These atomic oscillations are so consistent that, in 1967, one second was officially defined in terms of cesium oscillations.

这些原子振荡是如此一致，以至于在 1967 年，一秒被正式定义为铯振荡。

They use ytterbium or strontium – atoms that oscillate at visible light frequencies – and sync up lasers to the atomic oscillations for timekeeping.

他们使用镱或锶——以可见光频率振荡的原子——并将激光与原子振荡同步以进行计时。

A few years ago, NIST built a strontium clock that broke the world record for precision – that’s how accurately a clock tracks atomic oscillations.

几年前，NIST 制造了一个锶时钟， 打破了世界精度记录——这就是时钟跟踪原子振荡的准确程度。