On Sun, 18 Jul 1999 14:02:12 -0400 "John Clark" <firstname.lastname@example.org>
>OK, but how long is a second? Is it the time it takes light to travel
>299,792,458 meters? This sort of thing could give circular
>definitions >a bad name.
According to the CRC Handbook of Chemistry and Physics, the second is 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 atom of Cesium 133. That's about 3.75 times the frequency at which a typical microwave oven operates.
. . . . .