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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
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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. |
| 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). |
http://www.csiro.au/science/ps35k.html
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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. |
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
lumberjim Tuesday Mar 17 01:41 PM
it's SCIENCE!
newtimer Tuesday Mar 17 02:12 PM
If the scientists can learn to make them smaller, they can play a perfect game of Chinese pinball.
Sheldonrs Tuesday Mar 17 03:56 PM
All this talk of balls is making me hungry.
xhaos01 Tuesday Mar 17 06:59 PM
Wow, for once something reflective was posted without the obligatory naked-guy-with-a-camera reflection.
Beest Tuesday Mar 17 11:25 PM
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Originally Posted by Coign
you grow it.
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They grow a cylinder and cut grind and polish it down, pretty much by hand.
ZenGum Wednesday Mar 18 12:58 AM
Tomorrow's IotD ... Roundestestest object evah ......
LUMBERJIM!
xoxoxoBruce Wednesday Mar 18 01:34 AM
Cool, thanks Coign. 
I'm confused, the first link says;
| 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. |
| 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. |
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.
SPUCK Wednesday Mar 18 06:54 AM
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.
4fingermalone Wednesday Mar 18 08:16 AM
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Originally Posted by xhaos01
Wow, for once something reflective was posted without the obligatory naked-guy-with-a-camera reflection.
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birdclaw Wednesday Mar 18 10:09 AM
makes the time i drew that perfect circle seem lame in comparison.
Coign Wednesday Mar 18 10:44 AM
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Originally Posted by Beest
They grow a cylinder and cut grind and polish it down, pretty much by hand.
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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.
Beest Wednesday Mar 18 11:46 AM
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Originally Posted by xoxoxoBruce
Cool, thanks Coign.
I'm confused, the first link says; And the second link says; |
xoxoxoBruce Wednesday Mar 18 11:53 AM
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Originally Posted by SPUCK
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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Originally Posted by Coign
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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The idea of making anything, any size, and knowing exactly how many atoms it contains... paging Gene Roddenberry.
Beest Wednesday Mar 18 12:01 PM
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Originally Posted by SPUCK
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. |
.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.
xoxoxoBruce Wednesday Mar 18 12:06 PM
Another one... youze guys are giving me an inferiority complex. 
| I can do a 'can you tell what it is yet' of diffraction patterns if you like |
dar512 Wednesday Mar 18 12:10 PM
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Originally Posted by xoxoxoBruce
Walks away, head spinning, at the amazing depth of knowledge on this board.
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Wombat Wednesday Mar 18 05:59 PM
So shiny. They missed the perfect opportunity for some reflectoporn.
classicman Wednesday Mar 18 06:58 PM
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Originally Posted by dar512
the next time that happens would mind taking a video? I think it would be entertaining.
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DanaC Wednesday Mar 18 07:23 PM
Oh nice link Classic. One of my all time favourite movies.
Shawnee123 Wednesday Mar 18 08:25 PM
Oh hail no, classic! That was awesome. I also saw that movie in the theater when it came out and had no idea that was coming. My friends and I were freaking out and loving it.
It still ranks in one of my all time wtf movie moments.
xoxoxoBruce Thursday Mar 19 01:43 AM
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Originally Posted by dar512
Hey Bruce, the next time that happens would mind taking a video? I think it would be entertaining.
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Originally Posted by Wombat
So shiny. They missed the perfect opportunity for some reflectoporn.
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