The most accurate clock in the world is redefining the second

By Jen Christensen, CNN

Updated 1731 GMT (0131 HKT) May 25, 2016

Researchers have created this atomic clock using the atoms of the element ytterbium at the National Institute of Standards and Technology in Boulder, Colorado. They say it could be the most precise method of measuring time in the world. Click through to explore other clocks that are important in other ways.
Photos: Keeping time
Researchers have created this atomic clock using the atoms of the element ytterbium at the National Institute of Standards and Technology in Boulder, Colorado. They say it could be the most precise method of measuring time in the world. Click through to explore other clocks that are important in other ways.
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Caral, the oldest ancient city of South America, located in Peru, includes this sundial. The city is thought to be nearly 5,000 years old.
Photos: Keeping time
Caral, the oldest ancient city of South America, located in Peru, includes this sundial. The city is thought to be nearly 5,000 years old.
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The Zytglogge clock tower in Bern, Switzerland, dates to the early 13th century and the clock itself to 1530.
Photos: Keeping time
The Zytglogge clock tower in Bern, Switzerland, dates to the early 13th century and the clock itself to 1530.
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True, the name "Big Ben" refers to the 13-ton bell inside, but honestly, what image says "London" quite like the famous clock and tower?
Photos: Keeping time
True, the name "Big Ben" refers to the 13-ton bell inside, but honestly, what image says "London" quite like the famous clock and tower?
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This antique is the Tiffany clock at Grand Central Terminal in New York. Each day, 700,000 people pass through the terminal, which opened in 1913.<br />
Photos: Keeping time
This antique is the Tiffany clock at Grand Central Terminal in New York. Each day, 700,000 people pass through the terminal, which opened in 1913.
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A million people cheered in Times Square in New York on December 31, 2012, as the clock moved toward midnight and the traditional crystal ball dropped.
Photos: Keeping time
A million people cheered in Times Square in New York on December 31, 2012, as the clock moved toward midnight and the traditional crystal ball dropped.
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Story highlights

  • Current time is measured by atomic clocks
  • Optical clocks measure time better, but the technology has been limited
  • More precise timekeepers could improve GPS, stock trades, the power grid

(CNN)What if everything you knew about time was wrong, and time actually moved at a different rate from what your watch or your phone is telling you right now?

A study released Wednesday in Optica, the Optical Society's research journal, is putting the pieces together about how to get an even better way to keep time.
    Beyond being a great conversation starter in a philosophy class or at the bar, you might want to know about this more precise timekeeper because it could mean better directions, safer travel and even more money in the stock market.
      U.S. gets new, hyper-accurate atomic clock
      U.S. gets new, hyper-accurate atomic clock
      To understand how, you've got to know a little more about how we currently keep time.

      What is time, anyway?

      Read More
      Our understanding of a second is based on a system of technology developed in the 1940s and an agreement among scientists in 1967. Keeping time is a lot more complicated than counting "one Mississippi, two Mississippi."
      A clock counts the intervals of something that happens repeatedly, ideally with as little variation as possible. A second used to be defined as 1/86,400 of the mean solar day, but irregularities in the Earth's rotation make this measurement of time imprecise. To understand how important it is to have a good timekeeper, just ask the captains of ancient ships, whose clocks took them off-course as they neared the equator or the North Pole or moved through humidity.
      Scientists realized they could get a much more exact measure if they could gauge the movement of something more consistent. Enter Nobel Prize winner Isidor Rabi, a physics professor at Columbia University who figured out that a clock could be created from a technique he mastered in the 1930s called atomic beam magnetic resonance.
      Doomsday Clock stays at three minutes to midnight
      Doomsday Clock stays at three minutes to midnight
      Rabi figured out that if you expose subatomic particles to certain frequencies of radiation, the electrons that naturally circle the nucleus of an atom "jump." Measuring this movement as it vibrates between two energy states would be a lot more precise than the swing of the pendulum of your favorite grandfather clock.
      In 1949, the National Bureau of Standards made one atomic clock, and others would soon follow. The technology became so good that in 1967, scientists redefined what a second was.
      The international definition we use now is the time that elapses during 9,192,631,770 (9.192631770 x 10^9) cycles of the radiation produced by the transition between two levels of the cesium 133 atom.
      Get all that? It's tricky. About 400 atomic clocks around the world, interlinked via satellite, help keep global time accurate. The system is considered a million times better as a timekeeper than astronomical-based clocks.

      Why do we need such precision?

      Your spouse probably won't yell at you for being one-trillionth of a second late, but many of our favorite high-tech gadgets depend on this measurement being right.
      Modern telecom equipment requires synchronization to about a millionth of a second per day. Power grids and GPS systems need about a billionth of a second a day. The Internet depends on this accuracy.
      But these atomic clocks are not perfect. They still can accumulate an error of about one nanosecond over a month. In a quest for perfection, scientists want to make this measurement better, and they now think they have a way: optical clocks.

      Building a better time trap

      Optical clocks use atoms or ions that oscillate about 100,000 times higher than microwave frequencies used in atomic clocks. That means they "tick" faster and are more stable over time. Scientists have worked with optical clocks in labs, but they aren't ready for prime time, so to speak.
      "These are fairly complex systems with dozens of lasers that need to be frequency locked at the same time, and they simply break sometimes," said Christian Grebing, author of the new study and a scientist at Physikalisch-Technische Bundesanstalt in Braunschweig, Germany.
      The clock Grebing's team used essentially has a redundant system that can continue to run even when the optical clock breaks down, shrinking the time error to less than .20 nanoseconds over the 25 days it ran.