On 2004 Apr 14 , at 8:28 PM, [EMAIL PROTECTED] wrote:
If the meter is 1/10 000 000 the longitudal distance between the north pole and the equator of the planet Earth; and
If the future takes humanity to Mars;
Then would we develop a seperate metric system based on a meter having a length of 1/10 000 000 the longitudal distance between the martian north pole and its equator ... ?
The answer is "NO" there would not be a separate Martian and Earthly metric system.
The main reason is that the derfinition of the metre is NOT "1/10 000 000 the longitudal distance between the north pole and the equator of the planet Earth", and hasn't been since 1889.
Today the metre is defined as the distance that light travels in a specific length of time* (and has been since 1983).
The definition was changed a number of time since it was originally set the one-ten-million the distance from pole to equator on Earth. The main reason was to divorce the definition from artifacts which are not universally available (but also for new definitions that were more precisely measurable). In other words, one of the advantages of abandoning the Earth's size as the basis for the metre was so that visitors to other planets would not be saddled with a definition that would not apply to their planet. The latest definition is the same for all planets (and all those places that are not on planets at all).
By the way, that same advantage applies to making the SI time unit the second NOT defined as a fraction of an Earth day, and NOT making days, hours and minutes part of the SI system or trying to decimalize daily time by changing the size of the second so that it "fits better" into the Earth's day.
Regards, Bill Hooper Fernandina Beach, Florida, USA
PS The specific time in the metre definition is 1/(299 792 458 ) seconds.
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