Note: this topic is from 9/12/2007. Thanks decimon.
· String Theory Ping List ·
· Join · Bookmark · Topics · Google ·
· View or Post in 'blog · post a topic · subscribe ·
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.
That is only approximately true. To eight significant figures, a kilogram equals 2.2046226 pounds.
Of course, that would be 2.6792289 troy pounds.
I think the problem with the cylinder in Paris is that it has different and changing magnetic properties for some reason. Since a mass, or energy loss is out, the only force left is the magnetic force, in the Earth's field and that of the surrounding balance. They account for that, but they'll have to look closer. The link is technical, but shows how they attempt to weigh them in different orientations. They may have assumed that the magnetic properties are the same, but they're not.
Hmmm... Magnetic forces. Interesting idea.
As I’m sure you know, squadrons also have aircraft call signs (usually made up of the squadron identification letters and the last digit or two of the aircraft tail number). These, of course, remain with the squadron and the aircraft.
My father served in England as a B-24 bomber crewman with the U.S. 8th Air Force. Flew 120+ missions (no 25 mission limit for pre-war regular Army soldiers) ranging all over western and northern Europe (including some up to Norway). However, lately I’ve begun to suspect he might also have been in one of the B-24 squadrons “loaned” to 15th Air Force to help carry out the mass raids on the Polesti refineries in Romania.
Unfortunately, it is impossible to check. He passed away in 1975 at the age of 56 and the St. Louis archives fire of the 1950's destroyed a great number of the stored service records of 8th Air Force personnel, including my father's.
Yep.
All of the others are heavier by a fingerprint...
Hmmm.
Apropos of nothing, I believe the United States Constitution is inspired (almost to the point of plagiarism) from the writings of one Charles de Secondat, baron de Montesquieu.
I have got to get on this weight loss program. I could lose 20 pounds in ... only about 23 billion years!
Note: this topic is from 9/12/2007. Thanks decimon.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.