New superclock redefines the length of a second

Scientists have developed a new timekeeping device which loses only one second each 300 million years. It is unlikely to make anybody more punctual – so why are scientists excited?

For just £10 it is possible to buy a digital watch which loses roughly one second every 30 years. With a timepiece like that you could live a long life without ever being more than three seconds late. For most people, that is easily accurate enough.

But however small this inaccuracy seems for the purposes of everyday life, it is still a significant error. Many academics devote entire careers to the quest for a perfect clock. And now these researchers are celebrating a major breakthrough: a new device, known as an optical lattice clock, which loses just one second every 300 million years – three times more precise than the most accurate atomic clock to date.

The optical lattice clock is an extremely intricate machine. A group of freezing atoms are targeted with a laser beam and forced to spin at a rate of tens of billions of oscillations per second. By recording these minuscule movements, which are extremely regular, scientists can calculate almost exactly how much time has passed.

This is not simply an exercise in extreme pedantry. Although such levels of accuracy are totally unnecessary in everyday life, there are areas in which they make a genuine difference. Particle physics, satellite navigation, financial markets and telecommunications are all affected by even the tiniest discrepancies in timekeeping.

For most of history, the spinning of the Earth has been our ultimate means of measuring time, as observed in the movement of cosmic bodies like the sun.

But astronomers now know that our planet actually wobbles on its axis, meaning that each rotation takes a marginally different length of time. What is more, these rotations are getting very slightly slower each year.

Ancient civilisations had other ingenious methods of keeping time, too. In the Middle East, water clocks marked the passing of the hours by counting gradual drips. In China, monks burned incense which changed its smell at regular intervals.

But the heavens have always been our gold standard – until the invention of the atomic clock.

The end of time

For the scientists who strive to perfect the atomic clock, this is a story of tremendous progress. A thousand years ago, sundials were the best clocks we had, and minute and second hands were only introduced after the invention of pendulum clocks in the 17th Century. Now we can be accurate to within the tens of billionths of a second.

But Kristen Lippincott of London’s National Maritime Museum is one of several experts who lament the passing of astrological time. ‘The sun, moon and stars are important to our lives,’ she says: ever since the birth of science, skygazing has given us a sense of time and place. We lose something by replacing the heavens as our guide with a rigid atomic tick.

You Decide

  1. Do you think science will ever tell us how long a second is with 100% accuracy?
  2. Should time be measured by counting regular intervals or looking at the sun, moon and stars?

Activities

  1. Imagine all the clocks in the world suddenly stopped working. As a class, try to imagine what the consequences would be.
  2. Do some research into an early clock and write a brief explanation of how it worked (with diagrams, if you wish).

Some People Say...

“Alarm clocks are the worst invention in human history.”

What do you think?

Q & A

Laser firing clocks sound pretty impressive, but I think I’ll stick with my Casio.
That’s probably for the best. Even the inventors of the new atomic clock admit that it will ‘never be used in homes’. But even if you never see a device like this, there are ways in which it could indirectly influence your life.
Like what?
Well for one thing it could eventually improve the speed of your internet connection. And it could also make sophisticated financial transactions called high frequency trading more efficient, with possible benefits to the global economy. But it’s also fascinating for a theoretical reason: scientists still struggle to find any object or process in nature which is totally predictable and fixed.

Word Watch

Atomic clock
A clock which uses the movement of atoms to measure time. The first model was completed in 1949.
Oscillations
The current definition of a second is based on a previous method by which atoms are bombarded with microwaves. This process produces 9,192,631,770 circuits every second. But the discovery of the optical lattice clock is expected to result in a change to this definition.
Pedantry
An obsession with accuracy and detail. The word comes from an old French name for a teacher.
Astronomers
Scientists who study space. Not to be confused with astrologers, who study the very unscientific discipline of horoscopes!
Slightly slower
This is due to the gravitational pull of the moon. If you could go back to the time of the dinosaurs, you would find that an average day lasted only 23 hours rather than 24!

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