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Technische Universität Ilmenau and the Physikalisch-Technische Bundesanstalt (the National Metrology Institute of Germany) are developing a balance which is required for measuring the redefined kilogram that will be introduced in 2018. Called the Planck balance, this highly precise electronic weighing balance is not based on weights, but refers to the fundamental physical constant called Planck's constant. The balance will be used worldwide for calibrating other scales or balances so that they correspond to the system with this new method. The new balance will also be used in industry for measuring weights.
In many sectors, there is a significant demand for highly precise balances, including pharmaceutical companies for precise dosing of medical products, in official metrology service labs for calibrating scales for food, and in police departments, for the proof of toxic substances and in ballistics.
The original kilogram, a 4 cm cylinder made from platinum and iridium and stored under three glass domes in a safe near Paris since 1889, is becoming lighter. Over 100 years, it has lost 50 millionths of a gram. As all scales worldwide refer indirectly to this unique kilogram, they all weigh incorrectly, even if by minimal and negligible amounts. Although the original kilogram is becoming lighter, structurally identical copies of the prototype are used worldwide – which means that these copies are slowly becoming heavier relative to the prototype. Therefore, a new standard is required that does not change and cannot be damaged or lost.
In 2018, the new kilogram will be adopted at the 26th General Conference on Weights and Measures. It is not defined by an object or a physical mass, but by Planck's constant. The highly precise, continuously measuring Planck balance, developed by the German university Technische Universität Ilmenau, operates on the principle of electromagnetic force compensation. Simply put, a weight on one side is to be balanced by electrical force on the other. This electrical force is inextricably linked with the Planck's constant and can be directly referred to the new kilogram definition. As this balance is the first self-calibrating instrument of its kind, masses determined as reference or standard masses for calibrating scales and balances are no longer required. Another advantage of the Planck balance is its wide measuring range, from milligrams to one kilogram. At the end of the year, the first prototype of the balance will be available and ready for use.
At last, a balanced article.
(Score: 5, Funny) by driverless on Wednesday June 21 2017, @04:31AM (10 children)
For those who aren't aware of how this works, you put your reference kilo on one and of the Planck and the weight to measure on the other. When the Planck balances, you've reached one kilo.
(Score: -1, Troll) by Anonymous Coward on Wednesday June 21 2017, @04:52AM
Oh we know how it works. Every Soylentil is a drugged out drug addict and a precision scale is essential piece of drug paraphernalia. LEGALIZE IT!!!!!111! Dudebro I'm high as a kike from sniffing nigger sweat.
(Score: 2) by maxwell demon on Wednesday June 21 2017, @05:21AM (7 children)
No, you put the weight to measure on one side, and Planck [wikipedia.org] on the other.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by AthanasiusKircher on Wednesday June 21 2017, @06:15AM (6 children)
And if you don't measure it right, they make you "walk the Planck."
On a more serious note, why is the prototype losing mass but the others aren't? If they're made to be structurally identical, what's the deal here?
(Score: 2) by AthanasiusKircher on Wednesday June 21 2017, @06:20AM (5 children)
Actually, even better question -- how do we know the original is getting lighter rather than the copies getting heavier? IIRC the original has only been taken out a handful of time since the 19th century. How do we know it's the original that changed?
(Score: 1, Interesting) by Anonymous Coward on Wednesday June 21 2017, @06:51AM
The reference kilogram, by definition, can not change mass. You could snip a visible chunk off it, and the mass would remain exactly a kilogram by definition.
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @07:24AM (1 child)
There are 6 copies stored with with ISK, as well as numerous copies around the world.
They are occasionally brought together for a weigh-in.
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @08:25PM
No! They [wikia.com] must never come together!
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @09:28AM (1 child)
Well, if there are 7 objects, of which 6 continue to compare pairwise equal, while the seventh is lighter compared to any of the other six, by the same amount each time, which of the following explanations is more likely?
The unfortunate thing with the kilogram is that the outlier is the reference body.
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @04:24PM
The one outlier has seldom been taken out. The others are used as national references, and are thus more often messed with.
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @09:39AM
Whoever moderated this as informative obviously didn't even understand the summary. This was (hopefully) meant humorously; it in no way describes the actual operating principle of the balance.
(Score: 2) by bob_super on Wednesday June 21 2017, @06:06AM (2 children)
> Researchers Developing a New Balance for the New Kilogram
That really sounds like some new-age yoga + miracle diet pill spam you'd flag without reading.
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @01:28PM (1 child)
And also a trademark violation, "New Balance" is the running shoe brand...
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @05:39PM
At least New Balance is American-made.
(Score: 3, Insightful) by stormwyrm on Wednesday June 21 2017, @06:36AM (6 children)
I can't seem to find any references to the Planck balance except in the many clones of the linked article, which all seem to be based on a press release from Technische Universität Ilmenau, which invented the thing. The fact that the term doesn't seem to be mentioned elsewhere (try Googling "Planck balance" Ilmenau [google.com]) makes me think that any scholarly articles describing its operation might be in German only. If it's seriously being considered as the basis for the SI definition of the kilogram, there ought to be a lot of peer-reviewed papers describing it.
Numquam ponenda est pluralitas sine necessitate.
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @09:36AM (4 children)
If you remove the quotes, then you'll find plenty links to a Watt balance [wikipedia.org] which seems to be the proper name of that balance used to redefine the Kilogram. The authors of the article probably got confused because the new kilogram definition is based on Planck's constant.
(Score: 2) by stormwyrm on Wednesday June 21 2017, @10:06AM (3 children)
Numquam ponenda est pluralitas sine necessitate.
