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.'"

Comments

Get rid of the artifact?

[XanC]

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.

Re:Get rid of the artifact?

[FooAtWFU]

Well, you can try counting atoms. But apparently that turns out to be a royal pain.

Re:Get rid of the artifact?

[Anonymous Coward]

You have to have *some* artifact, but it doesn't necessarily have to be a mass of something. You can use time to define everything if you like. Basically, find some artifact that won't change and define the others from it.

Re:Get rid of the artifact?

[jdgeorge]

Aren't they just proposing removing the dependence on the 1 kilogram cylinders?

From the article:

Physicists may scoff at the thought people allowed to walk among the living who don't know what a Planck value is. But all you need to know is, they're using it to determine the mass of one mole of silicon atoms.

From there on, they'll theoretically be able to deduce a perfect kilogram and it won't have anything to do with lumps of metal ever again. /quote

Re:Get rid of the artifact?

[Guspaz]

The gram was originally defined in relation to a cubic centimetre of water (the temperature originally being 0 degrees, later 4 degrees). Then the IPK was made based on this.

So, what's the problem here? Don't we have a fixed reference, the weight of a given volume of water at a given temperature? Why can't we re-calibrate from that?

Re:Get rid of the artifact?

[Anonymous Coward]

Nah, it's actually pretty easy. You say something like "one kilogram is the mass equivalent of the energy of 3.40812408 gazillion photons with a wavelength of 550.9466543 nanometers." The meter is already defined in terms of speed of light and the second, and the second is defined in terms of the natural frequency of the caesium-133 atom. So in the end, everything is defined in terms of the speed of light and the caesium atom, with no artifacts needed.

Re:Get rid of the artifact?

[Zerth]

Um, the electron-volt(eV)?

I suppose you could use a reference electron, but any old electron will do.

Re:Get rid of the artifact?

[characterZer0]

Last I heard, nobody had come up with a way to define mass without referring to an artifact.

There are several ways to define a KG using constants or atomic weights. http://en.wikipedia.org/wiki/Kilogram#Proposed_future_definitions

The trick is that you not only have to be able to define it, but measure it reliably and accurately.

Re:Get rid of the artifact?

[XanC]

No, because the volume depends on pressure. Which has a mass component. Circular.

Re:Get rid of the artifact?

[Anonymous Coward]

Wouldn't the mass of the water change based on the mineral or contaminate content of the water? Would we have to specify steam distilled water?

Re:Get rid of the artifact?

[Sir_Sri]

You could use an integer number of some base element (hydrogen, helium, carbon 12 something like that). Sort of like time based on radiation emissions or the like. The problem is both precisely and accurately measuring it, and agreeing on what base element. The actual details are fairly simple, you probably want something with the minimum of unstable isotopes that occur in the minimum quantities possible. It's a matter then of finding something suitable (that you can either separate out the isotope easily, or that is naturally acceptable).

Sort of by definition what you said is that no one has come up with a way of doing the above, so they stick with the official masses. There's nothing circular about basing it on some fixed elemental composition. One could even define based on a fixed number of moles of platinum/iridium isotopes to make the current masses 'official'. The issue is whether or not it can be reconstructed exactly from only the definition, which presently it cannot, and under some other system it should be. Yes, the original definition is always going to be arbitrary, that's equally true of time. There's no fundamentally natural reason why our base unit of time needs to have the length of a second, or why we should use the kilogram specifically. There are conveniences associated with it, but it's not like there's some perfect 1 second pulse from the sun or perfect gram that is naturally occurring.

Re:Get rid of the artifact?

[Anonymous Coward]

Last I heard, nobody had come up with a way to define mass without referring to an artifact

E=mc^2

Re:Get rid of the artifact?

[Anonymous Coward]

Every other unit was defined by our understanding of the fundamental forces involved. Basically, time is defined by the speed of light (ie. electromagnetic force), therefore speed of light is constant, by definition. There is no insight into the phenomenon of "mass", therefore it remains an artifact. How else do you define it? 1/12 of the Avagadro's number of C12 atoms in their ground state? Sorry, but we do not "easily" deal with these numbers. And defining Avagadro's number is like defining PI, at least at our current understanding of mass.

http://en.wikipedia.org/wiki/Avogadro%27s_number

So, understand the nature of mass first, then define a unit based on that understanding. Not the other way around.

Re:Get rid of the artifact?

[blair1q]

The artifact system is not reliable and accurate, and certainly not easy to use. If you can't replicate the conditions of the definition in a remote lab, then the definition is bollocks. I mean, what if we lose these things?

The right way to do this is to reverse the definition of Avogadro's number. Instead of "Avogadro's number is the number of C-12 atoms in 12 grams of C-12," you say "Avogadro's number is exactly 6.022141500000000000000000x10^24 and that number of C-12 atoms is 12 grams."

Now anyone who can refine carbon and count its atoms can produce a 12-gram sample. Case closed.

Re:Get rid of the artifact?

[goodmanj]

The goal is to use a single atom as the artifact. Atoms (of a specific isotope) are always *exactly* the same, so there's no concern about variations in the weight of the artifact over time.

So all you've got to do is build an object with a mass as close to 1 kilogram as possible, precisely count the number of atoms it contains, and then make a definition like:

"A Kilogram is defined as the mass of 5.018451 x 10^22 atoms of Carbon 12".

The difficulty is precisely counting the number of atoms in a macroscopic object: the Avogadro Project has been working on this for years.

This is similar to how a second is defined, as "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."

Re:Get rid of the artifact?

[LWATCDR]

Here I have the soluition. 1 gram = the mass of 6.02x10^12 carbon=12 atoms /12 not weight since that can very with location and atmospheric conditions.

Re:Get rid of the artifact?

[MartinSchou]

But all you need to know is, they're using it to determine the mass of one mole of silicon atoms.

From there on, they'll theoretically be able to deduce a perfect kilogram and it won't have anything to do with lumps of metal ever again.

Yes ... apart from the fact that silicon IS a metal, and that a large collection of atoms that closely together is rightfully called a "lump".

Essentially they're proposing replacing one lump of metal with another. It may not be a cylinder, but it's still a lump of metal.

Re:Get rid of the artifact?

[kenj0418]

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.

kilogram: the amount of mass required to deflect a proton by X degrees at a distance of Y meters.

I'm guessing X and/or Y would have to be quite small.

Re:Get rid of the artifact?

[inerlogic]

check again... *any* matter can be compressed given sufficient force

Re:Get rid of the artifact?

[phyrexianshaw.ca]

that has nothing to do with the argument: all materials, water included, expand when heated, so the density of 1cm^3 of water is a product of the temperature.

the weight of 1cc of water depends on the temperature.

Re:Get rid of the artifact?

[bdcrazy]

I just love ideal physics land. Unfortunately the real world doesn't work that way.

Re:Get rid of the artifact?

[phyrexianshaw.ca]

you want to patent a method to count exactly "3.40812408 gazillion photons" reliably and accurately?

if so, I'm sure the NIST may have an opening for you.

Re:Get rid of the artifact?

[Abcd1234]

No, the new "lump of metal" will be a physical representation of the underlying definition, that being that a kg = the weight of X silicon atoms. No such precise definition exists for the current standard.

Re:Get rid of the artifact?

[Anonymous Coward]

You do realize it's not a real lump of silicon? They are proposing using how much a mole of silicon would weigh, and using that to calculate what a kilogram should be. As an example, they might determine that 1.3423452 moles of silicon = 1 kilogram.

Re:Get rid of the artifact?

[jonbryce]

Do you know anyone who can count individual carbon atoms?

Re:Get rid of the artifact?

[Anonymous Coward]

the volume (density) of liquid water has a very very low dependence on pressure.

Re:Get rid of the artifact?

[tibit]

Ain't no such thing, or else something as basic as an electronic weigh scale wouldn't work. To rephrase: solid metals are compressible enough to measure the effect (strain) due to very reasonable external loads -- you'd think that liquids would be, too. And yes, they are.

Bulk modulus of steel, commonly strain gaged in weigh scales: ~160 GPa
Bulk modulus of water: ~2.2 GPa.
Water is on the order of 100 times more compressible than steel. Yet steel's and similar metals' compressibility (modulus) is routinely used in measurement applications!

Now to give you an idea of how compressible metals are: a soft iron sphere with a single strain gage bonded to it will give you, IIRC, 1m depth resolution if you hook it up to reasonable digital strain meter. I did the math once on Yahoo Answers somewhere, don't have the link handy.

Don't believe all they tell you in grade school for a lot of it is bullshit.

Re:Get rid of the artifact?

[harrkev]

No. The reference electrons are specially-calibrated in the lab to meet the exacting standards of the measurements industry. If you start using sub-standard electrons, you get sub-standard measurements.

I have personally seen the effects of creating matter using electrons with a charge of -0.93 instead of the usual -1. The matter that we were shipping had a net positive charge, so we had to include EXTRA electrons in the order so that the USP guy what not fatally electrocuted when he picked up the box. Do you have any idea how much those extra electrons cost my company?

Please do not even get me started about cut-rate protons. What happens when heavy water is not quite so heavy? You don't even want to know.

Re:Get rid of the artifact?

[Anonymous Coward]

No because gravity is not constant at every point on the planet. Weight <> mass.

Re:Get rid of the artifact?

[Sique]

And it depends on their respective type of forming a solid object how much they actually weigh. A crystal of n atoms is a little lighter than n atoms of the same isotope as a fluid or a gas.

Re:Get rid of the artifact?

[blueg3]

There are fundamental physical constants you can use to define a unit of mass.

Re:Get rid of the artifact?

[Sique]

But you know that it depends on the actual structure of the silicon crystal how much X silicon atoms weigh?

Re:Get rid of the artifact?

[lxs]

There is no such thing as an incompressible fluid in nature. It's one of those abstractions that make calculations easier. At the precision required for this work the compression of water could be a factor. Besides working with a liquid is a PITA compared to working with a solid. (evaporation, need of a vessel etc. etc. )

Re:Get rid of the artifact?

[rgmoore]

No, silicon is not a metal, unless you're using the astronomers' definition of metal (i.e. anything heavier than helium). Chemists generally categorize silicon as a semi-metal or metaloid.

Re:Get rid of the artifact?

[igaborf]

Aren't they just proposing removing the dependence on the 1 kilogram cylinders?

Yes, but what fun would it be to make that the headline?

Re:Get rid of the artifact?

[Abcd1234]

But you know that it depends on the actual structure of the silicon crystal how much X silicon atoms weigh?

No, I don't know that at all. Please to explain.

Re:Get rid of the artifact?

[Anonymous Coward]

And it depends on their respective type of forming a solid object how much they actually weigh. A crystal of n atoms is a little lighter than n atoms of the same isotope as a fluid or a gas.

Well, then it's a good thing that the kilogram is not a measure of weight.

Re:Get rid of the artifact?

[blair1q]

yup:

http://www.google.com/search?q=scanning+tunnelling+microscope

probably a way to speed things up using this, which is one atom thick:

http://www.google.com/search?q=graphene

Re:Get rid of the artifact?

[darkmeridian]

The entire point of redefining the kilogram would be to allow any sufficiently-technical laboratory to make their own mass. Right now, there are forty artifacts that must be kept safe. If you do not have one of these artifacts, you in fact have no way to determine what your kilogram actually is. Hell, the artifacts probably do not even have the same mass as each other. So they are proposing to replace a few sets of metal with an instruction manual on how anyone with the right technology can make their own reference weight. That's a huge difference.

Re:Get rid of the artifact?

[zill]

No one is claiming the new method is perfect or free from artifacts. NIST is claiming it's sufficiently better than "a piece of metal in France" to warrant the change in definition.

Re:Get rid of the artifact?

[ultranova]

No, because the volume depends on pressure. Which has a mass component. Circular.

Unless you measure in zero pressure, at which point the mass component becomes zero, regardless of the size of a kilogram. Squared :).

Re:Get rid of the artifact?

[rgmoore]

Not necessarily. You can define the pressure in terms of the triple point, which is an absolute pressure that depends only on the physical properties of water. The definition of temperature already uses the triple point of water as its fixed point, so you could define mass in terms of a fixed volume of liquid water at its triple point.

A more insidious problem is that the isotopic composition of water isn't fixed and has an impact on its physical properties, including both the density and triple point. This is a potential problem with defining mass in terms of silicon, too; it has three stable isotopes. You can theoretically define it in terms of only one isotope or a fixed ratio of isotopes, but then you have the practical problem of isotopic purity.

I'd think it would be better to define things in terms of an element that has only one stable isotope. Gold would be the obvious choice, since it's also incredibly inert and would avoid problems with the mass changing because of chemical reactions.

Re:Get rid of the artifact?

[zill]

Your solution is basically the same as NIST's proposal, except they use silicon instead of carbon. Silicon crystal are also cheaper than carbon crystals.

Re:Get rid of the artifact?

[berashith]

easy, it is how many weight exactly one kilogram

Re:Get rid of the artifact?

[savvysteve]

Well, you can try counting atoms. But apparently that turns out to be a royal pain.

