Posted on 09/12/2007 2:47:48 PM PDT by decimon
By JAMEY KEATEN, Associated Press Writer 6 minutes ago
PARIS - A kilogram just isn't what it used to be. The 118-year-old cylinder that is the international prototype for the metric mass, kept tightly under lock and key outside Paris, is mysteriously losing weight — if ever so slightly.
Physicist Richard Davis of the International Bureau of Weights and Measures in Sevres, southwest of Paris, says the reference kilo appears to have lost 50 micrograms compared with the average of dozens of copies.
"The mystery is that they were all made of the same material, and many were made at the same time and kept under the same conditions, and yet the masses among them are slowly drifting apart," he said. "We don't really have a good hypothesis for it."
The kilogram's uncertainty could affect even countries that don't use the metric system — it is the ultimate weight standard for the U.S. customary system, where it equals 2.2 pounds. For scientists, the inconstant metric constant is a nuisance, threatening calculation of things like electricity generation.
"They depend on a mass measurement and it's inconvenient for them to have a definition of the kilogram which is based on some artifact," said Davis, who is American.
But don't expect the slimmed-down kilo to have any effect, other than possibly envy, on wary waistline-watchers: 50 micrograms is roughly equivalent to the weight of a fingerprint.
"For the lay person, it won't mean anything," said Davis. "The kilogram will stay the kilogram, and the weights you have in a weight set will all still be correct."
Of all the world's kilograms, only the one in Sevres really counts. It is kept in a triple-locked safe at a chateau and rarely sees the light of day — mostly for comparison with other cylinders shipped in periodically from around the world.
"It's not clear whether the original has become lighter, or the national prototypes have become heavier," said Michael Borys, a senior researcher with Germany's national measures institute in Braunschweig. "But by definition, only the original represents exactly a kilogram."
The kilogram's fluctuation shows how technological progress is leaving science's most basic measurements in its dust. The cylinder was high-tech for its day in 1889 when cast from a platinum and iridium alloy, measuring 1.54 inches in diameter and height.
At a November meeting of scientists in Paris, an advisory panel on measurements will present possible steps toward basing the kilogram and other measures — like Kelvin for temperature, and the mole for amount — on more precise calculations. Ultimately, policy makers from around the world would have to agree to any change.
Many measurements have undergone makeovers over the years. The meter was once defined as roughly the distance between scratches on a bar, a far cry from today's high-tech standard involving the distance that light travels in a vacuum.
One of the leading alternatives for a 21st-century kilogram is a sphere made out of a Silicon-28 isotope crystal, which would involve a single type of atom and have a fixed mass.
"We could obviously use a better definition," Davis said.
Selective Entropy.
No.
Global warming? Bush’s fault? It’s getting older and shrinking?
Take your pick.
On second thought, that would be about 8 billion per second - stand back!
Have Gun, Will Travel
Wire Palladium, San Francisco
As in, “Why are women such poor judges of distance?” “Because they are constantly being told that this < holding hands 6” apart > is eight inches.”
What happens if you join a new squadron where someone already has your call sign?
Incidentally, my Dad's was "Pretty Lights", earned on a P-51 sortie over Norway in 1944. He noticed some twinkling lights at the rim of the fjord they were flying up, and blurted out "What are those pretty lights up there?" over the radio. The squadron leader immediately veered into a turn, knowing it was flak aimed straight at them. I don't know if his sharp eyes made up for breaking radio silence, but that became his name in the squadron (No. 19, RAF).
-ccm
I believe that they are comparing it to other secondary standards, on both sides of the same precision balance beam. The relative weights have changed, and apparently the “primary” standard has drifted away from all the copies, which makes absolutely no sense. Entropy has absolutely nothing to do with it, there isn’t that much entropy in the universe. (At least in the sense of uncontrollable random variations. Procedural errors cannot be rules out.)
See post 70 first.
When they stopped pulling it out all the time, or standardized handling procedure, I have no idea.
If they had done the right thing and stayed with pounds and ounces, they would not be having this problem now.
Great point, oh Great One! The primary problem with the metric system (aside from its French origins) is that it has no purely human referent. A foot...well, MY foot, for example, is exactly one foot long. An inch is the width of a thumb...and MY thumb is exactly one inch across. Horses are measured in “hands” of four inches - and mirabile dictu, MY hand is four inches! When it comes to measurements I guess I’m just lucky! :-) Now, the human variation in appendages would not make any individual the benchmark for science...but if I want to move something an inch, a foot, a yard, I can get there with a quick approximation using my body as a tool. Using the metric system, there is NO human relationship to ANY unit of measure; it is UNnatural, inhuman, arbitrary, and unrelated to our everyday knowledge and experience. So just chalk metrics up to the insanity of our Froggish brethren (and cistren) - I’ll keep my old-fashioned and ever-handy inches, thankyewveddymuch! :-)
Next to Bush’s Weather Machine, he has a Mess-With-The-French Machine.
I like that machine the best.
Gadzooks, nice to know my devout followers... 
know the proper form of address!
Now, as to your luckiness, True... 
I, on the other hand, have the perfect measurement for 8 inches.
Oh... 
My... God!
What! What? Ya'll... 
never heard of a socket wrench?
Ah, I think I see...too much energy required to diffuse that amount of weight from this non-organic structure? Is that approaching the ballpark?
New Disney film coming out: “Honey, I shrunk the kilogram!”
Looking for a socket wench? :-)
I do appreciate it, thanks.
So use the weight that was originally recorded 118 years ago and be done with it. Any minute change now doesn’t matter now unless you’re a lunatic. Jeez, worse than the stock market guys!
It also might be related to the moving of the magnetic north. If the poles are moving so is the earth’s liquid core, and local gravity has also changed.
It could also be dissolved gases in the metal.
Too many things could cause it. It will take a bunch of researchers several years to determine the cause.
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