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Exactly One Kilogram Of Silicon
Ed Pegg Jr writes "You may know of the importance of 299792458
for length, and 9192631770 for time. However, the official standard for weight is still a block of platinum/iridium made a hundred years ago. A group of scientists from the Avogadro Project are hoping to change that, though, by producing a perfect sphere of ultrapure silicon."
A perfect sphere would imply fractional quarks and fractional parts of quarks, and ... an infinite precision!
Pi is still irrational, isn't it?
Don't tell me the all my math teachers lied to me!
What exactly is the benefit of having an object with a mass of exactly one kilogram if we already know, mathematically, how much one kilogram is?
I'm tired of reassuring the coding standards people that, yes, such-and-such a pointer has been tested against the platinum/iridium void* kept in a vault in Paris.
You cannot apply a technological solution to a sociological problem. (Edwards' Law)
producing a perfect sphere of ultrapure silicon
Pam Anderson has already cornered this market.
Ohhhh, silicon...
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We'll come up with our own standard of mass, and we'll call it the Freedom Sphere. So put that in your pipe and smoke it, Jacques Chirac! With your burned lips!
the SI unit for length is the metre - not the kilometre
why is the unit for mass the kilogram when it should more logically be the gram?
using the gram might be easier to accurately measure too.
Get in here this INSTANT, and bring it with you! When your father gets home you are going to be grounded, young man! Two weeks to the PICOSECOND by the atomic clock in the kitchen. Now go stand in the corner, and NO LEANING! You'll probably throw the wall out of plumb, or expand the angle to 90.7632+1E degrees or something, you troublemaker!
ITYM mass. SI has no unit for weight. There's the newton for force, but it is not defined in terms of gravity. It is also not a SI base unit.
But then again, I could be wrong.
I've always have this strange idea of a Austin Powers movie where DR EVIL has stolen the "Kilogram" and held the entire world hostage for one trillion pesos.
What an idea.
1/10^7 of the distance from Paris to the North Pole,
Actually, the meter was defined as roughly 1e-7 of the distance from the equator to the North Pole along Paris's meridian, making the earth roughly 4e7 m (40,000 km) around.
Will I retire or break 10K?
Warning: Pregnant women, the elderly and children under 10 should avoid prolonged exposure to Happy Fun Silicon Ball.
Discontinue use of Happy Fun Silicon Ball if any of the following occurs:
- Chipping
- Scratching
- Spontaneous degeneration
- Conversion from matter to energy (E = mc^2 = c^2 energy!)
- Sudden change in mass of everything around you
Happy Fun Silicon Ball has been shipped to our troops in Kuwait and is also being dropped by our warplanes on Iraq. Our Westernization process of SI imperialism will defeat them!When not in use, Happy Fun Silicon Ball should be returned to its special container and kept under refrigeration...
Do not taunt Happy Fun Silicon Ball.
Happy Fun Silicon Ball
Accept no substitutes!
We recently had heard in the office over one of the Yellow Machine that's made by Anthology Solutions.
Is there some inherent problem with other geometries?
Like, say, the cylinder ( as the original kilogram were )
Isn't machining a sphere, perfectly, more .. error-prone?
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I always thought one kilogram is one liter of pure water?
If I'm correct what is the point? They should worry about what makes a liter and what is pure water.
-- I don't buy it, I grow it.
Water expands and contracts as the temperature and pressure around it change, even in the range where it is still liquid.
It turns out that liquid water at 1 atmosphere pressure is most dense at about 4 degrees Centigrade, where its density is 0.9999750 g/cm^3. at closer to room temperature- at 22 degrees C- its density is only .9977735 g/cm^3. It never actually gets up to 1 g/cm^3 the unit system was originally designed to use, I think because of the limits of accuracy of measurements when the current definitions of individual units were set. In defining a unit, all those significant figures are relevant, so for these purposes the above are unacceptably big differences.
Measuring mass by what the volume of water is would be more complicated and less accurate than the current system. Besides, a liter is trickier to define than a kilogram, so it'd likely be the other way around if defined in terms of each other.
Secondly, it doesn't matter either what exactly is 1 kilogram. what matters is some reference atomic mass and then pick up Avogadro number (based on existing 1 kilo mass) and then get rid of the existing standard. this would allow independent reproduction (e.g. 1 kg is equivalent of 6.02...... x 10^23 atoms of Oxygen 16 in certain energy state. this scheme too has problem. there is no practical way of verifying that you have met the standard definition. so, two scientists can argue that each is possesing exact 1 kg and this cannot be arbitrated.
Not only do diamonds' surfaces oxidize, they're pretty easy to burn, and only metastable in any case.
Diamonds are *not* forever.
A good question. The reason is that a kilogram is not a mathematical object (which is pure idea). It is a scientific object (which can and should have a real world representation).
Pi does not exist in the real world. If you don't agree, show me an object in the real world that has exactly pi length, weight, or volume.
By contrast, the kilogram is an idea (an agreement really), that leads to a real world object (bar of platinum, sphere of silicon) that people can test their measuring devices against.
Ask yourself this: if you and your friend had two scales, how would you know which one is more accurate?
Answer: you would test them against a scale you agreed was more accurate.
But, in order to test for accuracy, you need a very "accurate" object. You need something that everyone agrees weighs a certain amount (say a kilogram?) And your "most accurate" scale had better exactly weigh that object as exactly one kilogram.
That's basically what calibration is: you take an object you declare to be 1 kg (or 1 g) and then you set your scale to indicate it as such. Obviously, there is more to it than that, but that's the very basics.
Science relies tremendously on these types of standards. One of the biggest (and unsung) "wins" of the 20th century was the tremendous increase in the objective standards of accuracy. Imagine trying to build a microprocessor if everything was designed in terms of hand lengths or feet lengths of the various contractors. Without increasingly tight, objective standards of measurement, modern science and technology would not exist.
Ironically enough, I'm a mathematician. I would encourage you to talk to a professional scientist or engineer and ask them about it.