A team of physicists at the National Institute of Standards and Technology in Boulder, Colorado, USA have developed an atomic clock that ‘ticks’ about a quadrillion (10 to the 15th) times per second. Eventually it is hoped that this clock will be accurate to 1 second in 30 billion years. This means that the clock would not even lose one second over the entire age of the universe.

The clock works by using the frequency of oscillation of one ion of mercury at optical wavelengths. The atomic clocks first developed in the 1950s used the transitions between energy levels in caesium atoms at microwave frequencies, to monitor time. Because optical wavelengths are so much shorter than microwaves, the potential accuracy of the new clock is unprecedented.Possible applications of the clock include improving satellite navigation and electricity distribution – both of which need precise timing. The clock is due to undergo rigorous testing before being accepted by the international timekeeping community.