Posted on 06/14/2007 10:36:36 PM PDT by anymouse
Also, the sphere will be more "chemically" robust. That is, some of the chemical processes which would cause deterioration of the object will be acting at the surface of the object. A sphere has the minimum surface area possible for a given volume, thus minimizing the amount of deterioration at the surface.
I think you have a good point here. But a pure single-crystal silicon sphere is perhaps going to behave a lot like an aluminum sphere would behave. That is, a silicon-dioxide layer will probably form at the surface, perhaps penetrating some small depth into the sphere.
The resulting oxide layer will be relatively stable and will inhibit further oxidation, since oxygen will not readily penetrate the oxide layer.
It would not surprise me to learn that the fabrication will include oxidizing the surface.
Perfect balls ping.
(That might even be a complete sentence)
Thought problem/experiment:
Perfect spheres, of X atoms diameter = 1 KG mass + an excess of atoms such that removing the excess uniformly from the surface leaves the sphere massing 1 KG - 1/2 the number of atoms in the outer most layer needed to make the sphere 1 kg.
To grind, or not to grind? Grind ONE and leave one, then use both in tandem?
“The Grind’s Almost Over to Forge two Perfect balls”
That’s gotta hurt.
No doubt, the balls will be perfectly blue too.
Probably not. I suggested in post 62 that some surface treatment might be beneficial. The silicon-dioxide layer will be much harder than just a silicon layer, if memory serves, and thus more durable.
But the depth of any such chemical treatment will probably be quite small compared to the radius of the sphere. It would not surprise me if the difference was less than the ability to resolve the mass difference.
Stability of the sphere is probably more important than having exactly the requisiet number of silicon atoms. One could probably calculate the contribution of an oxide layer to the total mass and adjust the radius to compensate. But the adjustment might be quite small.
Once a targetted radius is calculated, it then becomes a chore to "grind" the sphere to proper size. Infra-red lasers might be used to measure many "diameters" and an averaging done to size the sphere properly.
In fact, a very useful check on the process would be to process each sphere and then compare their masses. Anything less than a dramatic agreement in the two masses would indicate variability in the fabrication process which would limit the final usefulness of the product.
There could still be systematic errors in fabrication which could bias both spheres in the same directions. These errors would be hard to spot.
It was the strawberries, the strawberries I saw. They laughed at me but I knew about the strawberries, I knew it I tell ya.
I think those spheres are made of nothing but Si atoms, linked in a crystal.
No O2 in there.
Infra-red lasers might be used to measure many “diameters” and an averaging done to size the sphere properly.
Bearing ball manufacturing grinds out millions of bearing balls per day that are spherical to within a few microns. These do not require a flat reference to manufacture, nor measure. Think beyond Cartesian coordinates.
At the level of precision desired in this case, how does one avoid measuring runout and imperfections of the bearing system?
I was thinking that maybe there was a way to measure a particular diameter from one side of the sphere to the other, in absolute terms of a certain number of wavelengths of some infrared standard.
Perhaps one can accomplish an absolute measure of diameter by fabricating a length standard first to calibrate the bearing system?
...until it is exposed to earth's atmosphere & moisture (humidity).
The gist of my statement is that easily Si reacts with O^2 to form oxides; that it is NOT 'non-reactive' as a certain ignorant keyboard jocky, who never studied any kind of technical subject beyond 6th grade general science, asserted.
Take a look at William Tell's #62 & #67.
IOW, it was a criticism of a journalist who does not understand what he was seeing & hearing, then presuming to educate his readers down to his own level of ignorance.
And jus thow many stones will this thing weigh again?
hahahahaha.
Ha ha ha
Well, it was either that or an inappropriate squirrel joke.
>>At the level of precision desired in this case, how does one avoid measuring runout and imperfections of the bearing system?
Hire technical experts. Anything is possible. Air bearings? A slightly larger cup filled with an oil film might do it.
>Perhaps one can accomplish an absolute measure of diameter by fabricating a length standard first to calibrate the bearing system?
Yes, you’d probably look for cyclic variations corresponding to the characteristics of the bearing system.
Sorry, but you’re going to have to explain how oxygen can get into a pure silicon crystalline matrix. It might stick to the outermost Silicon atoms (I’m unsure about that), but that would not be a factor in diameter or mass.
Yes, but it still depends on an “actual physical object”.
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