(Score: 2) by opinionated_science on Wednesday June 21 2017, @10:32AM
I would imagine (not RTFA!) the principles are now implemented in solid-state. There has been astonishing advancement in micro-electronic, micro-mechanical and micro-magnetic materials... (look at your computer and phone!).
As a side bar, and before I have my coffee....if this becomes standard the measuring devices might become very cheap - who knows what a really accurate mass-balance could be used for?
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @12:27PM (1 child)
I think the Watt balance has been renamed Planck balance to keep the Germans happy. They have historically supported replacing the kg artifact with a Silicon sphere that has a known number of atoms.
(Score: 2) by stormwyrm on Wednesday June 21 2017, @11:15PM
Numquam ponenda est pluralitas sine necessitate.
(Score: 1, Interesting) by Anonymous Coward on Wednesday June 21 2017, @11:00AM
Briefly, Planck-Waage / Planck-balance is Ilmenaus marketing name for their superconducting Watt- or Kibble-Balance.
The curent measurement is done by Josephson-junction. Thats where the Planck quantum comes in.
(Score: 1, Offtopic) by realDonaldTrump on Wednesday June 21 2017, @09:40AM
The folks at New Balance have been huge supporters of my campaign and I'm a huge supporter of them. Great American manufacturing firm. I honor their fighting spirit and patriotism. I stand with them 100%. I'll do whatever it takes to make this New Kilogram shoe a success.
(Score: 3, Informative) by esperto123 on Wednesday June 21 2017, @11:22AM (4 children)
The kilogram reference weight is not getting lighter because, until the new definition is adopted, it weighs exactly one kilogram by definition.
What is happening is that the sister weights that are used for several countries and institutions as references are brought together from time to time and their weight compared to the reference (calibrated), and it has been noted that the difference in weights are increasing, some more than others (see https://upload.wikimedia.org/wikipedia/commons/thumb/c/c9/Prototype_mass_drifts.jpg/399px-Prototype_mass_drifts.jpg [wikimedia.org]) and this uncertainty, albeit small, is a problem, even worse considering that the kilogram is the only physical reference still tied to a physical object not a absolute parameter, so if you loose or damaged it, we are screwed.
My only question is if it is decided that the watt balance will be the method used to redefine the kilogram, from what I recall there were a few methods competing, including one that uses a sphere made of a single crystal of silicon (of a single isotope) that is polished to an unbelievable level of precision, so you can know the exact (or to a very very very high precision) number of atoms there, and derive from that the atom weight. Derik from youtube channel Veritasium has a couple of very interesting videos about this.
(Score: 2, Disagree) by Thexalon on Wednesday June 21 2017, @01:37PM (1 child)
Except that you can't, due to isotopes: Some forms of hydrogen have extra neutrons, which makes them a lot more massive than the basic 1-proton 1-electron hydrogen, for example. When you're looking for an extremely high level of precision, that's going to matter.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 2) by esperto123 on Thursday June 22 2017, @11:13AM
That's why the crystal is made pretty much of a SINGLE isotope, I guess they cannot say for sure it has only one isotope because they cannot analyze every atom in there, but it is as close as it gets, it's a quite amazing thing.
(Score: 0) by Anonymous Coward on Wednesday June 21 2017, @02:03PM
So if I steal one half of platinum in the Paris kilogram, it would not actually be lighter? Sounds like a perfect crime, which by definition was not committed.
(Score: 2) by esperto123 on Thursday June 22 2017, @04:29PM
For reference, today scientific american posted an article about the silicon sphere https://www.scientificamerican.com/article/sphere-made-to-redefine-kilogram-has-purest-silicon-ever-created/ [scientificamerican.com]
(Score: 2) by Soylentbob on Wednesday June 21 2017, @12:05PM (4 children)
Neither the article nor the summary (which appears to be a complete copy of the article; is there a risk for Soylentnews, copyright-wise?) helped me to understand the Planck balance. Apparently the concept is described as Watt balance [wikipedia.org] on wikipedia (it was used to determine the Planck constant for a given weight-definition, I think).
(Score: 4, Insightful) by deadstick on Wednesday June 21 2017, @12:36PM (3 children)
How would that measure the mass of the sample? It seems to be measuring the weight and inferring the mass, using an assumed value for g.
If I'm reading it correctly, one "new" kilogram would have different masses at the North Pole and the Equator.
(Score: 1, Informative) by Anonymous Coward on Wednesday June 21 2017, @01:38PM (1 child)
By additionally measuring g at the very same place, and dividing the weight by the measured value of g. Note that you don't need to know the value of any mass to do that; the nice thing about movement in the Earth's gravitational field is that the masses of the moving objects all cancel out (well, as long as the mass of the object is small compared to the mass of the Earth, which should be a given for all conceivable experiments).
Correct, so far.
Wrong. There's no reason to assume a value of g when you can measure it.
(Score: 2) by darkfeline on Thursday June 22 2017, @03:30AM
How do you measure g without first having something of known mass (presumably, you would need to know g to measure the precise mass of said object)?
Join the SDF Public Access UNIX System today!
(Score: 2) by Soylentbob on Wednesday June 21 2017, @02:21PM
Not sure. If they don't have any better idea, I'd assume instead of supporting the mass, the currents in the coils could be used to accelerate the mass. (Actually this is the same; supporting it against g means applying a force to it / applying an acceleration in the opposite direction. Once you have a current I1 which works to hold M in place, you add another current I2 and measure the additional acceleration generated by I2. From a2 and I2 you could infer the mass of the object.)
(Score: 0) by Anonymous Coward on Thursday June 22 2017, @02:34PM
...the kilogram is a Planck mass.