The most precise clocks ever built are now testing Einstein, hunting dark matter, and reshaping how we define time itself. In A Nutshell The world’s most precise clocks are changing how we understand ...

Ask someone on Earth for the time and they can give you an exact answer, thanks to our planet's intricate timekeeping system, built with atomic clocks, GPS satellites and high-speed telecommunications ...

Thanks to Einstein’s relativity, time flows differently on Mars than on Earth. NIST scientists have now nailed down the difference, showing that Mars clocks tick slightly faster—and fluctuate over the ...