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Shrinking kilogram bewilders physicists
Associated Press | Sep. 12, 2007 | JAMEY KEATEN

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.


TOPICS: Miscellaneous; News/Current Events; Technical
KEYWORDS: kilogram; stringtheory
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I was going to go for iridium siding but now I don't know.
1 posted on 09/12/2007 2:47:50 PM PDT by decimon
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To: decimon

It’s evolving.


2 posted on 09/12/2007 2:49:02 PM PDT by RightWhale (Stop Change while it is perfect.)
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To: decimon

Would it be too far fetched to say this demonstrates entropy?


3 posted on 09/12/2007 2:49:40 PM PDT by Recovering_Democrat ((I am SO glad to no longer be associated with the party of Dependence on Government!))
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To: decimon

The Guiness diet?


4 posted on 09/12/2007 2:49:50 PM PDT by mnehring (What does the Ron Paul Rorschach test say about you?)
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To: decimon

mice


5 posted on 09/12/2007 2:49:51 PM PDT by nuconvert ("Terrorism is not the enemy. It is a means to the ends of militant Islamism." MZJ)
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To: dighton; martin_fierro; jdm; cyborg; Tijeras_Slim

Doesn’t everybody’s Gram get smaller as she ages? It’s usually osteoporosis.


6 posted on 09/12/2007 2:50:16 PM PDT by Petronski (Cleveland Indians: Pennant -11)
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To: decimon
50 micrograms is roughly equivalent to the weight of a fingerprint.

You don't suppose that's the answer right there, do you?

7 posted on 09/12/2007 2:50:57 PM PDT by Oberon (What does it take to make government shrink?)
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To: decimon

Next time don’t allow trace amounts of tofu in your metal castings!


8 posted on 09/12/2007 2:51:09 PM PDT by ikka
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To: Recovering_Democrat
Would it be too far fetched to say this demonstrates entropy?

That was my first thought.
9 posted on 09/12/2007 2:51:26 PM PDT by JamesP81
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To: decimon

That’s 0.005%. Give me a break. Pierre miscalibrated the scale when he was measuring it.


10 posted on 09/12/2007 2:51:57 PM PDT by stm (Fred Thompson in 08!)
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To: decimon
Since global warming is doing a "Titanic", this would give the libs a whole new scare:

Global Shrinking.

Are you sure you're not getting small?


11 posted on 09/12/2007 2:53:23 PM PDT by capt. norm (Be thankful we're not getting all the government we're paying for.)
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To: decimon

I thought my last bottle for french wine looked a little short. This explains it.


12 posted on 09/12/2007 2:53:44 PM PDT by UglyinLA
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To: decimon

The last guy who used it dropped it and nicked off a corner?


13 posted on 09/12/2007 2:54:00 PM PDT by FatherofFive (Choose life!)
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To: decimon

The copies have probably oxidized a bit and gained weight—sort of like I have.


14 posted on 09/12/2007 2:54:06 PM PDT by Cruising Speed
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To: RightWhale

Like the definition of 6 inches?


15 posted on 09/12/2007 2:55:15 PM PDT by SmithL (I don't do Barf Alerts, you're old enough to read and decide for yourself)
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To: decimon

The NIST was working on a replacement for the Kilo-gram a few years back involving magnetic energy force. I guess they’re still working on it..........


16 posted on 09/12/2007 2:56:01 PM PDT by Red Badger (ALL that CARBON in ALL that oil & coal was once in the atmospere. We're just putting it back!)
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To: Logophile

“We could obviously use a better definition,” Davis said.

I thought you might appreciate this thread : )


17 posted on 09/12/2007 2:56:34 PM PDT by LeGrande (Muslims, Jews and Christians all believe in the same God of Abraham.)
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To: decimon

Sometimes there’s a silver lining to the cloud. A similar weight discrepancy led a researcher to hypothesize that carbon might have a different configuration in nature than Diamonds, C-6, C14, and others, so he generated C-60 and C-72 to account for the weight discrepancy and we now have buckyballs. There could be something here worth researching.


