Johnathan McClure wrote: >Why is it that the meter has been tied to the speed of >light (in a vacuum) when we are finding out how variable >that "constant" can be? What was so wrong with >Krypton Lasers?
If I understand it correctly, the ambition of those who define standards is to make them as universal as possible. The original definitions were according to physical items held in places such as Paris and London. This meant that people needed to take their copies back to Paris or London to get them recalibrated. If you have a definition that is based on something that can be measured anywhere on the planet that is better. Better still would be to have something that can be measured anywhere in the Universe. That is why it is good to have things based on the speed of light which is the most constant thing in the universe.
