Super clocks: More accurate than time itself

The atom clocks that supply the heartbeat of modern life have become so accurate that they are exposing the elusive nature of time itself.

A new generation of atomic tickers, known as optical clocks, have just wrested the record for accuracy from the ensembles of oscillating caesium atoms that held it for half a century. Soon, the new technology will be so refined that if such a clock had ticked away every second since the big bang 13.7 billion years ago, it would not yet have missed a beat. That is an awesome accomplishment - but it's also a problem. At this astonishing precision, we might have to rethink not only how we measure time, but also our concept of time.

A brief history of timekeeping on NewScientist