The length of a second could be about to change

For nearly 50 years, the length of a second has been defined in the same way. But researchers in Germany now believe they have found how to make the most accurate clock ever created, which keeps time so well that if it had started 14 billion years ago at the Big Bang it would have lost just 100 seconds. While the change in accuracy would hardly be noticed by humans, it could actually be significant for GPS navigation – increasing the accuracy on the ground from a few metres to a few centimetres – as well as electrical power grids and computerised financial networks.

http://www.independent.co.uk