Les 350 ans de l'Observatoire de Paris

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The metrology laboratory:

One of the specialities of the Paris Observatory is the measurement of time, which is vital today for many activities, in particular for the Global Positioning System (GPS), which could not work without extremely accurate clocks. These clocks are not at all like ordinary timepieces; they are based on the vibrations of atoms under rather exceptional conditions, where they are immobilized and kept under extraordinary stable conditions. Laser beams are part and parcel of these atomic clocks. In 2018, one such clock will be placed in the International Space Station, where it will function in the absence of gravity, which should improve its performance even further.

Droits : Xavier Francolon