ROYAL GREENWICH OBSERVATORY / SCIENCE PHOTO LIBRARY. ROYAL GREENWICH OBSERVATORY / SCIENCE PHOTO LIBRARY.
Repairs completed to the atomic clock, the most accurate type of clock known to date. The periodic process used as the timing mechanism is an atomic or molecular event which is associated with a constant & accurately known frequency. In other words the time scale is derived from the vibrations of atoms or molecules. Various atoms (caesium, as in this example) & molecules (ammonia) have been used in the clock.
Model release not available. Property release not required.