The official US timekeepers are upgrading their systems. Since 1999, the National Institute of Standards and Technology has determined the time based on an atomic clock known as NIST-F1. Now there's a new and improved version of the clock—and it's "the most accurate clock of its kind in the world," the institute says. NIST-F2 boasts three times the accuracy of F1. "If you could run either of these clocks for 100 million years, NIST-F1 would lose one second; NIST-F2 would lose 1/3 of a second," says F2's lead designer.
One second is defined worldwide in terms of oscillations of a cesium atom (9,192,631,770 of those oscillations, to be precise). Both clocks determine the time by tossing 10 million such atoms into the air and using lasers to analyze them, the Los Angeles Times explains. What's better about the new clock is that it uses chilled conditions to fight background radiation, thus improving its assessment. Why be so careful? Everything from cell phones to GPS use atomic clock measurements, researchers say, per PC Magazine. "If we've learned anything in the last 60 years of building atomic clocks, we've learned that every time we build a better clock, somebody comes up with a use for it that you couldn't have foreseen," says the designer. (Read more atomic clock stories.)