Posted on 06/14/2007 10:36:36 PM PDT by anymouse
They will be the earth's roundest spheres, crafted by Australian scientists as part of an international hunt to find a new global standard kilogram.
Ever since scientists discovered that the current standard -- a bar of platinum and iridium held in a French vault since 1889 -- was slowly deteriorating, the search has been on for a replacement.
Using a single crystal of silicon-28 grown by Russian and German scientists over three years, a team of Sydney scientists and engineers will grind and polish two silvery balls, each weighing precisely one kilogram, with imperfections of less than 35 millionths of a millimeter.
"We are doing everything to really create a perfect object. It's not only near-perfect in roundness, but also the crystal purity, the atomic species and so on," project leader Walter Giardini told Reuters on Friday.
"Silicon is a very nice material to use that we understand well, makes good crystals and can be worked," said Giardini, from Australia's National Measurement Institute.
The two balls will take 12 weeks to create and, because they are made from a stable element, they will not fall victim to moisture, corrosion and contamination like the current kilogram standard, known as the International Prototype.
The spheres will be a step along the perfect kilogram road, with the project's ultimate aim to re-define the kilogram in terms of numbers of atoms, rather than an object open to damage from earthquake or environmental changes.
"The aim is not to change the value of the kilogram, but to ensure its stability for all future times," Giardini said. "It will no longer depend on an actual physical object and this is going to allow us to relate the mass to the individual atoms."
The project is a collaboration involving scientists from Russia, Germany, Italy, Belgium, Japan, the United States and Australia, in cooperation with the International Bureau of Weights and Measures.
On completion, the spheres will be measured for volume in Australia, Germany and Japan, then measured for mass. Belgian scientists will look at the molar mass of the crystal used to calculate the number of molecules in each sphere.
Australian scientists have the most expertise in grinding near-perfect spheres, having been turning them out for clients including NASA since the early 1990s.
"We have developed technology so that we can see what we are getting, whether they are slightly oval or flat. We are trying for an accuracy of two parts in 100 million," Giardini said.
Come on now guys, this is serious science. ;)
The RNC is looking for donations.
They could certainly make do with those.
Maybe I missed something. Why are they making them as “perfect” spheres? Seems like a lot of wasted effort that serves no purpose other than to say look what we did.
The part they didn’t tell you is that John McCain has commissioned this project, he would like to fidget with the balls in his hands, he claims he can feel the imperfections in the steel balls he currently fidgets with.
For the first time in over a century, europe will be in possession of a pair of balls.
They bloody well better make sure those two are perfect, it’ll be many a year before the euros find another set of balls to replace these with.
Serious? Well, depending upon where on earth this ball is weighed (was it milled down in Paris by Aussies, or milled down in Autralia?), it will be more or less than exactly the weight it was milled to originally. Of course, if kept in Paris it is never going to be safe anyway ...
Making them spherical gives them a predictable volume. Since they know the isotope used and its density, knowing the exact volume tells you the exact mass of the sphere.
“The Grind’s Almost Over to Forge two Perfect balls”
Someone ask Hillary, I think she can help.
Europe? I had the impression from the preceeding post these balls were being fashioned for John McCain as his were imperfect.
Maybe they can make a second set for McCain.
The RNC only accepts pesos.
On second thought, these one kg.silica balls will undoubtedly be too big for John McCain.
Maybe AC/DC can use them.
You jest. The RNC would be afraid of a real set....
As warped as he is though, not even a new perfect pair will help him achieve balance.
The RNC had a set, but Hillary’s got ‘em...
But a cube would be even more exacting, since the volume of a cube is LxWxH, and since L, W, and H can be rational numbers, you can have a volume that's a rational number. However, when you're dealing with something that's got a circular component, now you're adding an irrational number (pi) into the computation, and while the volume is going to be a finite number, it will still be irrational, and therefore somewhat less exact (on an infinitesimal level).
Mark
They are not measuring for weight but rather for mass. Weight is relative, mass is a constant.
Couldn’t a gadget be made to actually count individual atoms into a single mass? Then when it’s counted off a few quadrillion or so, we have something we can weigh.
Hmmmm, you know I think this was attempted a few times on the corners of 17th St and Castro in San Francisco, but with mixed results.
Probably wouldn’t need a quadrillion to get a ‘standard’ ... time is already standarized by a vibrational wavelength isn’t it?
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