From the Wall Street Journal – By JEANNE WHALEN
In a vault beneath a 17th-century pavilion on the outskirts of Paris sits a platinum cylinder known as Le Grand K. Since 1889 it has been the international prototype for the kilogram, the standard against which all other kilos are measured.
But over the years, scientists have noticed a problem: Le Grand K has been losing weight. Weigh-ins at the International Bureau of Weights and Measures show that the bar has shed approximately 50 micrograms—roughly equal to a grain of sand.
The problem has vexed scientists who monitor the kilo the way tabloids track the waistlines of Valerie Bertinelli and Kirstie Alley. The stakes, however, are weightier.
“It’s a scandal that we’ve got this kilogram hanging around changing its mass and therefore changing the mass of everything else in the universe!” Bill Phillips, a Nobel Prize winning physicist, exclaimed at a scientific summit in London this week. No one knows for sure what went wrong with Le Grand K, but some theorize it lost weight from being cleaned.
Dr. Phillips and other mandarins of metrology were gathered at Britain’s Royal Society to debate an urgent question in the science of measurement—how to re-define the basic unit of mass, as well as other measurements such as the second, ampere, kelvin and mole.
The aim is to tie each to a widely accepted property of nature, rather than to a lump of metal or some other imprecise benchmark. The meter, for instance, was once measured as the distance between two notches on a metal bar. It is now defined as the distance light travels in a vacuum in 1/299,792,458 of a second.
The new definitions are “as big a change as the introduction of the metric system during the French Revolution,” says Terry Quinn, a dapper Briton who organized the seminar and once served as director of the International Bureau of Weights and Measures, which ensures world-wide uniformity of measurements. Frequent clashes about the best approach mean the temperature of debate has at times “risen quite high,” he added, without specifying by how much.
Full story at the Wall Street Journal
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Could the measured “weight” of the grand kilo be affected by volcanic eruptions?
Anthony, you should consider changing the title of this blog entry because its not certain that the grand kilo is losing “mass” .. it could be something else.
The metre is now the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second (with or without a gravity field?). A second is no longer connected to the length of a day and its sub-divisions but is now the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom at rest at a temperature of 0 K.
By 2015 the kilogram could be related to the Planck constant where the numerical value of the Planck constant will be fixed.
(A side issue is that if THE Standard kilogram is by definition a kilogram then it cannot – by definition – be losing mass – everything else must be gaining!!!!)
A long way from the days of Edward I when a Yard was set by the “Iron Ulna of our Lord the King”. All of this is no doubt a great advance and necessary but I have difficulty to relate to the new definitions. I cannot invoke any image of 9 192 631 770 periods of a radiation or the 299 792 458th part of a second and I feel that something is being lost……
Once again, it’s the “saucer people”. After their tankers dump their snow load and before they pick up our sea water for their return trip home, the crews take a short R&R. They sneak in under cover of darkness and LICK that chunk of platinum with their sand-paper, cat-tongues. Gets ’em high as a kite. The promise of a “platinum lick” is a big recruiting tool down at the saucer-crew union hall.
@DocattheAutopsy says:
January 28, 2011 at 7:06 pm
“…it is reasonable that 50 micrograms of helium would be lost from the sample from alpha emission….”
Ahh, that would be “cold diffusion” then.
But seriously, you may have a point.
Mooloo says:
January 28, 2011 at 7:54 pm
The resistance of the US to a convenient and international system is nothing to be proud of. It’s like those people proud of being illiterate – because they’d never seed the point of book lernin.
Well, it’s always hard to trace something like that down to a single reason, but if your argument rests on calling your intended new partners a bunch of illiterate hicks, it’s not a *terrible* shock they didn’t flock to your side in the debate.
If you were an ambassador, I’d bank on a war comin’.
55 micrograms of platinum is worth about 0.17 cents, which would be lost in the roundoff error nowdays, but prior to 1960 it would’ve been around 84 centimes (the French changed the franc in 1960 to be worth a hundred of the old francs, so an old centime is 0.0001 new francs). The detectives working this case should simply compare the value of platinum in French or Swiss francs over the years (this thief is extremely clever, so the money is probably going into a Swiss bank account) and look for unexplained bank deposits of that amount.
