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US Objects To the Kilogram
Velcroman1 writes "For 130 years, the kilogram has weighed precisely one kilogram. Hasn't it? The US government isn't so sure. The precise weight of the kilogram is based on a platinum-iridium cylinder manufactured 130 years ago; it's kept in a vault in France at the International Bureau of Weights and Measures. Forty of the units were manufactured at the time, to standardize the measure of weight. But due to material degradation and the effects of quantum physics, the weight of those blocks has changed over time. That's right, the kilogram no longer weighs 1 kilogram, according to the National Institute of Standards and Technology. And it's time to move to a different standard anyway. A proposed revision would remove the final connection to that physical bit of matter, said Ambler Thompson, a NIST scientist involved in the international effort. 'We get rid of the last artifact.'"
Last I heard, nobody had come up with a way to define mass without referring to an artifact. It seems easy but they all turn out to be circular.
Death to KILLograms!
Ounces and pounds were way a head of the time and are becoming even more useful with the advent of computer systems and the common use of base16.
16 ounces in a Pound is not just coincidence.
F=15 ounces
10 = a pound
We can all agree, I am sure, it's easier to look at 89 and go, 8 pounds 9 ounces. With metric I have to keep moving the decimal place around and remember how many 0s there were in huge words like kilogram, milligram, centigram.
Because this prototypical kilogram is what the definition of the pound is currently based on.
It clearly states this is an international effort, and the objection is not the the unit 'kilogram' but rather to using a decaying (however slowly) object as the reference mass.
seriously, this is pretty old. physicists working in metrology have been working to redefine the kilogram for at least the last few decades
"For I am a Bear of Very Little Brain, and Long Words Bother Me"
The US cares that much why? Its only a trade matter, as we still use primitave imperial measurements. Maybe if we had switched to metric like they had told us we were going to every year in grade school this would be a big deal, but right now, who cares?
Because prices, taxes, tariffs, etc. care about pounds and kilograms. We still have a department of weights and measures, and they still do extremely important work. The fact that you don't ever notice any problems means they're doing their jobs.
We have American pints and British pints; the imperial tone, the short ton, and the tonne; why not have an American kilogram and traditional kilogram as well? That should really simplify things for NASA/EUA coordination.
Funnily enough I never ever think of a kilogram as the weight of some standard weight in a vault somewhere. The only way I ever think about the kilogram is the weight of one liter of water. Also comes in handy when I'm calculating how much liquids I can afford to buy when shopping groceries, given that I often go to the store on foot for the exercise and have to make sure I can manage the haul back.
So, um, does this all really matter? In practice, that is.
.: Max Romantschuk
It's the US of A -- we don't use the kilogram anyway. Change it as you like.
That being said, keep your filthy hands off my hogshead.
Blog,Twitter
"There is one thing of which one can say neither that it is one metre long, nor that it is not one metre long, and that is the standard metre in Paris." - Wittgenstein, Philosophical Investigations
..is about a decimal place in which the instuments available to most of us can't even touch (precicion-wise...) But by all means, carry on.
We're going to let the kilogram "float" and put it on the commodities market. It should triple the value of the gram
For justice, we must go to Don Corleone
I'm not even sure we even use Imperial units anymore...
From reading the news, I believe our units are:
- Hairs
- Stories
- Football Fields
- Libraries of Congress
The US was one of the original signatories to the treaty that defined the meter and started the BIPM which lead to the SI.
All US weights and measures, no matter what standard they are on, come from the National Bureau of Standards which standardized on the metric system, as has the USGS (since the early 19th century).
THe NBS has standard meter and kilograms that are copies of the originals kept in Paris, so the US has a valid reason to wonder about the new kilogram definition.
Newton is a weight. The summary (and the Fox article) are incorrect, while the NIST article correctly refers to the reference mass.
MJC
and misses the point. The variability of the kilogram standard is a scientific and engineering concern, not a political one.
Wikipedia discusses the issue: http://en.wikipedia.org/wiki/Kilogram#Proposed_future_definitions
In a nutshell - in order to create 1 kilogram physical standard masses, you have to first know what a kilogram IS. The physical standards referred to in the article do not appear to have retained constant mass over time. You can't define a constant based on something that is variable, so the current masses are (as I understand it) acknowledged to be an inadequate basis for the definition of the unit. The problem arises when you try to pick something to define it with that is both stable (i.e. a fundamental property of the natural laws of the universe) and practical (can actually create one to use as a practical mass standard against which you can prepare working standards.)
