Jeff Relf wrote in message ...
There's talk of making a Tiny Rubidium clock
to send to the International Space Station in 2008 ,
with a 6.834 billion ticks per second accuracy .

Also , new ( very massive ) optical clocks
count " Laser Oscillations " to record femtoseconds .
That's 10 ^ -15 .

( Each laser oscillation contains Many photons ...
all synchronized , of course . )


From " ABC News. Go. COM " , http://tinyurl.com/hitl ,
July 13 , 2003

The most accurate clocks today
slip by only one second every 30 million years.

For scientists at
the National Institute of Standards and Technology
in Boulder , Colo. ,
that's just not accurate enough .

Instead , they've built a clock designed to only slip by
a second once every 30 billion years .


What good is it?

The various motions of the earth cause clocks to speed up and slow
down all the time anyway! Clocks on Earth and Mars could never agree,
no matter how accurate they were! A clock on the equator will run
faster during the day, when the Earth's rotation subtracts from its
speed of revolving around the sun, and slower at night, when the two
speeds add. And the clock can never stay in sync with clocks at the
poles!


Double-A