Atomic clock. The Atomic Clock To define the time as accurately as possible, the Cesium atoms are measured in different energetic conditions: The Cs-atoms evaporate in an oven and get magnetically sorted, whereby only atoms of a low energetic condition get into the cavity.
There, the atoms are animated to change their condition through radiotherapy with a microwave field. The atoms that changed their condition are collected in a special chamber. At a certain frequency, the amount of collected atoms is on its climax. Local time Belgium - Brussels. The official U.S. time. Timeanddate.com.