18 posted on 09/12/2007 2:56:39 PM PDT by Kevmo (We should withdraw from Iraq via Tehran. And Duncan Hunter is just the man to get that job done.)
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To: Recovering_Democrat

Local gravity may have changed slightly..............


19 posted on 09/12/2007 2:57:19 PM PDT by Red Badger (ALL that CARBON in ALL that oil & coal was once in the atmospere. We're just putting it back!)
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To: decimon

Global Shrinking! Bush’s fault!


20 posted on 09/12/2007 2:57:45 PM PDT by PhatHead
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To: Recovering_Democrat
Would it be too far fetched to say this demonstrates entropy?

Must we always talk politics? :-)

21 posted on 09/12/2007 2:57:57 PM PDT by decimon
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To: Oberon

someone cleaned it and didn’t tell anybody?..........


22 posted on 09/12/2007 2:57:57 PM PDT by Red Badger (ALL that CARBON in ALL that oil & coal was once in the atmospere. We're just putting it back!)
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To: Cruising Speed

Rusty? Izat you?


23 posted on 09/12/2007 2:58:00 PM PDT by null and void (<---- Awake and filled with a terrible resolve...)
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To: Recovering_Democrat
"Would it be too far fetched to say this demonstrates entropy? "

Yes.

24 posted on 09/12/2007 2:58:34 PM PDT by spunkets ("Freedom is about authority", Rudy Giuliani, gun grabber)
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To: decimon

Proton decay. Of course that’s A LOT of protons.


25 posted on 09/12/2007 2:58:44 PM PDT by zencat (The universe is not what it appears, nor is it something else.)
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To: decimon
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

Probably from Hillary sneaking in there every night and 'polishing' it.
26 posted on 09/12/2007 2:59:18 PM PDT by reagan_fanatic (Ron Paul put the cuckoo in my Cocoa Puffs)
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To: Cruising Speed
The copies have probably oxidized a bit and gained weight—sort of like I have.

Rusty? Is that you?

27 posted on 09/12/2007 2:59:31 PM PDT by TC Rider (The United States Constitution ? 1791. All Rights Reserved.)
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To: Red Badger
Local gravity may have changed slightly..............

Good thought, but the copies are being weighed in the small local gravity field as the original.

28 posted on 09/12/2007 3:00:07 PM PDT by Cruising Speed
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To: Red Badger
Local gravity may have changed slightly.........

That's it. Sarkozy brought gravitas.

29 posted on 09/12/2007 3:00:32 PM PDT by decimon
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To: decimon

I thought the gram (a thousand of which make up a kilogram) is just the weight of a cubic centimeter of pure water.

The centimeter in turn was taken from a measure of the earth’s arc and then brought down to a usable dimension. This was done, I believe, at the behest of the French Revolution’s drive for objective standards.

Heck, that is what I learned in physics.


30 posted on 09/12/2007 3:00:49 PM PDT by bajabaja
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To: Recovering_Democrat

Slow release of gases entrained during the original casting process?


31 posted on 09/12/2007 3:01:05 PM PDT by Captain Rhino ( Peace based on respected strength is truly peace; peace based on weakness is ignoble slavery)
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To: Cruising Speed

While the Metrologists were out to lunch, the cleaning lady, from Chad, came in and saw it was kinda dull, so she polished it for them............


32 posted on 09/12/2007 3:01:05 PM PDT by Red Badger (ALL that CARBON in ALL that oil & coal was once in the atmospere. We're just putting it back!)
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To: reagan_fanatic

I bet she ain’t never polished a shiny knob in her life!................


33 posted on 09/12/2007 3:02:47 PM PDT by Red Badger (ALL that CARBON in ALL that oil & coal was once in the atmospere. We're just putting it back!)
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To: decimon

Everything looses weight over time (except my wife). My one pound of coffee (16 oz) is now 11.5 oz.