It is really hard on the eyes... unlike say my wife

Re:Get rid of the artifact?

[chihowa]

But you know that it depends on the actual structure of the silicon crystal how much X silicon atoms weigh?

No it doesn't. The structure of the crystal will only determine its volume.

Re:Get rid of the artifact?

[zill]

Energy is defined in terms of mass so it would become circular.

Re:Get rid of the artifact?

[FiloEleven]

Anyone who knows how to count!

Re:Get rid of the artifact?

[Tumbleweed]

Well, you can try counting atoms. But apparently that turns out to be a royal pain.

Or at least an Imperial pain. :)

Re:Get rid of the artifact?

[multi io]

http://en.wikipedia.org/wiki/Binding_energy#Mass_deficit

Re:Get rid of the artifact?

[Tumbleweed]

Do you know anyone who can count individual carbon atoms?

Well, *I* can, but since *you* apparently can't, you can't *prove* I can't.

Re:Get rid of the artifact?

[JustOK]

+ ...

Re:Get rid of the artifact?

[Nadaka]

No.. she is hard on something else entirely.

Re:Get rid of the artifact?

[ultranova]

I just love ideal physics land. Unfortunately the real world doesn't work that way.

Actually, it does. You do know that's what physics is all about, right?

Re:Get rid of the artifact?

[goodmanj]

Well, you *do* need to create a real lump of silicon in order to ensure that your newly-defined kilogram has the same mass as the old standard kilogram.

But the advantage of the new definition is, in the future anyone who wants to create a kilogram can read your recipe in a book and make their own -- they don't need to use your lump of matter to do it.

Re:Get rid of the artifact?

[jcwayne]

While today's technology may not allow us to get a perfect count, the margin of error would likely be smaller than the margin of error in comparing the masses of two of the artifacts.

Re:Get rid of the artifact?

[Anonymous Coward]

There is a way. Using the Josephson effect and the Integer Quantum Hall Effect.

Science. It works, B...

Re:Get rid of the artifact?

[Anonymous Coward]

Oh, so that's why Monster cables are so expensive - they use only they highest quality electrons in their cables!

Re:Get rid of the artifact?

[KDR_11k]

Low is not low enough. We're talking about something that needs to be accurate down to the microgram level.

Re:Get rid of the artifact?

[Abcd1234]

Ahhh, thank you, very interesting!

That said, all that means is that the reference mass will have a very slight divergence from the theoretical definition. That doesn't change the fact that the kilogram will *have* such a definition, which it currently doesn't.

Re:Get rid of the artifact?

[Anonymous Coward]

That is trivially easy. You make a bar of platinum with the mass you want, more or less, and call it a kilogram. The bar doesn't have a "measurable" mass. It defines the measure.

Re:Get rid of the artifact?

[wagnerrp]

Are you saying that 5000 carat diamond would be a bit expensive?

Re:Get rid of the artifact?

[KingFrog]

Ah, I'm immediately suspicious of any summary that mentions something weighing a kilo, anyway. It's mass, not weight! It's like saying someone masses two hundred pounds...that's weight, not mass! They mass in slugs, which is just amusing as all getout. Metric loses so much of the color the Imperial system has...where else can you measure things in gills, hogsheads, rods, chains, and slugs, anyway?

Re:Get rid of the artifact?

[arouse]

Right, you haven't heard.

So here are natural units

Planck units do not use any prototypes at all, not even elementary particles, but instead rely exclusively on fundamental constants. There are also several other similar systems, all of them non-circular, some are even in use.

Re:Get rid of the artifact?

[nacturation]

And it depends on their respective type of forming a solid object how much they actually weigh. A crystal of n atoms is a little lighter than n atoms of the same isotope as a fluid or a gas.

Lighter or has less mass? Fluid lead pretty much weighs nothing when it's in orbit.

Re:Get rid of the artifact?

[EsbenMoseHansen]

I'd think gold would be impractically soft. You want something stiff, so that you can form a near-perfect sphere of the stuff, and measure the diameter.

Re:Get rid of the artifact?

[u19925]

The problem is not in defining without using any artifact, but defining in a way it can be replicated. I can define 1 gram as a mass of my "SD card", but that want help replicate the unit without having access to my SD card. Length and time can be defined without any artifacts in a way it can be replicated. At this point we cannot define mass without an artifact which can be replicated and the reason for it is that we must come up with a definition which ties with the existing definition. So we can say that 100 billion trillion atom of C12 is 2 gram. This is a perfectly replicable definition. Problem is that it does not tie accurately to the current artifact based definition. The effort which is going on for decades is to conduct experiment to come out with a definition which ties with current 1 kg definition which can be replicated without using any artifacts. One proposal is to use a pure silicon crystal sphere of a known radius and declare (after comparing with the current kg) it as of some fixed mass. This can then be replicated anywhere without having access to original sphere or a copy of it.

Re:Get rid of the artifact?

[dwinks616]

That is incorrect. All chemical reactions result in a change in mass, it's drastically smaller than the change in mass from nuclear reactions, but it's still a change. The structure of crystals indeed affects the mass of the crystal due to binding energy and mass deficit.

Re:Get rid of the artifact?

[m2shariy]

No, because the volume depends on pressure. Which has a mass component. Circular.

Unless you measure in zero pressure, at which point the mass component becomes zero, regardless of the size of a kilogram. Squared :).

And at zero pressure water evaporates like crazy, so either pressure becomes non-zero or you run out of water.

Re:Get rid of the artifact?

[ThePromenader]

Ok, you make the 'kilogram' bar of platinum, and I'll be by to pick it up in an hour. Better still, make a few.

Re:Get rid of the artifact?

[Marillion]

Exactly, A kilogram is a unit of mass, not weight. A kilogram has the same mass whether on Earth, the Moon or floating weightless in space.

Re:Get rid of the artifact?

[BlitzTech]

You have it backwards. The liter was originally defined as 1 kilogram of water at 4C and 760 mm Hg.

A liter is now officially defined as 1 cubic decimeter, which makes the comparison to water only approximate.

Re:Get rid of the artifact?

[Anonymous Coward]

yes, because to reduce the pressure, you take out mass.....

Re:Get rid of the artifact?

[galaad2]

title of this slashdot article should be:

Le Kilogramme is to walk the Planck. :)
http://www.theregister.co.uk/2010/10/28/official_french_kilogramme_marked_for_the_bin/

Re:Get rid of the artifact?

[russotto]

Ah, I'm immediately suspicious of any summary that mentions something weighing a kilo, anyway. It's mass, not weight! It's like saying someone masses two hundred pounds...that's weight, not mass! They mass in slugs, which is just amusing as all getout. Metric loses so much of the color the Imperial system has...where else can you measure things in gills, hogsheads, rods, chains, and slugs, anyway?

This is an amusing fairy tale, but measuring mass in pounds is fairly common, and the term "weight" often actually refers to mass. When you weigh something on a balance scale, it is mass you are determining, not force. Scales which are valid for trade are typically either balance type, or measure force but are calibrated against known masses.

There is a system which measures mass in slugs. There is also a system which measures mass in pounds and force in poundals. And the non-SI kg-f (kilogram force) is commonly used as well.

Re:Get rid of the artifact?

[fermion]

This is essentially what is happening, and it has been going on for a few years.

Essentially a sphere will be created of a specific isotope of silicon and a specific diameter. This sphere will have a known number of atoms. This is superior not only because of degradation of a physical standard, but also because it will be easier to create a standard from basic principles using appropriate lab equipment.

The US is quite late in it's objection as the problem has been known and accepted for many years. TIme and distance is essentially measured with light, and only the kilogram still has a physical representation.

It is probably a simple matter for the US to accept the new standard.

Re:Get rid of the artifact?

[LWATCDR]

diamond is only one form of carbon crystal. Bucky balls can also form crystals.

Re:Get rid of the artifact?

[Goaway]

Has less mass.

Re:Get rid of the artifact?

[Goaway]

When he said "lighter", he was referring to mass, not weight.

Re:Get rid of the artifact?

[ultranova]

kilogram: the amount of mass required to deflect a proton by X degrees at a distance of Y meters.

I'm guessing X and/or Y would have to be quite small.

Care to elaborate a bit? Because I, for one, have no idea what kind of situation are you describing.

Re:Get rid of the artifact?

[Goaway]

I'm going to go out on a limb here and suggest that the people creating the definition are, in fact, aware of this.

Re:Get rid of the artifact?

[Anonymous Coward]

What happens when heavy water is not quite so heavy?

You can always market it as 'Heavy Water Lite.'

Or maybe 'Diet Heavy Water'?

Re:Get rid of the artifact?

[Olivier Galibert]

You missed that one Watt Balance.

The lump of platinum is precise at around 5e-8, the watt balance has reached 3.6e-8 at that point, but they expect to do better than that. The Nist, while holding the record right now, does not seem to have chosen the best path to reach better precisions than that. 1e-9 is expected (hoped? ;-) in some of the french experiments in a handful of years.

    OG.

Re:Get rid of the artifact?

[Goaway]

Well how frickin' accurate do you want to be?

Very, very frickin' accurate. That is the whole point.

Re:Get rid of the artifact?

[Anonymous Coward]

Actually you can do it using the josephson and the integer quantum hall effects.

Science. It works, B.... .

Re:Get rid of the artifact?

[FormOfActionBanana]

Why not silicon? That would be cool.

Re:Get rid of the artifact?

[timeOday]

Actually making one doesn't matter. What matters is that as people find more precise ways to measure mass, they are all converging on the same ideal standard.

Re:Get rid of the artifact?

[selven]

Why not just define one kilogram as 4.531146 trillion trillion cesium atoms? Don't need to bring energy in that way.

Re:Get rid of the artifact?

[Goaway]

If that was the case, we would have switched to using that as a standard.

The only reason we still have a kilogram prototype is that nobody has yet figured out a way to count atom accurately enough to match the accuracy of the prototype.

Re:Get rid of the artifact?

[Low Ranked Craig]

I completely agree with this. Why can't we simply define things as follows: 0 degrees Celsius is the temperature at which pure water freezes @ a specified pressure. From there 1cc of pure water @1 degree celsius = 1 ml = 1 gram. at some point you have to simply pick something arbitrary and stick with it. Why this platinum cylinder and not something more ubiquitous and frankly useful? Water is one of the most common compounds on the planet and arguably the most important one to the life on the planet. Even though it's not completely accurate I use these conversion all the time. If you know the density of a material relative to water you can quickly calculate volume, weight and dimensions knowing only one of the other...

Re:Get rid of the artifact?

[nleaf]

I thought for sure that you were going to segue into a joke about wooden knobs on audio equipment.

Re:Get rid of the artifact?

[Goaway]

The point is that the definition needs to be practical. We need to have a way to actually measure a kilogram using the definition, so we can calibrate our scales. If we can not use the definition to calibrate a scale to some very high accuracy, it is useless.

Re:Get rid of the artifact?

[newcastlejon]

That's a matter of opinion.

It seems to me that physics is about the creation of models of reality and as was once said "all models are wrong, some are useful." Take newtonian gravity, for example.

A physicist might model a solenoid as having zero thickness when calculating one thing or another, but it's obvious that such a thing cannot exist.

Perhaps the difference between mechanics and 'purer' physics is a fuzzily defined one and it all boils down to semantics in the end but the OP was still wrong: water is compressible, just not very much.

Re:Get rid of the artifact?

[DerekLyons]

If counting and weighing photons were so easy... you'd have a point. But it isn't. Pretty much every proposal for replacing the kilogram standard so far has either ended up in a circular definition, or required us to do something we don't actually know how to do.

Re:Get rid of the artifact?

[Anonymous Coward]

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.

kilogram: the amount of mass required to deflect a proton by X degrees at a distance of Y meters.

I think Werner Heisenberg might have something to say about this, since you'd need to know both the speed and location of the proton in order to measure the deflection induced by the mass.

But I'm not actually certain.

Re:Get rid of the artifact?

[anwaya]

And it depends on their respective type of forming a solid object how much they actually weigh. A crystal of n atoms is a little lighter than n atoms of the same isotope as a fluid or a gas.

Lighter or has less mass? Fluid lead pretty much weighs nothing when it's in orbit.

Less mass.

Consider a sample of n particles as a crystal, and a sample of n similar particles as a fluid or gas. The atoms in the crystal have very little motion relative to each other, while the particles in the fluid (or gas) have a lot more motion. More motion means more mass, by a factor of 1/sqrt(1 - v^2 / c^2) times the rest mass (IIRC) for each particle. The sum over the sample for the crystal will be less than the sum over the sample for the fluid (or gas).

Re:Get rid of the artifact?

[queequeg1]

That reminds me the last question my college roommate had on his senior oral exam. He was a physics major and was asked how he would derive Avogadro's number without the aid of certain pieces of modern technology. As I recall, his answer started with something along the lines of the following: "First, I would find a really tiny man . . . "

Re:Get rid of the artifact?

[RedACE7500]

1 gram has always been the mass of 1 cubic centimeter of water at melting temperature, as far as I can remember. 1 kilogram would be 1000 of these. Who needs the artifacts?

Re:Get rid of the artifact?

