The World’s Most Accurate Clocks

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The World's Most Accurate Clocks - Alarm Clock Blog

Of all the world’s inventions, clocks top the list as one of the most enabling technologies of all time. If we didn’t have the precise time, GPS would not function correctly. Not having the correct time would also make it impossible to synchronize networks over long distances. Scientists count on clocks so that they can test the laws of the universe to its depth.

Many of the programs that that assist scientists with the development of standards, improved measurements and the development of technology are funded by the National Institute of Standards and Technology (NIST), which is a federal agency with two main locations in Maryland and Colorado. A physicist named Andrew Ludlow has been working on improving the measurement of time at this agency’s Colorado facilities. His hard work and dedication to an improved clock was recently realized by the unveiling of two of the most accurate clocks ever built. Ludlow presented two of these clocks so that one could check the other’s time. He maintains that the new clocks can measure time with a precision of one part in 10-18.

Andrew Ludlow of NIST

Andrew Ludlow, a true Clock Hero

If you are unsure of how accurate such a clock may be, we will try to put into perspective for you. Ludlow has stated that a measurement of one part in 10-18 is equal to specifying the age of the universe to less than a second. We are quite sure you will agree that this measurement is extremely accurate. Ludlow also compared this new clock’s accuracy to being able to measure Earth’s diameter to less than the width of an atom! You might be wondering what kind of clock pinpoints time so accurately. Good…then read on!

What Type of Clock Keeps Such Accurate Time?

The type of clock that Ludlow unveiled is a chip-scale atomic clock. In principal, this clock is a simple device. The general idea of the clock is that a second is defined by the frequency of light projected by an atom when electrons in a ground state jump to another state. The difficulty of such a clock is measuring this frequency correctly. This is because any small movement of the atom will generate a Doppler effect that will shift its frequency. Stray electric fields can shift these electronic transitions. These stray movements are a phenomenon called Stark shift. Having to overcome these small shifts is the major challenge of building an extremely accurate clock.

Doppler Effect

Doppler Effect

Ludlow and his colleagues have constructed these clocks by using a technology known as an optical lattice clock. Using this approach, they bounced a laser off of a mirror; this created a standing wave of light which formed a lattice to trap atoms. The atoms sit in an egg-like box. They fill this egg box with ytterbium atoms and then zap them with a laser to see the frequency of the electronic transition.

This strange looking egg box is important because it grips the atoms like a vice, and it minimizes Doppler effects. However, electric fields that associate themselves with the light generate the Stark shift that we mentioned earlier. Ludlow and his team get around this by selecting what they call a magic transition in ytterbium where both electronic states make a shift by the same amount. This leaves the transition frequency unchanged. Because the egg box can be filled with a lot of atoms, Ludlow can take measurements by using lots of the atoms to get a clearer signal. The result is a clock that loses only one tick in 10188 tocks. Ludlow measures the accuracy of the first clock to the second to ensure that the measurements are highly accurate. All of this information may sound a little too academic, so we will put it in a simpler way: This clock only loses one second in 50 billion years.

Ludlow has presented what many are calling the next generation atomic clock. The new clocks are making a number of brand new applications. These new clocks are so sensitive that they can measure the gravitational redshift. This is where clocks tick slower in powerful gravitational fields. Essentially, they can see changes in height.

Although the best clocks today are quite sensitive to change, this new clock will be able to measure changes of about 1cm at the Earth’s surface. This will be useful for applications such as geology, hydrology and for measuring the ice pack shifts in climate change studies. The new clock will also allow physicists to test the gravitational redshift and the very fine structure of constant change with position, which is an important fundamental test of physics.

An Optical Lattice Clock

How an Optical Lattice Clock works…

Humanity has always undertaken the ongoing process of improving clocks, which has taken several thousand years. These latest clocks are a culmination of impressive work, but they are bound to be eclipsed in the not too distant future. Ludlow and his team of clock experts are already pointing to improvements that they plan to enact so that their clock can be even more precise. We can’t imagine how accurate they will get in the future, but technology is that way; it just keeps getting better.

How We Use Precise Time Measurement in Our Lives

Accurate time measurements are a part of modern infrastructure; we use it every day. When a telephone call is made, we rely on networks that have to be synchronized to above a millionth of a second per day. Electrical power has to be synchronized to the same standard as the telephone infrastructure. Airline pilots rely on the precise time to better than a billionth second to safely get us to our destinations. Of course, the Internet would be nothing without an accurate measure of time. Most of us wouldn’t want to live in a world without these things. Precise time keeping is what made them possible.

Chip-Based Atomic Clock

How one chip-based Atomic Clock looks…

Earlier, we mentioned that this new clock will be helpful in measuring height. This is important for many reasons. For instance, if there are Earth changes such as a mountain somehow gaining or losing mass, an extremely accurate measurement can be taken to ascertain the changes.

Another area that may be improved with this new technology would be medical imaging. If slight movements can be more accurately measured, the movement of the blood stream, heartbeat and brain activity could make way for new medical imaging. This is always helpful to mankind. Medical imaging can be a warning to take action when a body is not functioning properly. Many times, lives are saved, and health problems are curtailed because of accurate medical imaging.

How This New Clock Helps our Climate

Even with the most sophisticated atomic clocks of our past, elevation changes could only be measured by thousands of feet. However, with Ludlow‘s new invention, elevation changes will be discernible even in slight changes of glacier ice thickness or observable mountain range changes caused by colliding tectonic plates. As you can see, living in a world where time is precise allows us many benefits and lifesaving abilities. The ongoing improvement of time measurement can only mean good things for the future.

The Functionality of a Chip-Based Atomic Clock

Here’s a look at the different parts of one chip-based Atomic Clock

Here at, this new clock invention means that we can be even more accurate than ever. We like that because we don’t want you to miss even a millionth of a second of this great thing called life. After all, we are in the clock business, and anything concerning time helps us to better serve our website’s old and new followers.

We would like to know what you think of Ludlow’s awesome new clock invention. Did you think such accuracy would ever be possible? Feel free to use the comment section of our blog to share your thoughts on this matter of time. salutes Andrew Ludlow for his fantastic clock invention, and we wish him good luck with all of his future endeavors!

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