are already cruising at high speed. How annoying! The issue is that your GPS operates by timing the signal that connects your car to several satellites. A one-millionth of a second deviation in data transmission, and your position can be off by up to a 1,000 feet! To reach this kind of accuracy, the world’s finest wristwatch is about as useful as the old carriage clock in your living room.

In the realm of GPS technology alone, improving atomic clocks is expected to bring many valuable developments: more reliable autopilot systems, automated drone deliveries, improved emergency beacons—say, to locate avalanche victims—and many more applications.

Lighting up data traffic lights
And what about traffic on the information superhighway? The digitization of all that we do has resulted in explosive amounts of data transfers. Data traffic around the world continues to balloon, growing by 63% between 2015 and 2016 to reach 88.7  billion gigabytes per month. This increase should accelerate even further as more individual uses and connected devices become widespread.

Timekeeping enters the picture through the monitoring systems that prevent horrendous traffic jams inside data centers by ensuring compliance with data delivery times, down to the nanosecond. This requires infallible atomic clocks. Therefore, if you intend to stream a movie in virtual reality while chatting with other viewers in the next few years, scientists will have to continue perfecting atomic clocks.

88.7 billion
Data traffic in gigabytes around the world by month

“This is your atomic clock speaking. At the next beep, you will be on planet Mars.”
Lastly, there can be no conquest of space without mastery of time. Whether we wish to correct the course of machines millions of miles away, order a space probe to take samples from the surface of Neptune or transmit precise information to astronaut pioneers on Mars, we will rely on increasingly accurate time measurements.

What, in the end, does our ability to measure time depend on? Finding the fastest and most reliable metronome in the entire universe. The atomic clock is the finest drum kit in the great jazz orchestra of the cosmos, keeping perfect rhythm and never missing a beat. It provides the fundamental groove for humanity’s most ambitious improvisations into time and space. And if, tomorrow, we seek a universal language to communicate with all species—terrestrial or extra-terrestrial, living or inert—the atomic clock will give us the primordial pace for truly universal speech.

The time that passed between the very first pendulum to the most recent atomic clocks may have felt very long. But really, it has only gotten more precise—and we are just getting started.

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