[Anonymous Coward]

From what I understand a qubic decimeter of water at +4 degrees Celcius weighs exatctly 1 kg.
But perhaps that isn't well defined enough for modern standards.

- Peder

Re:Get rid of the artifact?

[wickedskaman]

Would that mean you are actually entirely composed of atoms of pedantoid?

Re:Get rid of the artifact?

[Mikkeles]

'From there on, they'll theoretically be able to deduce a perfect kilogram ...'

But, in practice, they won't. Plus, they'll have to check their atom count against, guess what?, the cylinder in Paris. I wonder if they have a balance sensitive enough to detect +/- 1 Si atom difference?

Re:Get rid of the artifact?

[Anarchduke]

the wallet?

Re:Get rid of the artifact?

[Mr. Slippery]

You do know that's what physics is all about, right?

Any physics problem that is capable of anything but an approximate solution which relies on either simplifying assumptions or numerical methods, is not about the real world.

"It might be noted here, for the benefit of those interested in exact solutions, that there is an alternative formulation of the many-body problem, i.e., how many bodies are required before we have a problem? G.E. Brown points out that this can be answered by a look at history. In eighteenth-century Newtonian mechanics, the three-body problem was insoluble. With the birth of general relativity around 1910 and quantum electrodynamics in 1930, the two- and one-body problems became insoluble. And within modern quantum field theory, the problem of zero bodies (vacuum) is insoluble. So, if we are out after exact solutions, no bodies at all is already too many!" -- Richard D. Mattuck, A Guide to Feynman Diagrams in the Many-Body Problem

Re:Get rid of the artifact?

[Mikkeles]

No; water contracts when heated up to ~4C, then expands. (Ice is less dense than (liquid) water).

Re:Get rid of the artifact?

[Nadaka]

Close, it is a bulge in my pants.

Re:Get rid of the artifact?

[Anonymous Coward]

sounds like the american capitalist machine wants its filthy hands on international standards too. then again they already have most everythign else in their pocket. i say we boycott their kilogram.

Re:Get rid of the artifact?

[Darth]

The Avogadro project (the thing in your link) has been going on since 2007.

The NIST (the U.S. measurements standards body) provided an implementation of another possible solution to the problem in April of 2007.

To say that the U.S. is just now objecting is inaccurate.

To say that the U.S. is late in its objection ignores the fact that the U.S. has been working on the problem with international standards bodies for many years.

What (unsurprisingly) the Fox News article gets wrong is that the NIST is not submitting a formal objection.
The Consultative Committee for Units (one of the advisory groups for CIPM), of which the NIST is a member, has submitted a formal resolution to change the definition to the CIPM. The CIPM is about to submit that resolution to the CGPM, which is the international body that regulates these definitions.

Re:Get rid of the artifact?

[Nethemas the Great]

I'm not certain what "precisely" he is describing, however I think I get the concept.

Essentially, all mass is understood to have its own gravity. It is known that the gravitational pull from a given mass can bend the path of light. The greater the gravitational force the greater it is bent. Therefore one could assert that a kilogram is a mass sufficient to bend the path of a beam of light by X femtoarchseconds (or whatever fraction of a degree makes sense).

In perfect world that might actually be an ideal way to describe it. However, I am uncertain if our present technology has that kind of precision.

Re:Get rid of the artifact?

[XanC]

Because the volume of water depends on pressure, which has a mass component.

Re:Get rid of the artifact?

[Anonymous Coward]

Ahaha I see what you did there.

Re:Get rid of the artifact?

[Anonymous Coward]

It doesn't not work that way, at least, as far as we can tell...

Re:Get rid of the artifact?

[modmans2ndcoming]

tie the measure of a Kilogram to motion like all the other measures.

1Kg can be defined in term of generated momentum.

Re:Get rid of the artifact?

[modmans2ndcoming]

what does weight have to do with mass?

Structure has of the lattice has no impact on the combined mass the atoms create.

Re:Get rid of the artifact?

[crepe-boy]

The only reason for the discrepancy is that you have been using the wrong kind of cables. You need to use these instead: http://www.amazon.com/Denon-AKDL1-Dedicated-Link-Cable/dp/B000I1X6PM (only $9999.00 each)

Re:Get rid of the artifact?

[ZipK]

Less mass! Less weight! Less mass! Less weight! Hey, hey, calm down you two. New Shimmer is a floor wax and a dessert topping.

Re:Get rid of the artifact?

[modmans2ndcoming]

why would they have to check their atom count against a cylinder in Paris when all they need to do is build their own according to the definition?

Re:Get rid of the artifact?

[modmans2ndcoming]

what high school physics class did you fail?

Weight refers to measure of the force of gravity on a mass. Mass is independent of gravity.

Re:Get rid of the artifact?

[tompaulco]

Now you see why they mentioned circular argument. Is 1 gram defined as 1 cubic centimeter of water, or is 1 cubic centimeter defined as the amount of water that weighs one gram?

Re:Get rid of the artifact?

[Anonymous Coward]

Another Goatse. d9LffL=bad.

Re:Get rid of the artifact?

[kurzweilfreak]

Why would she be hard on a sock? That doesn't make any sense.

Re:Get rid of the artifact?

[Nutria]

Of *course* it's all George Bush's fault!!!

Re:Get rid of the artifact?

[TapeCutter]

"I have personally seen the effects of creating matter using electrons with a charge of -0.93 instead of the usual -1."

Sure skinny electrons increase postage and handling costs but the fat ones are worse since they get stuck in the narrow parts of the wires. This causes all the other electrons to pile up behind them and then my internet connection stops working.

Re:Get rid of the artifact?

[Chris Burke]

Plus, they'll have to check their atom count against, guess what?, the cylinder in Paris. I wonder if they have a balance sensitive enough to detect +/- 1 Si atom difference?

They don't need one. The whole point is that the cylinders are not a reliable or repeatable measure. So they'll get as close a measurement as they can, and it'll have a margin of error that is +/- some number of Si atoms. They'll pick some number of Si atoms in that range, and that will be the new definition of the kilogram and at that point the cylinder doesn't matter any more other than for historical purposes. Plus thanks to the regular structure of crystals you can do a lot better than just weighing them to count the number of atoms. So it will be a more precise measure in the future.

Re:Get rid of the artifact?

[Nutria]

Weight refers to measure of the force of gravity on a mass. Mass is independent of gravity.

Which is fortunate for all those people on the ISS.

For the other 99.9999999999999999% of us of terra firma, "weight == mass" is Good Enough.

Re:Get rid of the artifact?

[Anonymous Coward]

Is this supposed to be a point? You fail, utterly.

The kilogram reference mass is already made, and it is the reference to which all other masses are compared. If you want to buy a kilogram mass, go to a science shop. Note that if you decide to "define" your mass as "the kilogram", you will be using a different unit of measurements than the International System of Units uses.

Re:Get rid of the artifact?

[hudsucker]

Congratulations, you've just recreated the way it was defined from 1795 until 1799, when they switched to using a standard platinum prototype.

Re:Get rid of the artifact?

[Teancum]

The meter was defined as a fraction of the distance along the Prime Meridian from some crazy location in France to the North Pole, and the second was defined as 1/86400th of a day. The problem with these as a system to standardized measurements is that they aren't precise enough. A day can vary by quite a bit and it turns out that even over a fairly long period of time that the Earth still isn't constant. You have precession, slowing of the Earth due to the gravity of the Sun and the Moon tugging at the oceans (giving you tides BTW), variations in the orbit of the Earth, and other factors that make using the Earth as a physical constant for measuring time to be sort of pointless.

Ditto for the meter, as that spot in France that was the original standard for the meter is also moving due to geological forces... by a couple centimeters each year. Eventually it became a "meter bar" but even that isn't quite precise enough and becomes problematic when you try to duplicate the exact distance of a meter for measurements.

On top of these issues is also the isotopic purity of water, where different isotopes of Hydrogen and Oxygen can make a difference. "Heavy Water" really is heavier than ordinary water... the isotopes make a difference. If you say you need to use distilled water, even that has problems, depending on the source of that water and the method of distillation. On top of that, you need to define pressure, temperature, and other features into such a standard that gets really messy. Since pressure is defined in terms of mass, how do you get that standardized again?

You are correct that the rough definition you are quoting was the original definition of a gram at least to define the original concept, assuming "typical" atmospheric pressure on the Earth and that the water is in an open container in a humid environment (so the water doesn't evaporate too quickly before it is measured). The kilogram artifact as mentioned in this article was an attempt to avoid most of the problems associated with a water definition by defining a specific combination of supposedly "stable" metals. The combination of Platinum and Iridium was chosen explicitly because they weren't radioactive, resisted corrosion, and could be easily formed in a laboratory presuming that you had the proper dimensions measured in terms of meters (which were considered fairly accurate for measurement at the time). The problem is that the measurement equipment now currently exceeds the ability for even this fairly stable standard to maintain its mass, and the mass standards are apparently losing mass over time from oxidation and other chemical process simply by existing on the Earth. This happens very slowly, but it is happening, in spite of the fact that most mass standards are kept in double bell jars in a safe at a very secure facility. They are guarded stronger than most monetary reserves and you certainly aren't going to be given one of these standards to be sitting in your bare hand.

Re:Get rid of the artifact?

[Anonymous Coward]

via gravity or charge?

Re:Get rid of the artifact?

[denelson83]

You mean this kind of circular?

Re:Get rid of the artifact?

[Skatche]

You could use a bigger test mass, like a grain of dust. It doesn't even matter how big the test mass is, so long as it's small compared to the kilogram. It'll get deflected precisely the same amount.

Re:Get rid of the artifact?

[Teancum]

The problem has always been trying to decide upon what new standard might be the replacement, not necessarily that it needed to be replaced. There apparently were some objections to the Silicon sphere approach and there were some suggestions to try instead to use an electrical standard (so many watts & volts with a certain applied current that would exert a certain amount of force from which a mass standard could be derived) and some other approaches were considered. I'm not sure how many different ideas were presented, but it was more than a few and the Silicon sphere certainly isn't the only possible solution.

The pound and the inch are defined as a matter of law in the USA in terms of metric units anyway (the inch is 2.54 cm exactly to as many decimal places as you want to make it) so accepting a new standard isn't going to be a problem. The question is if the larger international standards bodies are going to accept any new definition for the kilogram, of which the NIST is a part of those bodies... and which standard will apply.

Re:Get rid of the artifact?

[Teancum]

Not really. Once you have defined the mass in some physical terms, there are other ways which a "standard" can be created. The trick here is to define the mass in such a way that it can be reproduced with nothing more than the raw definition rather than having to do the painstaking task of trying to constantly compare it to the physical standard that exists somewhere.

They aren't really trying to make this new "standard" to be anything but close to the original standard. You shouldn't notice anything in terms of bathroom scales or anything that most people encounter in day to day life, but it will mean that the precision with which things will be measured can be improved with a more refined and updated standard.

There have been several other approaches to defining a mass standard that bypasses the need for a physical lump of anything at all, which is why this hasn't necessarily been the easiest thing to come to a consensus or agreement upon. Also, don't expect this to be the final word on mass either, as the definition of a second has changed even after they got rid of the physical standard of the rotational velocity of the Earth.

Re:Get rid of the artifact?

[MaXintosh]

This.
Before I went into science, I did automation engineering (think factories with robots). A lot of that is fluid power. And any person working with hydraulics worth their salt would tell you that depending on factors, most hydraulic system fluids will compress between .5 and 1 percent per thousand PSI.
So, when I took physics, and they told me that fluids aren't compressible, I objected. The instructor told me that sure, fluids change volume, but only in weird pressures like near vacuums and absurd pressures. To which I pointed out most of the universe is a very low pressure, dotted with spots of exceptionally high pressures. STP ain't standard for anyone but people on the top of the crust of moderate mass rocky planets (and even then, not all of them).

Re:Get rid of the artifact?

[Teancum]

Amen to this post and mod it up! Seriously!

The whole point is that the existing standards aren't accurate enough, and that the measurement devices are now accurate to the degree that measuring the mass loss from one day to the next can be accurately measured and compared to the mass loss in the other 40 official standards that are found around the world.

In other words, the standard isn't standard. That is the point! And it does need to be very frickin' accurate!

Re:Get rid of the artifact?

[Teancum]

You could always freeze the water if you needed a comparison :)

BTW, I agree with your sentiment, I just had to say that though.

Re:Get rid of the artifact?

[Teancum]

Because growing a kilogram sphere of Silicon using 19th Century technology was not possible, you insensitive clod!

BTW, a kilo of pure Silicon does look cool.

Re:Get rid of the artifact?

[thegarbz]

Hell, the artifacts probably do not even have the same mass as each other.

They don't. There's variances between all the official copies which have changed over time: https://secure.wikimedia.org/wikipedia/en/wiki/File:Prototype_mass_drifts.jpg Though technically there is only one official kilogram so even if all the others trend one direction the official answer will be that they are all wrong.

Re:Get rid of the artifact?

[cynyr]

sounds like he wants to use an amount of gravitational force a something causes. Although I thought gravity was also effected by density, see black hole.

