Well it's been a long weight, but on balance the results should measure up perfectly.
Weight, what? The perfect kilogram is nearly in Planck's grasp
One of the standards world's toughest nuts, how to redefine the kilogram in terms of universal constants, is close to being resolved – unless a Russian experiment in 2017 throws a spanner in the works. That's exciting for standards boffins, since it means anyone can have an accurate kilogram without having to trek to Paris for …
COMMENTS
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Thursday 15th October 2015 09:01 GMT Mage
Re: Heavy science
We do know the length of a Planck.
Could we thus call the Planck Interval, the thickness?
They do claim: "there is no reason to believe that exactly one unit of Planck time has any special physical significance"
and
"There is currently no proven physical significance of the Planck length; it is, however, a topic of theoretical research. Since the Planck length is so many orders of magnitude smaller than any current instrument could possibly measure, there is no way of examining it directly."
Possibly nothing smaller can be measured, no matter how good instruments get, unless someone invents an Heisenberg Compensator.
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Thursday 15th October 2015 11:21 GMT Anonymous Coward
Re: Heavy science
"At least it will be a weight off everyone's mind when they have finished"
Lucky my old physics teacher is unlikely to be reading this ... as otherwise he'd be shouting "Unit! Unit! You nit!" at you while probably dispatching a well aimed piece of chalk in your direction. The kilogram measures mass and not weight!
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Thursday 15th October 2015 14:19 GMT Anonymous Coward
Re: Heavy science
"Lucky my old physics teacher is unlikely to be reading this ... as otherwise he'd be shouting "Unit! Unit! You nit!" at you while probably dispatching a well aimed piece of chalk in your direction. The kilogram measures mass and not weight!"
...yet is presently defined by a weight.
I fancy your old master would thoroughly approve of OP and his chalk would be flying towards gay Paris.
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Thursday 15th October 2015 14:52 GMT Patrick Moody
Re: Heavy science
The kilogram(kg) is not a measure of weight. The Newton(N) is.
"...yet is presently defined by a weight."
The weight (object) you refer to has a mass of exactly one kilogram, since it is the reference for that. It will still have that same mass, wherever it happens to be.
On Earth's surface, the weight (force of gravity) of a weight (object) with a mass of 1kg will be approximately 9.81N give-or-take depending where and when you measure it.
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Thursday 15th October 2015 07:36 GMT Anonymous Coward
Sorry, but Russia is going to define kilogram in reference to Putin mass
Rumors says that the Russian Academy of Science will soon be asked to redefine all standards in terms of Putin dimensions. Thereby the meter will shrink to ensure Putin is 4.5 metres tall, while the kilogram will be larger to ensure he's light as a butterfly. Time will also be redefines so he's still in his twenties.
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Thursday 15th October 2015 10:51 GMT PNGuinn
Re: What does this mean for the "Olympic Swimming Pool/Double Decker bus" standards?
"As the pool is filled with essentially water it could be defined in moles"
As opposed to non essentially water??
Why moles? are they aquatic?
How about kippers??
And BACON.
Thanks - the one with a map of Friday in the pocket.
NURSE!
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Thursday 15th October 2015 13:32 GMT CrazyOldCatMan
Re: What does this mean for the "Olympic Swimming Pool/Double Decker bus" standards?
> moles ARE aquatic, my wife has fished two out of the swimming pool! I was amazed,
> but they CAN swim.
The ones I generally see can't. Probably because they are missing major body parts (like the body) with delicate cat-gnasher marks on the remains..
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This post has been deleted by its author
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Thursday 15th October 2015 15:26 GMT ratfox
Re: Kelvin?
The unit of a kelvin is based on a degree centigrade which is based on the melting point of a couple of metals (don't remember which) because ice/water/steam is a bit too variable.
Sorry, that's incorrect. The Kelvin is defined as being 0 at absolute zero, and 273.16 at the triple point of water. That's the current official definition, which they are planning to change:
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Thursday 15th October 2015 20:11 GMT Ken Hagan
Re: Kelvin?
"That's the current official definition, which they are planning to change:"
To judge from the link, they are at roughly the point that they were with kilograms a few decades ago. They've decided what they'd like the definition to be, but don't know how to reproduce it with the required accuracy. You'll excuse me if I don't hold my breath.
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Tuesday 20th October 2015 07:50 GMT ratfox
Re: Kelvin?
Wasn't Celsius originally based on 0C being the boiling point of water and 100C being the freezing point.
1) No, that's the reverse.
2) The boiling temperature and to a lesser extent the freezing temperature of water depend on the pressure, so that was a little bit imprecise. Celsius are now defined by the triple point of water, which determines both a precise pressure and temperature. The definition is now roughly: "absolute zero is 273.15 °C = 0 K, and at the pressure of the triple point of water, the temperature of the triple point of water is 0.01 °C = 273.16 K". The 0.01 value was chosen because that was the approximate value under the previous definition, and they didn't want to change all existing thermometers.
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Thursday 15th October 2015 12:22 GMT theOtherJT
Wouldn't it be easier...
To just go back to defining it in terms of water/temperature/volume - seeing as we already have nice clean definitions for temperature and volume? I mean, that's the nice thing about the metric system. The units relate to one another.
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Thursday 15th October 2015 12:53 GMT A K Stiles
Re: Wouldn't it be easier...
Nice theory, and I did like the linky, but is the water in solid, liquid or gas phase? Which you can't tell unless you define the pressure on the water , which leads you to a density calculation, which leads back to mass units? (haven't done the full thinking so I'm sure someone will be along to correct me shortly. Icon 'cos at least he's doing some thinking)
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Thursday 15th October 2015 12:53 GMT John Savard
Too Bad About the Litre
If it weren't for the fact that the litre used to be 1.000028 cubic decimetres - that has since been redefined to be exactly 1 - the gram could be defined as the mass of one cubic centimetre of water. Which was its original definition back when the metric system was first invented. Of course, the trouble with that is that water dissolves nearly everything, at least to a small extent, and so maintaining pure water is difficult.
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Thursday 15th October 2015 14:57 GMT David 132
Not overheard..
Phrases you won't be hearing at NIST/the International Avogadro Coordination project/NPL/NRC:
"Close enough"
"Just a smidge more"
"Eh, it'll do"
"Give it to the work experience kid* to finish off"
"Let's take the average and call it good"
(* but I bet the work experience kid got sent off for "a long weight")
My own take? Just define it as 2.2lb and the job's a good'un.
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Thursday 15th October 2015 15:56 GMT Anonymous Coward
Re: Balls
They wanted to test your reading comprehension and ability to connect pieces of information.
In the article there's a paragraph "One technique is to count the atoms in a sphere of material (Australia's CSIRO has helped contribute to this with its own silicon sphere)."
The picture's label is "CSIRO's silicon sphere".
Since you failed to connect the paragraph to the image, I would call that an E-PIC FAIL.
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