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Old 03-17-2009, 11:56 AM   #1
Coign
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Mar 18, 2009: Even rounder thing

Not to overshadow Bruce but while trying to figure out how you make a perfect sphere I found a site where they do that.

And to spoil the surprise...

you grow it.





http://www.csiro.au/news/PerfectKilo...iaRelease.html

Quote:
While a physical object will still be necessary for calibrating scales and balances, the silicon atoms in the sphere will always remain the same. It is for this reason that the scientists working on what’s known as the Avogadro Project are collaborating to determine what is effectively the number of atoms in a sphere. Once the number of atoms is known, the definition of the kilogram can be based on it from then on.

The best sphere the ACPO team has made had a total out-of-roundness of 35 nanometres. That is, the diameter varies by an average of only 35 millionths of a millimetre, making it probably the roundest object in the world.
Quote:
It has taken three years to produce the 20 cm long cylinder of silicon. The special silicon, known as monoisotopic silicon, was made in Russia and grown into a near perfect crystal in Germany. It will take something like twelve weeks to make one sphere 93 mm in diameter (the team will make two).
And some more current info.

http://www.csiro.au/science/ps35k.html

Quote:
OUTCOMES
On Friday 4 April 2008, these two spheres were presented to representatives of the Avogadro project.
Now it's up to these countries, and others in this major international effort such as Italy, Belgium, Japan and the US, to determine what is effectively the number of atoms in a sphere. Once the number of atoms is known, the definition of the kilogram can be based on it from then on.
Click this link for some more pictures including a rough look at the sphere.

http://www.acpo.csiro.au/avogadro.htm

And some very detailed information on where the scientific community is at on defining/redefining the mass of a kilogram. For right now it seems that the silicon sphere is not the standard and that they still use the old platinum/iridium weight as the International Standard.

http://www.bipm.org/en/scientific/mass/faqs2_mass.html
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Last edited by Coign; 03-17-2009 at 12:19 PM. Reason: Adding in more info on why
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Old 03-17-2009, 12:41 PM   #2
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it's SCIENCE!

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Old 03-17-2009, 01:12 PM   #3
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If the scientists can learn to make them smaller, they can play a perfect game of Chinese pinball.
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Old 03-17-2009, 02:56 PM   #4
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All this talk of balls is making me hungry.
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Old 03-17-2009, 05:59 PM   #5
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Wow, for once something reflective was posted without the obligatory naked-guy-with-a-camera reflection.
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Old 03-17-2009, 10:25 PM   #6
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Quote:
Originally Posted by Coign View Post
you grow it.

They grow a cylinder and cut grind and polish it down, pretty much by hand.

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Old 03-17-2009, 11:58 PM   #7
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Tomorrow's IotD ... Roundestestest object evah ......


LUMBERJIM!
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Old 03-18-2009, 12:34 AM   #8
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Cool, thanks Coign.

I'm confused, the first link says;
Quote:
The best sphere the ACPO team has ever made had a total out-of-roundness of 35 nanometres. That is, the diameter varies by an average of only 35 millionths of a millimetre, making it probably the roundest object in the world.
And the second link says;
Quote:
The roundness delta of the finished sphere (being held above) is about 50 nm on a 93.6 mm diameter. It is believed to be the roundest object in the world.
These technical writers seem be pretty cavalier about claiming, "roundest object in the world'.

Yesterdays balls were round within 40 atomic layers, and I have no idea how to compare nanometers to atomic layers. I suppose it would make a difference what material it was 40 atomic layers of.
Anyway, my balls ain't round.
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Old 03-18-2009, 05:54 AM   #9
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A nanometer(nm) is 0.000,000,001 meters.
An Angstrom is 1/10 of a nanometer. A silicon crystal has a nucleus to nucleus spacing of 5 Angstroms. Or 0.5nm.

So an "atomic layer" is about 0.5nm.
40 atomic layers ~ 20nm.
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Old 03-18-2009, 07:16 AM   #10
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Quote:
Originally Posted by xhaos01 View Post
Wow, for once something reflective was posted without the obligatory naked-guy-with-a-camera reflection.
If you look real close, you will see the camera guy grabbin' his balls.
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Old 03-18-2009, 09:09 AM   #11
birdclaw
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makes the time i drew that perfect circle seem lame in comparison.
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Old 03-18-2009, 09:44 AM   #12
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Quote:
Originally Posted by Beest View Post
They grow a cylinder and cut grind and polish it down, pretty much by hand.
Cool thanks Beest. I had seen most of those pictures while looking on how they did it but that video added some new ones and put it all together.

And to Spuck and Bruce, if the Gravity guys didn't get their measurements wrong than the balls Bruce found would actually be rounder than the Silicon weight ball so Bruce's post is still rounder.
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Old 03-18-2009, 10:46 AM   #13
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Quote:
Originally Posted by xoxoxoBruce View Post
Cool, thanks Coign.

I'm confused, the first link says;

And the second link says;
Ah, but, it doesn't say this ball is that ball (the roundest one they ever made)
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Old 03-18-2009, 10:53 AM   #14
xoxoxoBruce
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Quote:
Originally Posted by SPUCK View Post
A nanometer(nm) is 0.000,000,001 meters.
An Angstrom is 1/10 of a nanometer. A silicon crystal has a nucleus to nucleus spacing of 5 Angstroms. Or 0.5nm.

So an "atomic layer" is about 0.5nm.
40 atomic layers ~ 20nm.
Thanks Spuck. Walks away, head spinning, at the amazing depth of knowledge on this board.
Quote:
Originally Posted by Coign View Post
And to Spuck and Bruce, if the Gravity guys didn't get their measurements wrong than the balls Bruce found would actually be rounder than the Silicon weight ball so Bruce's post is still rounder.
Maybe... the writers of all these links don't sound like the scientists/technicians that are actually doing this amazing shit, and the differences are in the virus' eyelash range.
The idea of making anything, any size, and knowing exactly how many atoms it contains... paging Gene Roddenberry.
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Old 03-18-2009, 11:01 AM   #15
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Quote:
Originally Posted by SPUCK View Post
A nanometer(nm) is 0.000,000,001 meters.
An Angstrom is 1/10 of a nanometer. A silicon crystal has a nucleus to nucleus spacing of 5 Angstroms. Or 0.5nm.

So an "atomic layer" is about 0.5nm.
40 atomic layers ~ 20nm.
0.54 nm is the lattice parameter, not the nucleus to nucleus distance of adjacent atoms .
It's probably what they meant by 'atomic layer' but not technically correct.
The Gravity Balls were quartz, lattic parameter 0.49 nm.

X-ray diffraction is my main occupation now, I can do a 'can you tell what it is yet' of diffraction patterns if you like.
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