Re:Get rid of the artifact?

[SledgeFA]

The 1st thought that came into my mind was basing it on second, meter and ampere. If you are able to apply a precise force via electrical current and are able to avoid friction, you could built a system and measure acceleration or resonance frequency and derive the involved mass from there. Putting it into practise in an experiment that delivers high precision seems to be the difficult part to me.

Re:Get rid of the artifact?

[jschen]

This isn't really my field, but I've given some thought to the use of water for this purpose. The biggest practical problem is the problem of getting the exact same water (in terms of isotope composition) to everybody. You presumably would use Vienna Standard Mean Ocean Water (VSMOW, itself a mix of distilled ocean waters from different locations) as your standard since our temperature definition is already tied to the triple point of VSMOW (defined as 273.16 Kelvin). But the triple point temperature is significantly less sensitive to isotopic composition than the mass is.

Based on the Wikipedia-reported tolerance for the isotopic composition of VSMOW, I calculate that VSMOW is defined with a tolerance for +/- 1 ppm average molecular weight difference. That roughly translates into a +/- 1 ppm difference in density. I doubt anyone at NIST (or at any other group) would find such a large error bar to be acceptable for a new definition of the kilogram. That probably is a major reason why silicon is favored: Thanks to all the research in the semiconductor industry, we're really good at getting pure silicon-28.

Re:Get rid of the artifact?

[phyrexianshaw.ca]

if you go to a science shop and buy a "kilogram mass" what makes you think it will weigh one kilogram?

how do you measure it at home? likely you put it on a scale and trust whatever it tells you. but the scale is calibrated with a degree of error.
even the weight itself is manufactured with a degree of error. even if you take that mass and compare it directly against one of the standard masses, even if your weight WERE a perfect kilogram: it will be off due to the atomic decay of the materials used to make the originals.

we DO need to move away from using mass to define mass. it leads to circular logic arguments all day long!

Re:Get rid of the artifact?

[NFN_NLN]

And it depends on their respective type of forming a solid object how much they actually weigh. A crystal of n atoms is a little lighter than n atoms of the same isotope as a fluid or a gas.

There are some absolute constants in the universe, the speed of light in a vacuum, planks constant, the charge of an electron. These things will NEVER change over time AND can be measured anywhere in the universe without a reference object.

Look into "Natural Units", there have been several attempts to define the basic units: mass, time, length, temperature...

http://en.wikipedia.org/wiki/Natural_units

Re:Get rid of the artifact?

[Anonymous Coward]

gas *is* a fluid.

Re:Get rid of the artifact?

[Rich0]

Yup - the last I read on this the problem was that the artifact was still considered more accurate. Of course, the artifact will only get less accurate over time (very slowly), and the silicon method will only get better.

If the standards bodies hadn't done such a good job creating the artifact and its copies in the first place, it wouldn't be quite so hard to displace them. It turns out that the artifact isn't actually all that bad a standard. If it ever got lost we could switch to the silicon method at any time, though obviously the longer we wait the closer we can get them synchronized.

Re:Get rid of the artifact?

[nacturation]

Consider a sample of n particles as a crystal, and a sample of n similar particles as a fluid or gas. The atoms in the crystal have very little motion relative to each other, while the particles in the fluid (or gas) have a lot more motion. More motion means more mass, by a factor of 1/sqrt(1 - v^2 / c^2) times the rest mass (IIRC) for each particle. The sum over the sample for the crystal will be less than the sum over the sample for the fluid (or gas).

So almost like resting mass + relativistic mass?

Re:Get rid of the artifact?

[Anonymous Coward]

More like a Customary pain.

Re:Get rid of the artifact?

[shutdown -p now]

"A Kilogram is defined as the mass of 5.018451 x 10^22 atoms of Carbon 12".

... at rest.

Re:Get rid of the artifact?

[Anonymous Coward]

How trivial is it to physically verify the 9,192,631,770 periods of radiation that occur within the second?

Re:Get rid of the artifact?

[zippthorne]

1m depth in air, (really, really, impressive...) or 1m depth in water? Or mercury?

Re:Get rid of the artifact?

[zippthorne]

Incompressibility is an assumption that we use in fluids equations to simplify things so we don't need an earth-sized super-computer to calculate the efficiency of shapes of various vessels for traveling through it, or relatively low reynolds number flow rates through networks of tubes.

It's a pretty reasonable approximation, too, for those domains.

But it's not an inviolable law. It's not even "believed to be fundamental" like the laws of thermodynamics. It's just a useful assumption for the purpose of eliminating higher order terms from your equations, to get a broad view of select, but practical, phenomenon.

Re:Get rid of the artifact?

[russotto]

what high school physics class did you fail?

High school physics isn't the be all and end all of physics.

Weight refers to measure of the force of gravity on a mass. Mass is independent of gravity.

Really? So when you are weighed in a doctor's office, what sort of scale do they use? Unless it's a digital one, it's probably a triple-beam balance. Put that thing on the moon, and it'll tell you the same weight as it does on earth. In most common use, "weight" refers to "mass", not force due to gravity. The fact that provided you stick to the surface of the Earth mass and force due to gravity are directly proportional just muddies the issue.

BTW, if weight is the force of gravity on a mass: If you're in low orbit around the earth, how much do you weigh? A balance scale is useless, as is a pressure-sensitive one. The usual answer is that you're "weightless". But the force of gravity in low orbit is nearly the same as it is on the surface; GMm/R^2 doesn't lie. So this is a meaning of weight different from either "mass" or "force of gravity on a mass".

Re:Get rid of the artifact?

[modmans2ndcoming]

no, because a mass measurement is normalized for the force of gravity. the astronaut's mass measurement on earth would read the same on a normalized measuring device on the moon.

Their weight would not be the same though.

Re:Get rid of the artifact?

[modmans2ndcoming]

the only reason it will tell you the same numbers is because of the configuration of the device. you are not 180 lbs on the earth and on the moon. If you are on the earth and weigh 180, then you are 30 lbs on the moon.

the reason the scale reads the same on the moon is because the force of gravity changes uniformly on the masses on the left and right of the fulcrum and the ratio of balance will not change just because the force int eh system changes.

Weight is a measure of force. Nothing more.

No wonder we have problems in the physical sciences.

Re:Get rid of the artifact?

[SomeKDEUser]

The Poisson ratio of water is 0.499975, which is not nearly close enough to 0.5 to be acceptable.

Re:Get rid of the artifact?

[coerciblegerm]

*groan*

Re:Get rid of the artifact?

[PapayaSF]

The difficulty is precisely counting the number of atoms in a macroscopic object

Then why not count the precise number of atoms in a microscopic object and make the International System of Units work for us here? Just define the yoctogram as a certain number of atoms, then multiply it by 10^27 to get a kilogram.

Re:Get rid of the artifact?

[Nutria]

But 99.9999999999999999% are not on the Moon and never will be, since they're on the Earth, where weight effectively equals mass.

Which is why for all practical everyday purposes and uses, 1 kg == 2.205 lbs.

Re:Get rid of the artifact?

[modmans2ndcoming]

but when we are talking SI units, it is a measure of mass and only a measure of mass.

Re:Get rid of the artifact?

[modmans2ndcoming]

and BTW.... if I weigh myself in kilos, I would weigh the same number of kilos no matter where I weighed myself in the universe. It isn't so with pounds, practical or not.

Re:Get rid of the artifact?

[Anonymous Coward]

Yes, the US has certainly been posturing about the issue for a while...

The Australian project is reality, and spheres have been delivered, and it would seem general knowledge that this is considered the new standard.

Personally, I think the US should get with the program, and ditch the imperial system altogether, it would certainly 'give it some weight' in the argument. Hehe.

Re:Get rid of the artifact?

[Dunbal]

The meter has already been defined in terms of the speed of light. The circle stops there.

Re:Get rid of the artifact?

[Sparr0]

In which case I believe he was incorrect. The lower weight is caused by a greater displacement of air. Lower mass has no explanation that I can find.

Re:Get rid of the artifact?

[ThePromenader]

Platinum is running at about $50000 a Kilogram. Someone needs to get a sense of humour.

Re:Get rid of the artifact?

[lonecrow]

I am confused. When I was a kind I am sure I was taught that the basic measure of mass was a gram and that it was defined as 1 cubic centimeter of some sort of purified water at specific temperature.

Was there any truth to that?

Re:Get rid of the artifact?

[Nutria]

No shit, Sherlock.

Let me ask you a question: how many people say "My body's 65kg of mass exerts 637.4N of gravitational force"?

Right. No one says that, except may is Physics class.

Every one says "I weigh 65kg", even though the kg is a unit of mass, and weight is a unit of force.

Re:Get rid of the artifact?

[Anonymous Coward]

Nerds clearly have different priorities. Pedantry > Money + sense of humour.

Note to nerds. Many wives insist on being right, even if they aren't. That's incompatible with some nerd modes of operation.

Re:Get rid of the artifact?

[Anonymous Coward]

can we use a frickin shark with a laser attached as a standard for the kilogram, or maybe 1 million of something. that would make it an international measure of surety.

Re:Get rid of the artifact?

[Anonymous Coward]

Yes, and now you'd have to get a callibrated machine to measure speed or distance and an angle of deflection.

Having a chunk of metal in a room with air conditioner for a hundred years seems to be a lot easier.

Re:Get rid of the artifact?

[Anonymous Coward]

Yes... if you are 200 years old.

Quoting Wikipedia: 'On 7 April 1795, the gram was decreed in France to be equal to “the absolute weight of a volume of water equal to the cube of the hundredth part of the meter, at the temperature of melting ice.”'

The current kilogram prototype originates from 1879, and was standardized in 1889. But even in 1799 the kilogram was defined based on a metal prototype, so...

(and why kilogram instead of gram?

Re:Get rid of the artifact?

[Captain Segfault]

if I weigh myself in kilos

You just used the very colloquial definition of weight that you've been rallying against.

I would weigh the same number of kilos no matter where I weighed myself in the universe. It isn't so with pounds, practical or not.

The units aren't the issue. The number of pounds necessary to accelerate me 32 feet per second^2 does not depend on my being on Earth's surface!

Re:Get rid of the artifact?

[dalleboy]

Must it be easy? Just define the kilogram as the mass of exactly (6.0221415*10^23/0.012) unbound carbon-12 atoms at rest and in their ground state [1] and at zero K, and let the future worry about the rest.

Re:Get rid of the artifact?

[The_mad_linguist]

So you define it relative to the triple point of water.

Re:Get rid of the artifact?

[uninformedLuddite]

The metre was redefined in 1983 it is now the distance traversed in vacuum by light in 1/299792458 of a second (17th CGPM )

Re:Get rid of the artifact?

[Stemp]

Instruction manual : take 1 (one) litre of water, done. :)

Re:Get rid of the artifact?

[SharpFang]

I'm actually overclocking my computer by using electricity made of electrons with 3/4 spin.

Re:Get rid of the artifact?

[Pfhorrest]

Speaking of natural units, there's always the theoretically easy solution of defining our units of mass in terms of distance (which is already defined in terms of time and c): define one kilogram as the mass of a singularity with a Schwarzschild radius of ______. Fill in the blank so that the mass of such a singularity equals the kilogram as currently defined and there you go.

Problem is, practically speaking, nobody wants to have to create a singularity every time they need to check that their kilograms really match the standard.

Re:Get rid of the artifact?

[bh_doc]

Nice idea, but it's circular. Energy is defined in terms of mass (and distance and time). You need Plank's constant to convert from photon frequency to energy, and unless you already have a definition for the mass unit (kg), Plank's constant becomes essentially arbitrary.

Re:Get rid of the artifact?

[goodmanj]

That's essentially what they're doing. The difficulty is that you want to ensure the new mass definition exactly matches the old one. There's no problem in principle with skipping this step, but in practice if you don't you need to throw out every measurement device with a sensitivity greater than the difference in definition.

So to ensure the atomic definition is consistent with the "lump of platinum" one, you need to bridge the gap between the atomic scale and the macroscopic one, which involves counting the number of atoms in a macroscopic object somehow.

Re:Get rid of the artifact?

[Pfhorrest]

Black holes are not more massive because they are dense, they are dense because they are more massive. (More mass means more gravity which squeezes the matter together more densely).

In principle a black hole does not need to be a spectacularly massive object. If our sun was somehow compressed into a black hole, it would not magically grow more massive. We'd continue orbiting it just like usual. The only difference is, things that would normally collide with it and by deflected (like the interplanetary medium) would instead just fall into it and add to its mass, making it constantly grow in mass, unlike our present sun. That is the only sense in which black holes "suck" more than other stars.

Of course, our sun wouldn't become a black hole of its own accord. Only much more massive stars would. So black holes usually are quite massive. But it's not because they are dense. They are black holes because they are dense, but they are dense because they are massive; and the are not massive just because they are black holes.

Re:Get rid of the artifact?

[doshell]

So what do you do when you want to produce a 1kg weight to use in physical experiments? Do you take 3.40812408 gazillion photons with a 550.9455543 nm wavelength and place them on one of the plates of a scale?

