Tour audio To the nearest femtosecond!

Immerse yourself in a world of extreme accuracy.

The scholarly quest for accuracy has been at the heart of watchmaking innovation since the 17th century. Resonators are a key development in this field: the pendulum, the spring balance and, later, quartz, have all increased timekeeping accuracy. From the Second World War, physicists took over from astronomers and horologists in the pursuit of accurate time measurement. From 1967, the second was no longer defined via astronomical observations such as the passage of the sun across the zenith, but by measuring a microscopic phenomenon: the oscillation of caesium atoms.

A femtosecond, or 0.000000000000001 of a second, corresponds to the imprecision in the ticking of a modern atomic clock. That equates to one second every 3 million years!

This degree of accuracy, which is imperceptible to the ordinary person, is crucial to the organisation of human society: geolocation, navigation, transport and telecommunications systems can only perform so well thanks to the extreme accuracy of the clocks that govern them.