Meanwhile it’s time to stick their kilogram in a vacuum chamber and deposit another 50 micrograms on it.
fhsiv says:
January 28, 2011 at 6:40 pm
Is the force of gravity changing at that location?
________________________________
Have the French lost some of their “Gravitas”?
Chris Reeve,
Could you contact me please? Try aignews at fastmail.com.au
I cry Foul !!!!
I’ve been on this diet for years – and now all my efforts are in vain – weight increase and I didn’t even get to enjoy it!!!!!
Why would they be cleaning it in the first place ? It appears to be stored under vacuum in multiple layers of Bell jars. How exactly does it get “dirty”?
Smokey says: January 28, 2011 at 5:08 pm
Measuring mass at the microgram level is much more difficult than it would seem. Mass is often confused with weight, but they are not the same.
The problem was that they measured local gravity with the GRACE satellites.
Michael says:
January 28, 2011 at 7:05 pm
I thought a kilogram was defined as the mass of a litre of water.
A litre is the measurement of volume and so it’s mass is a variable dependent on temperature or pressure.
You flippant commenters do not appreciate the gravity of the situation.
The implications of this scandal are massive!
How long must we weight before someone decides to take action?
….
I’ll get me coat! 😉
Well, that’s another fine mass we’ve gotten ourselves into…
Missing mass? Perhaps it’s hiding in the ocean. It’s a trenberthy.
Its great to read the comments on WUWT there is more humor here than anywhere else on the web. I can’t stop laughing at some of the comments, even though they carry serious scientific comment along with them. Well done !!
“Several dozen copies of the original are stored at national laboratories around the globe. Once every 50 years or so, scientists carry the copies by hand to Sèvres, just outside Paris, in little boxes, to compare them to the original. At the most recent summit in 1989, they noticed that the kilos differed by an average of about 50 micrograms. This is often described as Le Grand K losing mass, though to be precise, it’s possible that the copies had gained mass.”
It is curious that it differed to all copies and the *average* was 50 µgrams, not that it was off by 50 µgrams to all of the copies. Stored at national labs huh?
It’s just that if I wanted to store a block of matter and be absolutely sure that nothing under control could possibly affect it’s mass I’m positive I would not choose a high-energy research national laboratory to store it during the fifty years of the most intense nuclear experiments. What were they thinking?
This must be why the bathroom scales say I’m getting heavier.
I knew my fruit and veg purchases were feeling suspiciously light of late. Vindication! 😀
It’s worse than we thought! Le Grand K
Is steadily wasting away.
My mass, then, gets greater?
Let’s massage the data,
And hide the incline. That’s the way.
When you measure something, allways measure three times. Because nothing is easier than fooling yourself during the process. My bet is on the measuring equipment being a bit “out”.
Question: How do they perform a calibration of the measuring device? Now, thats a good one, dont you think?
On the funny side I collected the following possibilities from the commenters here;
-It is converted to Dark Matter. ( It doesn’t matter, does it?)
-Heisenberg farted somewhere in the room. (You cannot see it, but it is there, somewhere)
-The GRACE satelite passed over it, and its pulling force lightened it.
-NOAA and GISS adjusted and homogenized the statistical results.
-Cold fusion converted some mass to gravitons and hydrinos.
And perhaps;
-It was measured in lbs, and converted to Kg using a super duper computer.
-A French Aristocrat lost some perfumed powder on it from his whig.This contained
a radioactive powder called Curiositum, which is now decayded into mediocrecum.
This reminds me of the old story about a Mechanical Engineer, a Civil Engineer and a Physicist arguing about in a bar whose work was most accurate. The Mechanical Engineer was used to measuring to the nearest micron. The Physicist airily pointed out that when he measured distance it was how far light travelled in an infinitesimal fraction of a second. The Civil Engineer took a swig of his beer and pointed out that when he was building something he didn’t allow for error at all. He always checked through his theodolite and gave a thumbs up when it was absolutely “spot on”!
(Needless to say, I’m a Civil Engineer.)
Infamous British joke.
English salesman to mystified French buyer: “Of course we quote the weights in pounds & ounces. Avoirdupois is your lingo, isn’t it?”.
The word avoirdupois is from Old French aveir de peis (later avoir de pois), literally “goods of weight”.
http://en.wikipedia.org/wiki/Avoirdupois