It does not suffice that you define the kilogram rigorously. The definition must also suggest a practical way to produce a 1 kg specimen in the lab (up to a given degree of precision), which yours doesn't.

Incidentally, the reason why the silicon sphere thing hasn't yet replaced the International Prototype Kilogram is that it still gives less precision than the IPK, despite all the shortcomings of the latter (or so I read lately).

Re:Get rid of the artifact?

[IndustrialComplex]

The meter has already been defined in terms of the speed of light. The circle stops there.

We hope. We are afterall, assuming that it hasn't or will not change.

Re:Get rid of the artifact?

[Goaway]

Lower mass is because of the energy of chemical bonds. Energy is mass. The difference is miniscule, but exists.

Re:Get rid of the artifact?

[tibit]

In water.

Re:Get rid of the artifact?

[kmoser]

African or European speed of light?

Re:Get rid of the artifact?

[Barryke]

Are you suggesting light migrates?

Re:Get rid of the artifact?

[Anonymous Coward]

you seriously have some problems with your understanding of the force of gravity and weight.

Re:Get rid of the artifact?

[DrVomact]

It is probably a simple matter for the US to accept the new standard.

That's right! Who cares about the rest of the world! Simply define the new kilogram (US) in terms of sticks of butter. Of course, the British will also insist on going their own way, and will define a kilogram as "6 stone, more or less". The French will seek revenge by defining the kilogram in terms of wheels of camenbert. The Germans will rule the world by default, as they will do something sensible.

Re:Get rid of the artifact?

[DrVomact]

and BTW.... if I weigh myself in kilos, I would weigh the same number of kilos no matter where I weighed myself in the universe. It isn't so with pounds, practical or not.

I am not sure I understand what you just said. The first sentence almost sort of makes sense, but then your distinction between pounds and kilos seems to indicate you are completely off.

You would indeed weigh the same on earth as on the moon...if you are using a balance scale. That's because the reference weights would weigh about one sixth of what they do on earth...as would you. However, if you are using a spring scale (i.e., a common "bathroom scale") or any type of scale that relies on pressure to measure weight, the scale would say you weigh one sixth of what you weigh on earth.

I do not understand why you think pounds are earth-bound, while kilos are universal. In any place where there is sufficient gravity (or its equivalent, provided by acceleration) for "weighing" to be a sensible undertaking, it does not matter whether your scale is calibrated in pounds or kilos—the type of scale is what determines whether you get constant results or not.

Re:Get rid of the artifact?

[DrVomact]

All spelling and grammar errors are intentional. Grammar Nazis' need entertainment.

Your use of the apostrophe is incorrect.

Re:Get rid of the artifact?

[Anonymous Coward]

"Essentially a sphere will be created of a specific isotope of silicon and a specific diameter."

Yeah, unfortunately that's what the rest of the world working on this came up with. The sphere as the shape is stupid as f***. They choose a well-defined material used in the semiconductor industry and where purity is clearly needed and discerned (via the process of distilling/purifying and seeding the silicon),...that was smart.

But to then go and use the sphere as the shape, for metrological reasons is just insane. When the F*** did they ever come up with a spherical chip? Oh, wait, right, they haven't.

Given all the research into making things ridiculously flat for the substrate for chipmaking (same industry as making the silicon, and which several years back was thought to be holdup in making small chips), they pick a sphere. All the routines into interferometer work and planing down mirrors, they use a sphere. They can comparatively map it one to one use a liquid mirror, and they choose...a sphere. (Yes, you can map a sphere, but it's easier plane to plane.) Now you've got to map a surface which is machined down instead of planed, and is more susceptible to various wear points during handling (since it's all the same).

The error is just a freaking pain the neck. Versus check for plane on 6 sides, mapping it on 6 sides, and check for right angle based on laser and time of flight testing, makes dimensionally checking a cube with its corners and simple math, they want to map the diameter of an object with it's definitionally infinite number of points on it with no given point truly mappable with a laser function, so it's sheer interferometer checking. What a crock. One or two crappy mappings of a sphere, versus verifiable checks and several ways to check the planes on a cube.

Morons.

"It is probably a simple matter for the US to accept the new standard."

*laugh* That's a good one. I hope we don't. It's a crappy standard. But the NIST are professionals, and they are nice so they'll work with you, even though your standards are shit.

The new kilogram standard is already considered pretty crappy by anyone who's analyzed it. They're probably already working on the next standard, and rapidly too, since the one that the rest of the world came up with, is so cumbersome.

Dude, the US NIST department is top notch I dislike big government, and not because it's popular to say that now.. But to me, it's the one institution in our government that simply rocks, has a clear purpose, executes, and explains their research. Weights and measures prevents fraud, provides fairness in the marketplace, and has clear scientific and industrial uses and underpinnings. Whether time keeping, coming up with frequency combs, or having a nearly readable website explaining their role to the general public, the NIST does real good.

So I really, really doubt they were behind the rest of the world. In fact, cumulative, the rest of the world probably had to group together to do what the NIST probably came up with on their own, and I'd bet that the "US" solution was a better solution critically.

And it has squat to do with the kilogram. That's just what you guys are going to bond it to, for historical reasons. (Sort of how a meter is now defined; has little to do with the actual original definition.) It has more to do with measuring mass in general. You're going to essentially come up with method of measuring mass, and correlating that with your precious kilogram. You might as well as define the pound. The whole point is to get away from the stupid precious French weights and to connect it to time and length of a given material, and I can tell you on the time aspect, the NIST has been at the forefront for years.

The crappy Fox article got one thing right--you guys have been relying on a crappy standard for too long, and we've been too nice in letting it happen.

Re:Get rid of the artifact?

[DigiShaman]

Weighted on Earth. The only Earth in the universe. Bad idea.

Perhaps something more universal, like with a centrifuge where the pull of 1 liter of water at X length from center at Y RPMS. Better yet, we need to our measurement system redefined based on all universal constants.

Re:Get rid of the artifact?

[CarbonShell]

Seriously?
Faux News reporting on ANYTHING that even tangents France and you expect anything useful to come out.

ok,ok, the France part is redundant, though it would just worsen any propaganda.

Re:Get rid of the artifact?

[Muad'Dave]

What's with the apparent fascination with spheres? Wouldn't they be a lot harder to make 'perfect' than a cube, say? I could easily devise 'perfectly' parallel plates down to a wavelength of light, but how would you easily determine that a sphere were perfectly round?

BASE16

[AmigaHeretic]

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.

Re:BASE16

[Yvan256]

Computers use base 2, humans use base 10.

Re:BASE16

[Anonymous Coward]

You could probably sound more retarded, but I'm unsure as to how.

Re:BASE16

[morgan_greywolf]

You're almost right. Base 16 (hexadecimal) happens to be a convenient way for humans to do base 2 math. Any programmer worth his salt can do hex math in his head. ;)

Re:BASE16

[kenboldt]

this ^

Re:BASE16

[gfreeman]

ha ha space cadet
they are the same thing
silly human

Re:BASE16

[bluefoxlucid]

The Chinese Suan Pan had 5 earth beads and 2 heaven on each rod, with each heaven bead being 5. You counted 1, 2, 3, 4, then zero'd the Earth and shifted a Heaven bead for 5; 6, 7, 8, 9, then zero'd and shifted a Heaven bead to make 10; then 11, 12, 13, 14, and then finally used that last Earth bead to make 5 + 10 = 15. Then 1 on the next rod meant 16. This is because there were 16 liang to 1 jin.

Re:BASE16

[Anonymous Coward]

"this ^" ... is the truth? Or an example of how to sound more retarded?

Re:BASE16

[BurningTyger]

Sure. Please do the following calculation in your head (you can use your fingers too)

Let's say a bag of wood weighs 8 pound 9 ounces, and you want to buy 3 bags. What is the total weight in pound and ounces?
Versus, you have 8.9kg of wood, and you want to buy 3 bags, what is the total weight in kg?

I am sure you'd be able to multiply in BASE16 if you are trained for it, and memorize the BASE16 multiplication table when you were a kid. But for the rest of us, BASE10 is what we learned and used to.

Re:BASE16

[man_of_mr_e]

Yes, but 16 is easier to carve up into smaller pieces using fractions.

10 is divisible by itself, 5, 2, and 1.
16 is divisible by itself, 8, 4, 2, and 1

12 is even better than 16
12 is divisble by itself, 6, 4, 3, 2, and 1

.

Re:BASE16

[Anonymous Coward]

CPUs use base 2 and many Computer "Systems" use base 16.

I'm human and I use base 8. Worked in a knife sharpening factory as a kid. :(

Re:BASE16

[Conspiracy_Of_Doves]

All bases are base 10

Re:BASE16

[blair1q]

By posting the same thing anonymously.

Re:BASE16

[kenboldt]

let me expand it for you as you appear to be new to the interwebs and cowardly anonymous.

I agree with this statement above. I do not feel the need to elaborate as the statement to which I am referring summarizes my position on the topic adequately.

Re:BASE16

[phyrexianshaw.ca]

quick, 0xFA0^2 (shouldn't take more than 2 seconds. :P)

Re:BASE16

[Anonymous Coward]

Then you have all these math professors with "Doctorates" going around saying .9999... repeating really = 1

because 1/3 = .333..repeating, so 1/3 + 1/3 + 1/3 =1

Except 1/3 != .333...repeating, we just have no real way to represent it in base10.

You tell these professors by that logic that then almost every fraction in base2 = 1. So 1/5 = 1?

Re:BASE16

[Anonymous Coward]

Double WHOOOSH!!

Re:BASE16

[Mikey48]

"All your bases are belong to us"

Re:BASE16

[Anonymous Coward]

Duh, it's 24 pounds and 27 ounces.

Geesh, how hard can it be?

Re:BASE16

[Anonymous Coward]

Yes, but 16 is easier to carve up into smaller pieces using fractions.

And the point of doing that is...?

Re:BASE16

[schon]

tl;dr

Re:BASE16

[inerlogic]

ok... in my head....
3 8s is 24, 24 pounds,
3 9s is 27, 27 oz,
27 oz is 1lb, 11oz

25lbs 11oz

it took longer to type out than it do to multiply it the first time through....
'course i went to school back in the 80s when they actually taught us how to do math....

i could also do it in hex, octal and binary if you'd like :)

Re:BASE16

[thehostiles]

if we're talking about redefining the metric system, we might as well make gram = metre = litre of water (well, approximately) so we don't have to worry about all this x10^-2 shenanagains

Re:BASE16

[idontgno]

Alas, I can't find anyone around here who sells wood in bags. Metric or otherwise.

I can get it by the cord, by the board foot, or the stick.

Can we try a car analogy?

You probably have problems with time, too... "Each bag of wood takes 1 minute and 45 seconds to fill. How long will it take to fill three bags?" "Uh, uh, OMG, that's not BASE TEN!"

And ferpetesake, what are you going to do about combining partial cases of beer? Sheesh. Way to hose up the critical issues of the modern age!

Re:BASE16

[Anonymous Coward]

It's pretty easy, just set it up like you would a decimal, quick do 3967^2 (shouldn't take more than 2 seconds. :P)
Probably can do the base16 one faster on paper then 3967. Base16 you keep doing less work when compared to base10 as the numbers get larger.

All you need to know is your base16 multiplication tables to 16x16. In base10 a child can easily multiply a number that is 7 digits or longer, but really as you do the math on your paper you are just breaking it down to your basic multiplication table.

Re:BASE16

[SwordsmanLuke]

0xFA0^2 = 0xFA0 Or did you mean pow(0xFA0, 2)?

Re:BASE16

[zill]

GP really loves pies, apparently.

Re:BASE16

[KiloByte]

But then, a marketing department of a $commodity producer will come and try to redefine that. And we'll end up with monstrosities like kibigrams.

Re:BASE16

[wurble]

I'm gonna take a modpoint hit for this probably but....

1/5 in binary is: 1/101 = 0.001100110011 ... repeating. That's not 1.

2/5 in binary is: 10/101 = 0.011001100110011 repeating. Also not 1.

3/5 in binary is: 11/101 = 0.1001100110011 repeating. Not 1.

4/5 in binary is: 100/101 = 0.11001100110011 repeating. Again, not 1

BUT! When you add 1/101 to 100/101 you get ... 0.11111 repeating, which actually equals 1. Which is correct. Nifty.

Re:BASE16

[Tumbleweed]

Yes, but 16 is easier to carve up into smaller pieces using fractions.

Base 120 FTW!

Re:BASE16

[Anonymous Coward]

Humans use base A, actually.

Re:BASE16

[Anonymous Coward]

Except 1/3 != .333...repeating, we just have no real way to represent it in base10.

Okay smartass, if the people with doctorates who spend their time studying maths don't understand then why don't you explain it for us.

If I have a ruler that is .99999<insert infinity 9s here> feet then how long is that ruler? Please pay specific attention to how the length given is INFINITE and the universe itself has FINITE (i.e. not infinite) bounds. While you're at it, you can explain how infinite sums are wrong despite being used frequently: sum(n=1->inf)[1/(2^n)] = 1.

