Posted on 09/13/2007 1:29:09 PM PDT by presidio9
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.
I thought they only had one guy there who could polish the thing and get the same measured value within 10 micrograms every time. Maybe he’s losing his touch.
Blame GLOBAL WARMING. The shift in the water from ice to liquid is OBVIOUSLY now making our gravity unstable and pretty soon we may all end up floating away...............away.....help!
The article neglects to tell us that the original designer of the cylinder was Jenny Craig.
All kidding aside,it does make one ponder.
Naah. Proton decay. The next bad thing...
Did it lose weight or did it lose mass?...............
Did they ever do a chemical analysis of the alloy? Radioactivity and radioisotopes hadn't been discovered yet in 1889, and traces of radioisotopes within the cylinder may have been present.
So a Kilo will weigh nothing in 2.5 billion years?
What are we going to use to weigh things for the remaining 2.5 billion years before the sun explodes?
But seriously: If the standard kilo suddenly weighs less, doesn’t that mean that everything in the universe suddenly weighs MORE?
But seriously: If the standard kilo suddenly weighs less, doesn’t that mean that everything in the universe suddenly weighs MORE?
Maybe that guy croaked and the new polisher has a fondness for emery cloth.
ping
Apologies to Prof. Irwin Corey. ;o)
That is actually impossible, since The Kilogram always weighs 1 kilogram. Therefore, all other kilogram weights, and possibly all other objects on Earth have increased in weight. Wait...um...no, that’s right.
Did any one else get that Intro to Physics question about how could you tell if the dimension of ever object in the universe was suddenly reduced by 50%?
What is a duck?
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