Scientists developed a highly accurate optical ion clock, improving time measurement precision by 1,000 times.

Not that the present situation and the abundance of free time that many are experiencing has anything to do with [Leo Fernekes] all-transistor digital clock build, which he started a year ago ...

This kind of clock has been around for many years and in many ancient cultures. China may have had them as early as 4,000 BC and India possibly around 2,500 BC. Egypt developed them somewhere ...