The new clock is so reliable that it would be off by less than a second if it had started running 100 million years ago, researchers say.

Learn about NIST-F4, the latest cesium fountain clock that now stands as one of the most accurate timekeepers in the entire world.

On July 14, the National Institute of Standards and Technology (NIST) announced their new and improved optical atomic clock is now the most accurate in the world.

The Doomsday Clock has been set to its closest time to midnight in its history, the Bulletin of the Atomic Scientists announced Tuesday.

A new atomic clock is one of the world’s best timekeepers, researchers say — and after years of development, the “fountain”-style clock is now in use helping keep official U.S. time.