34 posted on 09/12/2007 3:03:14 PM PDT by Ruy Dias de Bivar (Ever see WILLIS SHAW backwards in your rear view mirror? I have!)
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To: TC Rider
Rusty?

Yep, rust in my joints and some spare mass around the middle, too.

35 posted on 09/12/2007 3:03:55 PM PDT by Cruising Speed
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To: decimon
So much for uniformity.

ML/NJ

36 posted on 09/12/2007 3:04:19 PM PDT by ml/nj
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To: decimon

Don’t be crazy, go with the Hardy Planck
you’ll be glad you did.


37 posted on 09/12/2007 3:05:04 PM PDT by tet68 ( " We would not die in that man's company, that fears his fellowship to die with us...." Henry V.)
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To: Cruising Speed
They can use mine: \
38 posted on 09/12/2007 3:05:30 PM PDT by Red Badger (ALL that CARBON in ALL that oil & coal was once in the atmospere. We're just putting it back!)
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To: decimon

39 posted on 09/12/2007 3:05:54 PM PDT by StevieJ
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To: Cruising Speed; TC Rider

*ahem* So what am I? Chopped liver???

See post #23...


40 posted on 09/12/2007 3:06:10 PM PDT by null and void (<---- Awake and filled with a terrible resolve...)
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To: spunkets

Why?


41 posted on 09/12/2007 3:06:42 PM PDT by Recovering_Democrat ((I am SO glad to no longer be associated with the party of Dependence on Government!))
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To: decimon

Global warming causing it to expand and become lighter.

Just a guess ;)


42 posted on 09/12/2007 3:07:08 PM PDT by grjr21
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To: bajabaja

Yes, but water (with its various isotopes of hydrogen and oxygen) varies slightly in weight from sample to sample (as well as with temperature) and thus they wanted something more stable. Thus, the cylinder reference.

They could define it using the cubic decimeter of water again, using and H-1 as the references, 101325 Pa pressure (assuming said atmosphere is saturated with water) and 277.14 K (the point at which water is most dense) and I think you’d probably be able to get a stable enough standard for it. Of course, that’s just my speculation.


43 posted on 09/12/2007 3:07:08 PM PDT by jmyrlefuller ("The Price is Right has given away more money than anyone except welfare"-- Bob Barker)
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To: Red Badger
Local gravity may have changed slightly..............

I'm not sure if your comment is serious or not, but that's not possible. The scale measured the relative weight of two cylinders and that should stay constant regardless of any hypothetical change in gravitational pull.

44 posted on 09/12/2007 3:07:31 PM PDT by Alter Kaker (Gravitation is a theory, not a fact. It should be approached with an open mind...)
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To: decimon

Global warming is causing it to evaporate.


45 posted on 09/12/2007 3:07:34 PM PDT by puroresu
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O-16 and H-1... wonder why the O-16 got dropped?


46 posted on 09/12/2007 3:08:18 PM PDT by jmyrlefuller ("The Price is Right has given away more money than anyone except welfare"-- Bob Barker)
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To: Red Badger
Local gravity may have changed slightly..............

Hm. True. Never thought of that. :)

47 posted on 09/12/2007 3:09:01 PM PDT by Recovering_Democrat ((I am SO glad to no longer be associated with the party of Dependence on Government!))
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To: Captain Rhino
Slow release of gases entrained during the original casting process?

Ah, another plausible idea. Good, Rhino. (Why did you ever choose THAT name?) :)

48 posted on 09/12/2007 3:09:47 PM PDT by Recovering_Democrat ((I am SO glad to no longer be associated with the party of Dependence on Government!))
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To: decimon

Radioactive impurities decaying over time?


49 posted on 09/12/2007 3:10:03 PM PDT by lesser_satan (FRED THOMPSON '08)
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To: decimon

That’s what you get when you base all of the world’s measurements on the French Enlightenment.


50 posted on 09/12/2007 3:10:12 PM PDT by Cicero (Marcus Tullius)
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