From articles that have popped up about this over the years, my guess is they will have to pick something as a basis and then work on various practical techniques to get as close to that ideal as possible - the question is what specifically to pick. N Carbon atoms? N Si atoms? What are the pros and cons when trying to physically create something that represents those numbers? How stable will a standard created according to a chosen standard be over time? (I.e., how often to we have to make new master standards? It's an important question - obviously the existing masses were not chosen with the expectation that their mass would vary with time, so how do we know to trust a given solution?)
So it's not the US objecting to the kilogram as a unit, but rather concern over the methods used to DEFINE the unit. That's something quite rational, not specific to the USA, and of scientific interest. Editors, how about changing the title to "US to Propose New Method of Defining a Standard Kilogram" instead?
"I object to doing things that computers can do." -- Olin Shivers, lispers.org
How does "America" define the pound...?
No sig today...
> ...we still insist on using the pound over the kilogram.
But we don't. The metric system has been legal for trade in the USA since 1866 and the official customary units have been based on it for almost as long. In 1975 it was official adopted by the Federal government for its use and in 1985 it was identified as the "preferred" system for trade. Most goods are labeled in both metric and customary units. It's just that, unlike other countries, the USA has not outlawed the use of customary units as we tend to prefer freedom of choice.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Ugh. I teach college intro physics, and even *I* think that's a sociopathically pedantic distinction.
In my class, I'm happy to use "an object weighs 5 kilograms" to describe the mass of something. I'm just careful to call the gravitational force on the object the "gravitational force", and never the "weight".
It's all clear and consistent unless you try to use the Imperial system, in which the pound is a unit of force. So I don't.
Second, I don't care what the experts say, a kilogram is equal to the mass of one litre of water, which is equal to 1000 cubic centimetres of water, or a 10cm x 10cm x 10cm box full of water.
Does it have to be pure water, or can it have some impurities in it? What temperature is the water? What pressure? When you're trying to do especially delicate measurements, these details matter!
The "weight of a liter of water" will continue to be the useful informal definition, but we need something more precise for technical use.
I don't think so. One of the goals of the metric system over the past century has been to find ways to define the units in terms of fundamental physical constants, as opposed to something completely arbitrary like creating a block of some material and saying "this block is a kilogram". The definitions, by nature are still going to be somewhat arbitrary, but at least once you make the arbitrary definition based on a physical constant, it's easy to reproduce. We could explain to an alien 1/2 way across the galaxy what a second or a kilogram, or a meter is, by telling them a second is "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom."
As long as they are technologically advanced enough to understand that, and to precisely figure out how long that takes, they'll know what a second is. If they aren't advanced enough to deal with that, we can tell them "It's about the amount of time it takes to say 'one-one-thousand'."
More importantly, throughout history, once we have a reasonable definition based upon a fundamental physical constant, we don't have to worry about the units changing value.
Obviously, to most people, having such a level of precision for what a unit is, is not necessary, but for scientists and engineers, in some cases it is very necessary.
H2O is known to weigh 1000 g/L at 4oC with the current metric system. So if we define 1 kg = 1L of water at 4oC at 1 atm, or 55.50843 mols of water, anybody anywhere in the world can have the precise and accurate standardization for kg.
Some were yelling one thing, some another. Most of them had no idea what was going on or why they were there. Acts19:32
"US Objects To the Kilogram"
Who knew ? Also the meter, the Celsius and the liter.
Oddly enough, back in about 1780, the US was desperate to switch to the new metric standard that was being developed by France.
The reason why the US didn't go for it was the definition of the metre. Benjamin Franklin, who was a pretty good scientist when he wasn't being distracted by all this political nonsense, was unhappy with the French definition, which was a certain ratio of the Earth's circumference. The trouble with this is that not only is it practically unmeasurable, but it's not even a knowable value, as it changes depending on what you consider to be the Earth's surface. Franklin was aware that industry can always use as much precision as it can get. Events bore him out as the first metre artifact made turned out to be out by 0.2mm.
Instead he advocated an alternate definition based on the swing of a pendulum of a fixed period. This was a knowable value; it could be theoretically calculated to as much precision as your definition of the second. As the second was at the time was based on the length of the average solar day it could be determined as precisely as you could build your telescopes, it was a much more useful definition.
Unfortunately for complicated political reasons France was unwilling to go with this (possibly because their arch enemies, the British, were also considering a pendulum-based definition), so Franklin decided to stay with home-grown units rather than adopting the new metric system.
So if Franklin had been just a little bit more convincing when addressing the committees in Paris, the US might have been one of the driving forces of metricisation, and maybe my web browser would have the word 'metre' in its spellchecker dictionary.
ha ha space cadet
they are the same thing
silly human
Here's one that scans better:
ha ha space cadet
they are the same frelling thing
you silly human
If Americans want to redefine the kilogram it most likely means that in the next step they try to get royalties whenever someone weighs something.