The international kilogram conundrum[Weights have mysteriously fluctuated]

LA Times ^ | 17 Apr 2008 | Jia-Rui Chong

[Freedom4US]

The nice thing about standards is there are so many to choose from. How many troy ounces in a kilogram? Figure platinum is what, 2000 an ounce?

A fellow could have a pretty good time in Vegas with that thing..

[Leo Carpathian]

Gimme pound of bacon, liter of Tequila and Million $$$ gummit grant and I will figer it outttt! Hickkkk!

[Nathan Zachary]

"The ID response to this would be to simply state that the designer changed what it weighed and that no further research would be needed."

uh, no, it would be something like mine.

However,The evolutionary explanation would be that it's evolving into something else.

[300winmag]

In the more than a century since No. 20 and dozens of other exact copies were crafted in France to serve as the world's standards of the kilogram, their masses have been mysteriously drifting apart.

My first question would be, how "exact" were the copies by the technology of the day? Same proportion of isotopes? Same batch of metals? Were allowances made for environmental effects of the measuring instruments made?

In the past 100 years, how many different instruments were used to measure the copies? Again, were any allowances made for new sets of inaccuracies of the new instruments?

I think we need a yearly weigh-in on all the kilograms, done with the same instrument, and the same person. We'd have a much better handle on things after about 20 years of more detailed data.

If they'll cover my first-class travel and accommodations and a decent per-diem, I'll happily travel all over the world all year long to measure those cylinders. But I think I can save them some money if they just wet-lease a Gulfstream G5 for me. That way I can travel just like your average liberal.

[lafroste]

My hunch is the universal gravitational constant isn’t.

Amen to that. Maybe I'm not so nuts after all. See my tagline.

[Politicalities]

But isn’t the interesting thing that we thought we had sealed these objects in a way that would prevent them from changing mass, and yet they seem to be changing mass, and in different amounts?

Meh. To me, it just doesn't seem like that much of a mystery. Every single man-made process involves tolerances, and when these things were manufactured (and, I suspect, today) we were unable to count the individual platinum atoms that were going into them. We can't make a perfect vacuum, and we were probably less able to make a perfect vacuum back when the prototypes were being created. I'm sure there were quite a few errand molecules floating around in the near-vacuum surrounding each kilogram, and some of them probably settled on them, nestling in interstices between platinum atoms. And remember, we are talking about (in the case of the U.S. kilogram), a difference of 19 parts in a billion

Like ko_kyi, I am far readier to believe that this discrepancy is due to the inevitable imperfection of human manufacturing, storage, and measurement processes than some fundamental flaw in scientific theory.

[HP8753]

They should have put reeded edges on all the samples...
Just like old American gold and silver coins.

With the price of platinum up, Maybe some of the keepers have been shaving them for profit.... ;-)

[tokenatheist]

the evolutionary response would be that the mass isn’t living so evolution doesn’t have a thing to do with the changes.

[lafroste]

How could a standard weight fluctuate?

Easy. Gravity fluctuates.

[tet68]

I remember watching footage of the lunar lander in orbit around the moon shot from the command module, it was jinking all over the place and the narration said it was because of gravitic anomalies.

[coloradan]

I suspect it has to do with cleaning methods, which have accumulated errors over the decades. (Look at when the comparisons were made: three times since manufacture 1889, 1950, and 1990.

[coloradan]

When they are compared, they are in the same room and therefore subject to the same gravitational field.

[dljordan]

It’s a case of quantum fluctuation induced by cosmic rays obviously. Scientists my hairy......

[coloradan]

Note that Le Grand K doesn’t fluctuate. Only the other copies do.

[Nathan Zachary]

"Also note that different locations over the globe have dfferent gavitic constants - theu, if we have a “known” mass and the gravitic constant for that particular region of the globe changes, that sample no longer “weighs” 1 KG. Does that make sense?

Certainly. Also, the earth is loosing it's wobble ever so slightly each year as well, and it's orbit around the sun changes slightly year to year. All these things can have slight positive and negative effects, adding up to a net loss of gravitational density.

You wouldn't think that this is so baffling to these Kilo protectors, but maybe they are too busy to give it much thought... or aren't qualified to do so.

[ConservativeMind]

Oh, yeah, knowing a different unit for length or weight has most definitely put us at an absolute disadvantage in sciences here in the US.

NOT! Big hairy deal. It doesn’t make one illiterate or less capable using a different unit.

[tomkat]

lol    

[OeOeO]

Global gravitational evaporation is REAL.

WE NEED TO DO SOMETHING NOW, before the polar bears and rainforests float away.I just need something to blame it on. Honest! I can prove it. I just need a million dollar grant and some nobel prize money.

[CodeToad]

"the pound is defined in terms of the kilogram, you blockheads" Actually, yes and no. Because the SI system was forced upon the standards community the definition of a pound is a measurement against the kilo, yet, the pound still exists as it has for centuries against the grain, exactly 7,000 grains per pound, a more meaningful definition than the kilo. The pound, defined as 0.453592338 kg, is a useless definition as no one here can possibly use an instrument that accurate.

In fact, the grain is the unit of measure for firearms, including gun powder and bullets, both measured as grains. Many other scientific sectors also use the grain. The kilo is a useless measurement and was nothing more than an abitrary measurement.

The metre or meter[1] (symbol: m) is the fundamental unit of length in the International System of Units (the SI). It was originally defined so that the land distance between Earth's poles and Equator would be exactly 10,000,000 metres; today, the way it is defined means the speed of light is exactly 299,792,458 metres per second [2].

I guess the Nautical mile wasn't known by those wishing to create yet another units of measure.