ABSTRACT
What is the use of accurate time? Why should anyone need to know the time to millionths or even billionths of a second? On the face of it, this degree of accuracy seems extravagant and quite irrelevant to everyday life. Surely only a few experimental scientists need to measure time to such precision? Yet, as we shall see in this chapter, the economy of the developed world is coming to rely ever more heavily on accurate time generated by atomic clocks. Without those clocks, much of modern life would simply not be possible.
