Monthly Archive for September, 2010

Another quite fascinating piece by Babbage on Time as a concept. It explains the famous story of the pendulum that went up in the air and came back down—younger.

Obviously not even the finest Swiss timepiece can boast the accuracy required to detect such minute shifts. So physicists have come up with “atomic” clocks that rely on some fundamental physical properties of electrons in an atom. Normally, these reside on specific energy levels but when electromagnetic waves of a particular frequency are shone on them, they absorb energy and jump to a higher level. As they re-emit the energy, they drop back down. By creating a feedback loop which has electrons continuously hopping between two levels, physicists are able to construct an ultrafast and extremely consistent subatomic pendulum. The clocks currently used to set the international time standard rely on microwaves with a frequency of 9.2 billion cycles per second being shone on cesium atoms.