> Of Gene Mechtly > c is now a *defined* constant. >It is no longer a measured quantity. Stability of measurement of c is >no longer an important question.
But if we assume incorrectly that speed is constant, then distance or time (or both) measures will be varied. Distance or time (or both) is used in 4 of the 7 base units and 20 of the 21 derived units. >However, the precision and stability of groups of atomic clocks is an >important question for measuring distances. e.g. for GPS applications. Good example.
