Two years ago, physicist Jun Ye and his colleagues at the National Institute of Standards and Technology built an atomic clock so precise it doesn't lose or gain a second over the entire age of the universe. Today, they report they've made one ten times as precise using a new technique.
Why it matters: Similar atomic clocks are accurate enough to measure the effects of gravity on time by moving them just a few centimeters up and down. Beyond improving GPS and other time-dependent technologies, atomic clocks could be used to better understand what is below Earth's surface. That could help them model the flow of water, better predict weather or detect magma moving inside a volcano.