A new atomic clock is keeping the US on time: As the Washington Post reports, if the extremely accurate clock ran for 100 million years, it would only be off by less than a second. What makes the National Institute of Standards and Technology's NIST-F4 so accurate is its "fountain" design, representing "the gold standard of accuracy in timekeeping," per a release. It uses lasers to cool thousands of cesium atoms to near absolute zero, then measures the frequency of the atoms as they pass through microwave radiation, burbling up and down like water in a fountain as they oscillate between quantum states at a frequency of over 9 billion times per second, per the Post. The exact count defines the official international second.
There are fewer than 20 such clocks operating around the world. "Painstakingly assembled and tested over the last few years," NIST-F4 is kept at NIST's campus in Boulder, Colorado. Pending approval before it can join the other 450 clocks defining Coordinated Universal Time, per Live Science, it has already improved time signals that are "used literally billions of times each day for everything from setting clocks and watches to ensuring the accurate time stamping of hundreds of billions of dollars of electronic financial transactions," says Liz Donley, chief of NIST's Time and Frequency Division.
However, countries are considering redefining the second "in terms of one or more different atomic elements used in so-called optical clocks that can measure time even more precisely" as early as 2030, per the release. At that point, cesium fountain clocks will take on a "diminished" role in timekeeping. (More atomic clock stories.)
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