I don't know what you idiots do that makes you feel more clever than everyone else but I hate to break it to you: decimal representation is arbitrary, it only exists via definition of rules (what mathematicians call axioms) and therefore works as defined, not as what you think is intuitive or not. Really, of all the corner cases in Number Theory you complain about that one? What about division by zero?

If it irks you so much, feel free to define your own number system but don't be surprised if no-one wants to give up the system with known idiosyncrasies for a new one with unknown issues.

Then you have all these math professors with "Doctorates" going around saying...

Yeah, and all these people going around talking about this stupid "color" concept, I'm colorblind and don't see any colors! What idiots they must be!

Re:BASE16

[phyrexianshaw.ca]

... I hope you didn't just mis-convert FA0 to 3967.

it's 4000^2. a simple test for a fourth grader that knows how to factor 4*4=16, 16*1,000*1,000 = 16,000,000.

the hex table for shifting factors of 16 are a pain. (IMHO)

Re:BASE16

[Idarubicin]

Let's say a bag of wood weighs 8 pound 9 ounces, and you want to buy 3 bags. What is the total weight in pound and ounces?

24 pounds, 27 ounces. Piece of cake.

Versus, you have 8.9kg of wood, and you want to buy 3 bags, what is the total weight in kg?

Twenty-four, plus twenty-seven, er, move the decimal, carry the two, ah...damn. Why does metric have to be so bloody difficult?

Re:BASE16

[Anonymous Coward]

Let's say a bag of wood weighs 8 pound 9 ounces, and you want to buy 3 bags. What is the total weight in pound and ounces?

24 lbs, 27 ounces

Re:BASE16

[mangu]

Alas, I can't find anyone around here who sells wood in bags. Metric or otherwise.
I can get it by the cord, by the board foot, or the stick.
Can we try a car analogy?

OK, let's try:

Let's say a bag of cars weighs 8 pound 9 ounces, and you want to buy 3 bags. What is the total weight in pound and ounces?

Hmmm, no. Doesn't work much better.

Re:BASE16

[Anonymous Coward]

This old ditty. But there is no number between .9999 ... repeating and 1. Therefor .99999..... is 1 !!!

What? .aaa...

Re:BASE16

[Anonymous Coward]

25 lbs, 11 oz.

Calculated in my head:
9 oz * 3 = 27 or 1 lb. 11 oz
8 lbs * 3 = 24 lbs
Add them for the total.

26.7 kg (9 * 3 = 27, then subtract 0.3).

Re:BASE16

[marsu_k]

You know, I've heard of this magical invention called decimals. Probably just a myth though.

Re:BASE16

[Anonymous Coward]

Computers use base 2, humans use base 10.

Not in American politics.

Re:BASE16

[Eudial]

'pow' is a floating point function. Clearly you don't expect people to do hexadecimal floaing point calculations in their head?! (Actually, in this case it's fairly easy, but in general, it's more of a headache)

Re:BASE16

[newcastlejon]

Clearly you don't expect people to do hexadecimal floaing point calculations in their head?!

No, Mr. Bond, I expect you to 0xD1E!

Re:BASE16

[cynyr]

and how to memorize arbitrary unit conversions....

quick, how many kgs is 1672mg?

right divide by 100, so 1.672kg. By having all the units be powers of ten, it makes it easy to do unit conversions. Just try cutting a recipe in half some time, how do you measure 1/6th of a cup of milk(2tbsp + 2 tsp). 40mL on the other hand is easy to measure.

Re:BASE16

[Anonymous Coward]

partial cases of beer can be combined by pouring them into larger containers (bags? heh)

Re:BASE16

[Anonymous Coward]

No I didn't mis-convert it to 3967 that was just a number I picked out of the air. You "arbitrarily" picked an easy number to do in base10 though with 4000.

In base16, 1000 is 4096 in decimal.
Look, 1000^2 is 1,000,000 or 16,777,216 (24bit) in decimal

Just adding 0s to 1000^2 works in base16 just as well as it does in decimal. ;-)

100 =256
100*100 still equals 10,000 in base16. ;-)

The properties of multiplication don't magically change just because the place values can hold more or less.

Re:BASE16

[TangoMargarine]

No Mr. Bond, I expect you to die!

Re:BASE16

[EsbenMoseHansen]

60 would have the same divisors except 120 itself....

Re:BASE16

[Anonymous Coward]

It's easy: 0xFA0 ^ 2 == 0xFA2.

Re:BASE16

[EsbenMoseHansen]

Sure you mean that each bag take 1.05 decaseconds to fill?

Re:BASE16

[fbjon]

Then you have all these math professors with "Doctorates" going around saying .9999... repeating really = 1. Except 1/3 != .333...repeating, we just have no real way to represent it in base10.

Argh, this again. There are many perfectly good and precise ways of representing that number in base10. Here's three:

1. 0.(9)
2. 0.99...
3. 1

There you go.

Re:BASE16

[Anonymous Coward]

quick, how many kgs is 1672mg?

right divide by 100, so 1.672kg [...]

0.001672kg == 1.672g == 1672mg

Re:BASE16

[man_of_mr_e]

Decimals are typically only used in scientific and mathematic situations.

That's why the metric system invented many different kinds of "whole" units, which are in effect decimals, but allow people to treat them as if they aren't.

Why do you suppose that is? Most likely because the human brain, unless you've had years of training, doesn't think in decimals.

If you're a carpenter, you're not dealing with .25 of an inch, you're dealing with 1/4 inch. If you're a mechanic you don't have a .125" wrench or a .01 meter socket, you have an 1/8th inch wrench, or a 10mm socket.

Re:BASE16

[Tumbleweed]

60 would have the same divisors except 120 itself....

You sure about that? You might wanna check...

Re:BASE16

[inerlogic]

ok, how many microfarads is 100 nanofarads?

you, i don't know either, good thing for google and it's unit conversions....

Re:BASE16

[Muad'Dave]

I had a college professor that insisted on using nanofarads back when no one had ever heard of such a thing. he was a physicist and naturally had no respect for established norms in electronics. Back then they were just beginning to use uF and pF vs mF for microfarad and mmF for picofarad.

Re:BASE16

[kenboldt]

too long; didn't read? or incapable of understanding do to lower than average intelligence?

Weight a minute...

[Anonymous Coward]

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?

Re:Weight a minute...

[XanC]

Because this prototypical kilogram is what the definition of the pound is currently based on.

Re:Weight a minute...

[sexconker]

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.

Re:Weight a minute...

[Anonymous Coward]

I like how $arbitrary_measurement_unit_1 is more "primitave" than $arbitrary_measurement_unit_2. This amuses me greatly.

Now, if it were "less sensible" or "part of a system that makes less sense", maybe that wouldn't make me laugh as much at your attempt at a comment.

Re:Weight a minute...

[Wyatt Earp]

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.

Re:Weight a minute...

[Anonymous Coward]

The US cares that much why? Its only a trade matter, as we still use primitave imperial measurements.

There are scientists in the US and, mostly, they use standard units of measurement. So they care.

Re:Weight a minute...

[blair1q]

It's hardly a trade matter as no shipment of anything (other than platinum-iridium reference cylinders) has ever depended on that level of accuracy.

It's an anal-retentive comparative science matter. The only people who could care are those who come up with different answers because their nearest reference cylinder was not the same exact mass as someone else's.

Re:Weight a minute...

[goodmanj]

Because a pound is defined as exactly 0.45359237 kilogram, by international agreement since 1959. D'oh! We've secretly been using the filthy metric system all along!

Re:Weight a minute...

[Anonymous Coward]

Wait, so the non-metric system is now defined in terms of the metric system?

Wow, seriously, why are we holding out at all.

Re:Weight a minute...

[jonbryce]

The Weights and Measures Act 1963 -
The yard or the metre shall be the unit of measurement of length and the pound or the kilogram shall be the unit of measurement of mass by reference to which any measurement involving a measurement of length or mass shall be made in the United Kingdom; and- (a) the yard shall be 09144 metre exactly; (b) the pound shall be 045359237 kilogram exactly.

US law says the same thing.

Re:Weight a minute...

[XanC]

But this situation means there's no reason to NOT hold out. Everybody agrees on the definitions, they just use different ways to express the same measurements. Agreement on the fundamental definitions is what's important, and we have that.

Re:Weight a minute...

[smellsofbikes]

Wait, so the non-metric system is now defined in terms of the metric system?

Wow, seriously, why are we holding out at all.

Well, seeing as the English system of weights and measures has been defined by the metric system, legally and factually, since 1893 -- more than a hundred years ago -- and in practice, for maybe thirty years before that, I'm going to guess the answer to your question is inertia and cultural resistance to change.

Re:Weight a minute...

[phyrexianshaw.ca]

One can easily argue this, simply based on the definitions behind each unit of measure. the Kilogram is based on a value anyone can determine (with enough equipment)

while the Troy Pound was: 5,760 Grains. most global pounds became based on troy pounds, defined by how each commodity was weighed against the troy pound.

if you didn't have a troy pound to compare against, it's not like you can just grow 5760 grains and assume you'll get the same weight. (though for the barter system, people would likely have assumed you pound to be of the same value as another's. the grains are just as useful!)

Re:Weight a minute...

[DragonWriter]

The US cares that much why? Its only a trade matter, as we still use primitave imperial measurements.

No, we don't.

First, because the pre-metric US system was the "US customary" system, not the "imperial" system, though some US customary units are the same as imperial units and other US customary units have the same name as imperial units despite being different (e.g., the US gallon vs. the imperial gallon.)

But, more importantly, because, since 1893, most of the units of the US system have been defined as derived units based on the units of the metric system (revisions to the precise definitions have occurred since.)

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?

The relation between the US system and the metric system is pretty much analogous to the relationship between JRuby and Java. The underlying (metric system/JVM) is invisible to casual users, but the the exposed (US system/Ruby) system is completely dependent on the underlying system.

Re:Weight a minute...

[Anonymous Coward]

... but we loose the pound accuracy in the floating point conversion.

I'm willing to bet the epsilon of 64-bit floats is greater than the amount of variability in that big hunk of metal.

Re:Weight a minute...

[RCGodward]

It's a socialist conspiracy I tell you!

Re:Weight a minute...

[fiannaFailMan]

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?

ZanC's informative post about the current setup tells me something I didn't know, but a pound used to be the weight of a pound of gold kept in the Tower of London. It's where the British currency gets its name from since every pound issued by the Bank of England used to be backed by a pound of gold.

Re:Weight a minute...

[thetoadwarrior]

Because the US does indeed use metric but for serious work. I think they only keep the old imperial method to appease the lazy and old.

Re:Weight a minute...

[Anonymous Coward]

You're wrong. Look up survey feet.

Re:Weight a minute...

[Anonymous Coward]

Didn't they stop using Troy pounds after the Greeks burned down the city and killed all the trojans?

Re:Weight a minute...

[shutdown -p now]

Wait, so the non-metric system is now defined in terms of the metric system?

Been like that literally for ages, in fact, though the definitions have updated since it was first introduced.

The reasons to do so are twofold: first, metric units are used by pretty much everyone else, so having a fixed, well-defined conversion ratio is convenient.

Second, metric units have very strict physical definitions, so it's easier to piggyback on that rather than to come up with your own. Imperial units were tied to physical objects, which are a pain to maintain, and still don't give sufficient precision for many scientific purposes.

Wow, seriously, why are we holding out at all.

Because redefining Imperial units in metric ones didn't change anything in practice for most people, so they didn't have to relearn. Inch used to be almost 2.54cm, and now it's exactly 2.54cm - do you really care either way?

Re:Weight a minute...

[Muad'Dave]

(a) the yard shall be 09144 metre exactly; (b) the pound shall be 045359237 kilogram exactly.

They tried to define them in OCTAL??? I see some 9's in there. FAIL.

Did the OP even read the NIST doc?

[walmass]

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.

Re:Did the OP even read the NIST doc?

[UnknowingFool]

Yes, NIST is just following up on an international proposal. The Comite International des Poids et Mesures in 2005 already proposed replacing the kilogram mass with something else.

Re:Did the OP even read the NIST doc?

[Anonymous Coward]

Is there anything in this universe that doesn't decay over time? Unobtanium maybe?

Re:Did the OP even read the NIST doc?

[Anonymous Coward]

They've had problems adhering to the international standards for decades, this measure will just confuse them more.

Re:Did the OP even read the NIST doc?

[KDR_11k]

The point is to find a method for creating kilogram objects without needing a reference prototype at hand so no matter what happens to the existing prototypes you can always build a new one.

Re:Did the OP even read the NIST doc?

[DerekLyons]

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.

Nor is it new(s) particularly. That the physical standard 'drifts' has been known for some time - and researchers all over the world have been studying potential replacements, with the long term goal of getting rid of the last physical standard and replacing it with something natural and universal. (In the way that the meter bar has been replaced by a number of wavelengths of a specific frequency of light.)
 
The only real 'news' in the article is to be found near the bottom - where we're informed the US plans to formally propose a replacement standard.

old, and not just the US

[Imabug]

seriously, this is pretty old. physicists working in metrology have been working to redefine the kilogram for at least the last few decades

Re:old, and not just the US

[gfreeman]

Metrology? Heretic! It's Standardology. Don't be trusting no metric.

