An atomic wristwatch? Er, not right now thanks!

‘Scientists at the National Institute for Standards and Technology in Boulder, Colorado, have taken portable time keeping to new levels of accuracy with the creation of the device, which is driven by inner workings barely bigger than a grain of rice…By contrast, the atomic clock would be accurate to within a second every 300 years, making it more than 1,000 times more reliable than a very good wristwatch.’