Doesn't it depend upon gravity (aka sea level)? Is that standardized?
Hal, Yes and no. The SI second is defined in the local reference frame. So your cesium clock at sea level ticks SI seconds for you there. Your cesium clock on a mountain ticks SI seconds for you there. The fact that the two clocks will disagree when compared with each other is true; but both clocks are still ticking SI seconds in their own frames. Now to make a time-scale out of these identical but differing SI seconds does require some statement of common elevation. So this is why reported clock data is all adjusted to sea level in the computation of TAI (and hence UTC). /tvb _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs