It's official: light travels exactly 299,762,458 meters per
second  By , Robert C. Cowen is the Monitor's natural science
editor.  It's official now. The speed of light is exactly
299,762,458 meters per second. There's no ambiguity about it,
none of those ''error bars'' with which scientists indicate the
uncertainties inherent in every measurement. The value of this
fundamental natural constant has been arbitrarily set by
international fiat.  Yet in adopting a fixed value for the speed
of light, the General Conference on Weights and Measures is not
trying to preempt nature. Instead, on Oct. 20, it gave the world
a more accurate standard of length, in which the meter now is
derived from the color of a laser beam with the help of the
agreed-upon light speed.  In doing this, the conference has
taken a giant step toward simplifying our system of weights and
measures so that at least some of the basic units are based
directly on time.  Recommended: Could you pass a US citizenship
test?  The meter now is officially