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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?
how're you going to work with slugs in cgs or mks?
To go from inch-pound to mks, convert slugs to kg (1 slug = 14.594 kg), and pounds to newtons (1 lb = 4.448 N).
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.
Pity they can't make a perfect sphere of 1 kg of diamond. Diamond has, I think, a less complicated chemistry to take into account. At least I never heard of diamond surfaces oxidizing.
-- Cheers!
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?
Messages to/for me ( in me journal )
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.
Mass and energy are one and the same. We already have the Plank's constant, time unit (seconds) and an exactly definable unit of energy (h*1Hz.) Speed of light is also fixed. So equvalent mass of some number of photons with 1Hz frequency can define mass in terms of other constants. This has the advantage of not being tied to accuracy of atomic measurements.
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.
Their reasons are right there in the article.
Given a specific amplitude at a specific frequency (such that the length along the wave divided by the frequency is equal to pi), you'd have a pi length (over half a wavelength -- determined by measuring for (eg) 5 seconds of a 10 second frequency -- of a standing wave (which may be experimentally ideal)). All you'd need to do is determine the equation that would relate power input to frequency. You could then (using a fixed amount of power, or a fixed frequency) determine pi (assuming you could measure along the length of the wave). I have no idea whether this is feasible, or not, but kind of doubt it.
This is circular derivation, but then so is the silicon sphere. It also assumes the ability to measure in a non-discrete space-time (unless you're really lucky) as there would be differing real pis in a discrete space-time (color dependent speed of light, etc...). It may be possible to use light or sound as the wave carrier.
This is sort of on and off topic at the same time.
Anyone know of any good books about the history of measurement?
Like what came when and how things like horsepower or slugs and pounds came into use and how they originated?
I know about how stuff works type webpages, but I'm looking for a book with indepth info about English-Metric and whatever systems there used to be.
Thanks!
The Avogadro Project's web page calls the CSIRO the "Council for Scientific and Industrial Research". This is incorrect. The CSIRO's correct name is the "Commonwealth Scientific and Industrial Research Organisation".
in other words, I DID read the thing, and they're using nitrogen-doped-silicon to suppress, what was it ? spiral .. swirl defects, so the sphere isn't pure crystalline silicon, to begin with, AND...
they're measuring it by diameter, which isn't, I'd a' thought, the perfect way to discover how many atoms are in the object, and
they're using IT as a reference, so therefore they are using the object as a reference, so changes in mass ( due to some infinitesimally teensy amount being acquired-from or lost-to its cradle ) could affect it, hence my original assumpion that fluorine-sealed diamond would be the ideal tray-surface to hold the thing on ( hence my assumption of non-spherical-form'd be practically best ).
I give up...
I was wrong to have thought or questioned.
They Know[tm]
Cheers.
Messages to/for me ( in me journal )
Is this more than a handful or less?
I'm no physicist, but ok imagine a liquid sphere in space where all forces (gravity, etc) are equal around the sphere. The sphere would have to maintain perfect symmetry in respect to it molecular/atomic structure, otherwise there would be movement, which would mean non-perfection, because the blob moves. Isn't that how the big bang theory works in regards to the formation of galaxies -where imperfections --> globs of matter --> galaxies? So then can you stack a series of balls such that you end up with a perfect sphere - I would guess not, especially if number of balls = small. But then as n grows, we approach a point in which it approximates perfect. So to make this long winded question finally stop for crying out loud, is there in fact a point in which that size of n renders the forces surrounding the sphere inconsequential such that it effectivly becomes perfect?
-- (Score:i, Imaginary)
Soon after it's finished, a big rock-eating lasagna-with-plenty-of-sauce comes wiggling out of a tunnel, headed straight for the first guy it sees wearing a red shirt. Then it burns the message "No Kill I" on the ground, but after noting the quizzical looks on everyone's faces, and no Spock doing a mind meld on it and screaming, "Pain!" it stops, says, "Er, sorry. Wrong universe," and heads back in the other direction.