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.
My science teacher in Junior High in the late 60’s always corrected us saying,”A pound is weight! A gram is mass!”...........
Didn't Steven Wright once say that somebody stole all of his furniture ... and replaced it with exact duplicates?
Yes, a man who used to weigh 100 kg would now weigh, say, 102. So he goes to the doctor and doctor warns him to watch what he eats—he’s just put on two kilos.
Maybe the gravitational field strength changed.
Rust never sleeps.
The speed of light was defined in 1983 as exactly 299 792 458 meter/s. A meter is how far light travels in 1/299 792 458th of a second.
The platinum-iridium cylinder has been the standard for over 100 years, I believe. The mass of water at 4 C is too hard to do reliably.
A second is is the time it takes for 9 192 631 770 oscilations of a specific wavelength of light emitted by the cesium-133 atom.
Proposals have been made to change it to something more concrete (I remember my chem teacher describing a kilo as a mole worth of an element) but the actual decision to do so hasn’t happened yet and is currently scheduled for a time 3-4 years from now.
How about minute shifts in gravity?
[grin]
Impermanence
change in gravity...
The damn French have lost control of the kilo. Better let Poland or the Czech Republic have it for a while, so they can fatten ‘er up.
Dumplings, you know....
Some pretty colors and large letters, looks like a periodic chart, but to say what it actually is I cannot ‘cause the darn print is so small on my screen. Meany!
It’s the Atkins Diet! Feed that thing some carbs, man!
Atlantic Monthly’s Periodic Table of Rejected Elements from August 1999. :’)
FWIW:
Maranhao State University, Physics Department, S.Luis/MA, Brazil.
Copyright Ó 2006 by Fran De Aquino
All Rights Reserved
It was observed that samples hung above a thermoionic current exhibit a weight decrease
directly proportional to the intensity of the current. The observed phenomenon appears to be
absolutely new and unprecedented in the literature and can not be understood in the
framework of the general relativity. It is pointed out the possibility that this unexpected effect
is connected with a possible correlation between gravity and electromagnetism.
http://lanl.arxiv.org/ftp/physics/papers/0610/0610075.pdf
Gravity is not behaving as theory suggests it should behave:
http://www.thunderbolts.info/tpod/2007/arch07/070912pioneeranomaly.htm
According to our current ‘understanding’ of gravity, over the last 34 years both Pioneer 10 and 11 should have traveled more that 400,000 kilometers further than they have actually flown.
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