Re:old, and not just the US

[blair1q]

If it takes any of them more than 30 seconds to find the solution, they're suck for physicists.

Re:old, and not just the US

[Anonymous Coward]

Weren't the 'Imperial Tones' a British group from the 80's?

Best of Both Worlds

[Anne_Nonymous]

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.

Re:Best of Both Worlds

[pyser]

That's it! Define a kilogram in terms of pints. Now, the quandary: ale or lager?

It makes as much sense to define a kilogram as some huge number of moles of banana pudding or something like that.

Re:Best of Both Worlds

[rjstanford]

Wouldn't a mole made out of banana pudding degrade pretty quickly itself?

And how could it burrow?

Solution fail. Tasty, tasty solution fail...

Re:Best of Both Worlds

[Wyatt Earp]

On 7 April 1795, the gram was decreed in France to be equal to “the absolute weight of a volume of water equal to the cube of the hundredth part of the meter, at the temperature of melting ice.”

So why not switch that to beer? Lager, Porter or Bock is a better question than Ale or Lager.

Re:Best of Both Worlds

[monopole]

The Kilogram is obviously far too French. They will obviously attempt to socialize it by redefining it as how many baguettes of cheese a surrender monkey can eat.

Re:Best of Both Worlds

[jonbryce]

Because it depends on the atmospheric pressure the water / ale / lager is stored in, and pressure is measured in kg/ms^2.

Re:Best of Both Worlds

[Anonymous Coward]

It's got to be special brew. That stuff will never decay over time.....

p.s. Kudos to the guy who wrote the catcha software. 'northern' for this post.....

Re:Best of Both Worlds

[dkleinsc]

I think it's safe to say that banana pudding isn't a solution at all - maybe a suspension is you put in a lot of water, but usually more solid that that.

Re:Best of Both Worlds

[Anonymous Coward]

What about armadillos? Crunchy on the outside, smooth on the inside. Armadillos!

Re:Best of Both Worlds

[robthebloke]

is that baguettes per second, month, year, or lifetime?

Re:Best of Both Worlds

[Anonymous Coward]

excellent idea. How about each american kilogram = 453 metric grams. That way I would not have to buy a new bathroom scale ...

Re:Best of Both Worlds

[shutdown -p now]

American units of measurement have been defined in terms of metric units since 1893.

Speaking as a metric man

[Max Romantschuk]

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.

Re:Speaking as a metric man

[Anonymous Coward]

then how do you define a liter?

OH I JUST BLEW YOUR MIND

Re:Speaking as a metric man

[jaymz666]

litre

Re:Speaking as a metric man

[nizo]

Why the amount of water that weighs 1kg of course!

Re:Speaking as a metric man

[clgoh]

10cm x 10cm x 10cm

Re:Speaking as a metric man

[mark-t]

1000 cubic centimeters.

Re:Speaking as a metric man

[guruevi]

The amount of pure water under regulated conditions that fits in a cubic decimeter. The meter is derived from the speed of light in a vacuum (Wikipedia or Google the exact amount).

You guys really needed to have paid better attention in your 4th grade physics classes, this is quite basic (a good question for "Are you smarter than a 5th grader?"). Oh, you're American, never mind then.

Re:Speaking as a metric man

[blair1q]

It's the amount that fits into a cube that has a side equal to N wavelengths of light from the relaxation transition of atom X.

Oh I just stepped on your dick!

Re:Speaking as a metric man

[WastedMeat]

As an American and a physicist, I would like you to define "regulated conditions" without using mass (The primitive units for pressure are kg / s^2 / m. ), but I would like it more if you were just modded troll.

Re:Speaking as a metric man

[John Hasler]

> Oh, you're American, never mind then.

So am I. It was covered in my elementary school in the 1950s.

Re:Speaking as a metric man

[phyrexianshaw.ca]

this is flawed. you only know it's equal to 1 kg at an exact temperature.

http://en.wikipedia.org/wiki/Properties_of_water#Density_of_water_and_ice

good luck measuring that to any degree of accuracy beyond three or four decimal places. just because you know how much of something you SHOULD have, does not mean you know how much you DO have.

Re:Speaking as a metric man

[xenoglossy]

Oh, not to be a pain but it isn't the weight, it is the mass.

Re:Speaking as a metric man

[Anonymous Coward]

That is also how I estimate kilograms! The physical mass is unreliable - of course that's what they said about YO MOMMA.

Re:Speaking as a metric man

[Anonymous Coward]

It's fairly arrogant to assume everyone writes the same as you (or should).

Re:Speaking as a metric man

[Darkman, Walkin Dude]

Oh piss off you spellchecker abusing malignancy.

Re:Speaking as a metric man

[selven]

1 L = 1 dm ^ 3 = 3.711401 * 10^-29 light-seconds ^ 3 = 28.83085 light-(periods of cyclic radiation from cesium) ^ 3

Re:Speaking as a metric man

[david.given]

So, um, does this all really matter? In practice, that is.

Yes, vitally so --- consistent units are the basis for all engineering, and a lot of SI units are defined in terms of the kilogram. As the various IPKs around the world all slowly diverge in mass from each other, it becomes less possible to know what a kilogram actually is. As the error increases, our ability to measure things gradually degrades, which means that there's more and more error in our machining.

Re:Speaking as a metric man

[DerekLyons]

So, um, does this all really matter? In practice, that is.

Directly in your day-to-day life? Not so much. Indirectly? Overwhelmingly so.
 
That computer you're sitting at? The materials in it are specified by weight. The same for the concrete in the bridge you drove over on your way home. And the metals in the car you drove across that bridge. Etc... Etc... (You can't specify by volume as volume changes with temperature and density, except for a vanishingly small fraction of a percent variation caused by gravity, weight is invariant.)
 
For the pedants whose cursor is even now hovering over the 'reply' button: Yes, I know there's a difference between weight and mass - but for most normal purposes, like building a bridge, they can be treated as interchangeable. Don't get picky just to karmawhore.

Re:Speaking as a metric man

[Anonymous Coward]

Does it matter? Only when dealing with matter. Seriously, though, imagine a calculating the trajectory of a space mission using the wrong mass equivalent for a kilogram. What could go wrong? Well for starters, you might bypass a whole planet, say as big as Mars.

Re:Speaking as a metric man

[rossdee]

"The meter is derived from the speed of light in a vacuum "

Dyson, Hoover, or Kirby?

Re:Speaking as a metric man

[SpectreBlofeld]

Unfortunately, the international standard kilogram of water decayed even faster than the metal brick when it evaporated.

Re:Speaking as a metric man

[Urkki]

As an American and a physicist, I would like you to define "regulated conditions" without using mass (The primitive units for pressure are kg / s^2 / m. ), but I would like it more if you were just modded troll.

"Regulated conditions" could be "triple point of water". That's already used for example for Kelvin scale.

So one kilogram would be X cubic centimeters of pure liquid water at triple point of water. X would fall very close to 1000, but I don't know how close. Also other phases of water could be used I guess, but liquid phase would be the best for practical purposes, I believe.

Re:Speaking as a metric man

[cynyr]

at which temp and pressure? how deep is the 1000 cubic centimeters, as the bottom will be at a higher pressure than the top.

Who cares?

[tarsi210]

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.

Re:Who cares?

[paranoid123]

I think the American Association of Cocaine Dealers would object to arbitrarily getting rid of the kilogram!

Re:Who cares?

[skids]

You totally stole my comment. Or saved me the effort. Or whatever.

Re:Who cares?

[rjstanford]

If you're dealing in kilos rather than grams, I think you can hire people to figure it out. So do what you will with the kilogram - just don't change the gram, and we're all good!

Re:Who cares?

[Anonymous Coward]

It's the US of A -- we don't use the kilogram anyway. Change it as you like.

But we do. The pound is defined as 0.45359237 kilograms, exactly.

Re:Who cares?

[geekoid]

Please, it's used i a lot of places. My kids learn metric in grade school. In fact, just the other day my son referred to a distance a centimeters. in casual conversation.

Re:Who cares?

[cool_arrow]

Without cocaine and weed so many american kids would know absolutely nothing about the metric system. Think of the children!

Re:Who cares?

[tarsi210]

Touché, pussycat.

Re:Who cares?

[garcia]

They'd prefer that the weight continues to degrade.

Re:Who cares?

[Anonymous Coward]

Seeing as you still posted, I'm voting for not saving you effort.

Re:Who cares?

[nschubach]

So that's why they aren't legalizing it... we are sticking to SAE and that's the end of it!

Re:Who cares?

[nschubach]

In fact, just the other day my son referred to a distance a centimeters. in casual conversation.

And some kid didn't come out of the bushes, punch him, call him a nerd, and run off?

Re:Who cares?

[MBGMorden]

Eh - kinda sorta. We learned metric in elementary school too (and that was 20+ years ago), but it's a skill that faded fast. Heck when I went to work with my dad (a construction) worker as a kid and once read off a measurement he asked for in centimeters, I was scolded. Same when I read a fraction once as "fourths" (rather than "quarters").

The thing is, at this point most of my familiarity with metric is more like a quick point of reference based on a version of imperial. I know about how big a cm is, but in my mind it's "A little less than half an inch". A meter? A little more than a yard. A liter is "about a quart".

Overall though, I don't see the problem with imperial. Sure, we're the oddballs compared to the rest of the world, and you don't have the powers of 10 thing, but it's not as if we're using cubits. Imperial units are standardized and work fine.

Re:Who cares?

[Tangentc]

I think the American Association of Cocaine Dealers would object to arbitrarily getting rid of the kilogram!

We PREFER the term American Chemical Society.

Re:Who cares?

[RCGodward]

Not that I'm all that in the know, but I thought it was generally purchased by the ounce, or fractions thereof.

Re:Who cares?

[Anonymous Coward]

When I was in high school, weed was measured in ounces.

Cocaine and other powders though, yeah, totally metric.

Re:Who cares?

[Anonymous Coward]

What are you talking about? Round here all weed is measured in ounces, since that's what the law uses.

Re:Who cares?

[fl_litig8r]

This reminded me of an Onion story on America's inner-city youth's proficiency with the metric system: http://www.theonion.com/articles/metric-system-thriving-in-nations-inner-cities,458/ And yes, the first thing I thought when I saw the weight of the kilogram was in question was the effect on the drug trade.

Re:Who cares?

[Jeff DeMaagd]

Without cocaine and weed so many american kids would know absolutely nothing about the metric system.

We still have guns (9mm), liquor (commonly 750 milliliters) and soda bottles (two liters). Probably other things too.

Re:Who cares?

[riker1384]

Indeed, the metric system is thriving among inner-city youth: http://www.theonion.com/articles/metric-system-thriving-in-nations-inner-cities,458/

Re:Who cares?

[xded]

Imperial units are standardized and work fine.

Sure they do.

Most of the times.

Re:Who cares?

[MBGMorden]

An accident caused by an improper CONVERSION. It's not like a variance in imperial units or some imprecision was at fault.

What you have there is a simple math coding error. The fact that it occurred during a unit version is, in the end, unimportant. A similar area in any other math operation in the software could have had the same results.

Re:Who cares?

[The Clockwork Troll]

Are you kidding? After hard drive manufacturers, there is not a group more eager to adopt the kibigram.

Re:Who cares?

[Anonymous Coward]

what is 'an eighth'?

Re:Who cares?

[spauldo]

California police aren't supposed to bother you if you have less than a certain amount of pot, measured in ounces. I believe a lot of the states that have medical marijuana limit possession to a couple ounces at any one time. Only the DEA seems to measure weed with the metric system, which may reflect the fact they work quite a bit trying to stop importation.

Around here (Oklahoma), I believe it's still sold in ounces and quarter ounces. I never got a consensus on what a "dime bag" was actually supposed to be.

So if you want your kids to learn the metric system, skip pot and introduce them to cocaine.

Re:Who cares?

[ShortRound]

A dime bag is how much you get for $10. How much you get depends on the quality of the weed.

Re:Who cares?

[xded]

For sure. I was meaning that pretending you can stick to imperial units, like LM did, is not always working.

Re:Who cares?

[Maggu]

The pound is defined as (exactly) 0.45359237 kilograms. If the kilograms gets lighter, the pound gets lighter. If the kilogram gets heavier, the pound gets heavier.

The difficulty of standard artifacts

[Homburg]

"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

Re:The difficulty of standard artifacts

[goodmanj]

Very clever, Mr. Wittgenstein. Unfortunately shortly after you died we defined the meter in terms of the speed light travels in a certain amount of time, and abandoned the Paris standard meter. So one thing can be said for sure: the Paris standard meter is definitely *NOT* one meter long."

Re:The difficulty of standard artifacts

[Anonymous Coward]

Meter changed a long time ago to be some number of oscillations of photons from some atomic spectrum.

Re:The difficulty of standard artifacts

[zzsmirkzz]

yes, but through which medium?? Light can be slowed down/delayed/absorbed & re-emitted or however you want to say it, which can have a significant effect on the linear distance it travels.

