John Smith I wrote:
wrote:

...
"Under the International System of Units, the second is currently defined
as the duration of 9,192,631,770 periods of the radiation corresponding
to the transition between the two hyperfine levels of the ground state
of the caesium-133 atom. This definition refers to a cesium atom at rest
at a temperature of 0 K (absolute zero)."


Now, I do constantly worry about my understanding of such things; and,
if they are in error will seek to "update" them. But, the example you
just gave me is about the weakest and most worrisome I have seen ...

What example?

Are you saying you don't believe that is the definition of the second
since 1967 or that you don't understand the definition?

Start with:

http://physics.nist.gov/cuu/Units/second.html

http://tycho.usno.navy.mil/cesium.html

--
Jim Pennino

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