NASA's Got the Time
If the old cesium
and rubidium clocks were not accurate enough for you, contact NASA's
Jet Propulsion Laboratory. Their newest design is a low-friction model.
It seems previous containers of the ionized atoms used to gauge the
passage of time would rob energy from the atomic system, thereby introducing
errors. The new device uses an ion trapping field, which holds a wad
of ionized mercury atoms in a near frictionless volume for a more perfect
count. You can set your watch by this one; it is accurate to within
one minute every 10 billion years.