Re:The difficulty of standard artifacts

[Anonymous Coward]

"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

You can say my dicks one meter long. Booya mothafucka!

captcha: outwit - i outwit you

Re:The difficulty of standard artifacts

[mdielmann]

yes, but through which medium?? Light can be slowed down/delayed/absorbed & re-emitted or however you want to say it, which can have a significant effect on the linear distance it travels.

The same rules we use for c: The speed of light in a vacuum.

Re:The difficulty of standard artifacts

[zzsmirkzz]

I understood that to be the definition but how do you actually apply that definition in practice to construct say a meter-stick that is exactly one meter??

Re:The difficulty of standard artifacts

[Anonymous Coward]

You're trying to look intelligent, but if you actually were you wouldn't be asking this question since the guys who defined it were intelligent and defined it against the speed of light in a vacuum

Re:The difficulty of standard artifacts

[Anonymous Coward]

I'm quite sure that it is sometimes actually one meter long, i.e. if it reaches just the right temperature or the right temperature gradient across its length and you measure just across the right bits from both ends.

I think I need more coffee

[Anonymous Coward]

I read the title as "US Objects To the Klingon". @.@

I suspect that all the fuss...

[Slutticus]

..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.

Re:I suspect that all the fuss...

[SydShamino]

No, but every NIST-traceable instrument eventually gets back to those standards. Sure, there are a very small number (probably a dozen or so) weights directly calibrated against the original articles. But then those are used to calibrate a few hundred weights at metrology labs, which are used to calibrate weights for thousands of customers around the world. Each step introduces uncertainty, but uncertainty around a precise value can be accounted for. Uncertainty around the wrong value renders the instrument useless.

The same is true for other standard units. I have instruments at my desk that are calibrated and NIST-traceable for time and voltage.

Re:I suspect that all the fuss...

[Carnildo]

..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.

The official prototype kilogram (IPK) has drifted relative to the average of its copies by 40 parts in a million, and relative to one of the copies by over 120 parts per million. The best scale you've got at home is probably good to no more than one part in a hundred, but it's common for laboratory scales to be good for one part in 10,000 (enough to detect the difference between the IPK and K23), and scales good to one part in 100,000 aren't uncommon.

Re:I suspect that all the fuss...

[hedwards]

Right now perhaps, but changes like this tend to deviate more and more over time making it a much bigger deal in the future than it is right now. Units do change from time to time in response to science.

What?

[rdg55]

--Physicists may scoff at the thought people allowed to walk among the living who don't know what a Planck value is.-- I scoffs @ the writers grammer.

Re:What?

[Anonymous Coward]

--Physicists may scoff at the thought people allowed to walk among the living who don't know what a Planck value is.--
I scoffs @ the writers grammar.

FTFY

Re:What?

[kenboldt]

--Physicists may scoff at the thought people allowed to walk among the living who don't know what a Planck value is.-- I scoffs @ the writers grammer.

I'm sure you meant writer's grammar with the appropriate apostrophe in writer's and an "a" in grammar and not an "e"

Re:What?

[rdg55]

You missed the improper conjugation of scoff. And the sarcasm. Did you also miss the missing word in quoted sentence? Look closely between "thought" and "people". Grammer is pretty standard in grammar-scoffing posts. It be comedy 101.

Why the sensationalism ?

[Anonymous Coward]

It is just a scientific opinion from a group of scientist who happen to work for an institution funded by federal dollars. Nothing to do with the adoption of SI units by the US - which of course is a sensational.

I betcha...

[drunkennewfiemidget]

One of the scientists is just fat and wants to redefine the kilo to be a bit bigger so he weighs less.

It beats NOT eating Double Downs.

Shitty Fox Article

[dcollins]

That is one super-shitty Fox article that's been chosen to base the headline here on.

FTA: "...now NIST plans submit what amounts to a formal complaint at next October's General Conference on Weights and Measures -- along with a proposal to define a new kilogram according to something called a Planck value... Physicists may scoff at the thought people allowed to walk among the living who don't know what a Planck value is. But all you need to know is, they're using it to determine the mass of one mole of silicon atoms."

Yeah: Bullshit and more bullshit.

Re:Shitty Fox Article

[blair1q]

Yes, because at present the mole is defined as the number of atoms in 12 g of C-12. So if they want to define the kg in terms of the mol, they're going to have to fill out the rest of the digits in Avogadro's number first, and arbitrarily dictate that as the one true number for all time.

Which is fine, really, because the arbitrary determination that a kilo is the weight of one liter of water, translated to a platinum-iridium cylinder of some dimensions by some over-enthusiastic eaters of frogs' legs at some time in the past, is what we're going on now.

I for one am curious as to what the hell the Planck length has to do with it.

Re:Shitty Fox Article

[hedwards]

Indeed. Everybody knows that a Planck value is whatever you demand in lieu of making them walk the Planck. Duh, I thought everybody knew that.

No more gold standard

[countertrolling]

We're going to let the kilogram "float" and put it on the commodities market. It should triple the value of the gram

Re:No more gold standard

[flaming error]

Fractional Reserve Physics FTW!

Re:No more gold standard

[tool462]

Awesome! That's why Americans weigh so much more than their European counterparts. It's not obesity, it's inflation!

Say what?

[mark-t]

Why is the US objecting to a standard that it has not ever taken the time to actually use? Talk about anything in metric to most anyone from the US and they go "what's that in English?" Argh!!!!

That said, I am compelled to agree with the reasons for the change... hopefully the new value is close enough to the old that not too much should require updating (I'm thinking the most likely candidates for updates are books in astrophysics).

Re:Say what?

[dondelelcaro]

Why is the US objecting to a standard that it has not ever taken the time to actually use?

Anyone in the US who actually does quantitative research uses the metric system. I can't remember the last time I attempted to mass something in pounds.

Re:Say what?

[Wyatt Earp]

Learn some history of the Metric System and the United States.

http://en.wikipedia.org/wiki/Metrication_in_the_United_States#19th_century

Everything the Federal Government does is in the Metric system, sometimes it's converted to United States customary units.

The US Military has been metric for ages, weapons, distances, weights are all metric.

Hell, half the parts of my truck are metric and it was built 20 years ago.

Re:Say what?

[tie_guy_matt]

All customary units used in the US have long since been defined to link to their metric counterparts. So if the mass of a kilogram changes (kilogram is a mass not a weight) then that means the mass of a customary US slug will also change (this will also change the weight of a US pound.)

Note that we use watts quiet a bit in the US. A watt is really equal to a kg m^2 s^-3. So if you change the definition of kg you change the definition of watts as well as a lot of other derived units.

Re:Say what?

[hedwards]

Because the pound is specified as being a certain amount of Kilograms, rather than an independent measure as it used to be. So if something happens to the kilogram, then something happens to the pound. Simple really.

Re:Say what?

[rec9140]

"..."Everything the Federal Government does is in the Metric system, "

Yeah and its a PITA!

THe FCC is good for this crap... every thing in the ULS tables is in !!(!(*@^$!^ ! non standard units and has to be converted back when I process it into my local version on MySQL system...add in fact that they don't clean up the input which allows for all sorts of crap including CR/LF in text fields! URRRGH The they export it in flat CSV files which then the CR/LF causes a new record ... what a mess. Sanitize the input! Nope the FCC when questioned and reported to them says its perfectly acceptable.. .YEAH sure it is when your on the native DB2 servers at the FCC.... not when your dealing with the exported tables!

I really don't know why any agency in the US would do this... starts to explain the $600 hammers, $1000 toilet seats... at DOD .... you asked for it in some stupid non standard measure so of course it doesn't fit when you asked for a 2cm and you got a 2 inch one. Really makes NO sense for the US GOV to do this when most manufacturing in the US is still done in real standard units. No wonder this crap cost so much.. custom items!.

Re:Say what?

[fiannaFailMan]

Why is the US objecting to a standard that it has not ever taken the time to actually use? Talk about anything in metric to most anyone from the US and they go "what's that in English?" Argh!!!!

The US armed forces work in metric.

I wonder why american scientists care

[MouseR]

...given the bulk of the population doesn't even know what metric is and that they measure distances in football field lengths.

Not quite as retarded as calculating weight in stones, but it`s only a foot away from that.

Re:I wonder why american scientists care

[stiffy]

Don't forget Olympic sized swimming pools...

Re:I wonder why american scientists care

[Wyatt Earp]

We measure distances in inches, feet, yards and miles. The media uses football fields as a alternative to acres when trying to dumb it down.

Re:I wonder why american scientists care

[MouseR]

Yeah, for volumes.

Re:I wonder why american scientists care

[AndrewNeo]

Apparently they care because they're selfish, if everyone else is so dumb?

Re:I wonder why american scientists care

[Moridineas]

How much meaning does acre have for the average person? Not a lot. I live on .25 acres, so I can roughly figure out how big 1 acre is, but it doesn't extrapolate well for me. Then think of your average city-dweller who lives in a townhouse, condo, or apartment and doesn't have a clue what an acre is? Plus house lots (where most people run into acres) are often very irregularly shaped, thus acres aren't even useful for distance.

A football field, on the otherhand, is something that almost all Americas know something about. Even if you've never played football (eg, me) you've been on a football field, watched football, jogged around one, and so on. How about a mile? Almost everybody has experience with miles, driving, etc, but a football field as a smaller unit has the virtue that you can see the entire thing at once. It's very graspable.

I don't see what the problem with using it to make distances/sizes more accessible is? Obviously nobody is advocating doing math or physics using such units, but then again metric has been standard throughout many occupations and the sciences in America for a long time...

Re:I wonder why american scientists care

[Anonymous Coward]

Only in your country, and you've even gone to the lengths of redefining what 'football' means......

Re:I wonder why american scientists care

[fiannaFailMan]

...given the bulk of the population doesn't even know what metric is and that they measure distances in football field lengths.

Not quite as retarded as calculating weight in stones, but it`s only a foot away from that.

What bugs me in the US is that when giving the weight of ships, bridges, aircraft, trucks or other heavy objects, they still use pounds and give you numbers in the millions that quickly become meaningless to the casual reader. What's wrong with tons? Since an imperial ton is not much different from a metric tonne then it's easier for both camps to relate to.

Re:I wonder why american scientists care

[Anaerin]

What's wrong with measuring weight in stones? You convert ounces to pounds when they get large, why not use the next step up?

Thus, rather than being "100lbs soaking wet", you'd be a "7 stone 2 pound (Or '7 stone 2') weakling".

There's therefore 8 stones to a hundredweight, and 20 hundredweight to a ton. Rather than keeping it all in pounds and having 2240 pounds to a ton.

Though the need to remember all these "Magic numbers", which I was always taught is bad in programming, never sat right with me at all. Probably why I prefer metric.

Re:I wonder why american scientists care

[Anonymous Coward]

The standard mass serves as the physical basis for measurement. The goal is to improve the stability of the reference. It is totally irrelevant what units you use whether Kg or Pound or make up your own. The changes proposed have nothing to do with preference or adoption of one of these systems just the long term stability of the calibration source.

Whoosh!

[AmigaHeretic]

Jesus people it was a joke as to the headline of the article, "US objects to Kilogram" and how we still insist on using the pound over the kilogram.

Obviously base16 would be retardedly hard for every day measure for most people.

How many pounds is FCA again grandma?

Re:Whoosh!

[hedwards]

It's hardly just us. When's the last time somebody went into a British bar and offered to pay in Kilos?

Re:Whoosh!

[John Hasler]

> ...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.

Re:Whoosh!

[Anonymous Coward]

Go to a grocery store anywhere in the United States and look for a produce department that sells produce by the kilogram.

WHy does America care

[Anonymous Coward]

They don't even use the Metric system
Shit I am surprised they even know that a kg exists and now that they know it is a french thing they are not going to change

It's true...

[N0Man74]

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

Re:It's true...

[Idarubicin]

For an article on units of mass, I found it disappointing that you forgot Volkswagens.

Re:It's true...

[Anonymous Coward]

- Libraries of Congress

Hey, there's another artifact we need to get rid of. We just have give researchers the means to create their own library of congress.

Re:It's true...

[Chuckstar]

You forgot softballs!

Re:It's true...

[Anonymous Coward]

Well in a general dumbing down, it is quite practical to reference sizes to things people know. However, LoC (=Libraries of Congress) is an odd measurement base. Maybe LoC is used to measure big book assemblies. While everyone knowns one LoC is incredibly big assembly and everything bigger is ridiculous big.

       

Objecting for a long time

[elsurexiste]

They want to replace it with the Pound (badum tss)

um, it's been a while since I took physics

[Anonymous Coward]

but unless my 40+ yr old brain is deteriorating a lot faster than I realize a kilogram has NEVER "weighed" a kilogram - pretty sure a kilogram weighs 9.8 NEWTONS (and that's only at sea level)

am I seriously the 1st /.-er to point this out?

Re:um, it's been a while since I took physics

[Anonymous Coward]

Not to mention that weight is an additional function of another mass...

Re:um, it's been a while since I took physics

[goodmanj]

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.

MASS not WEIGHT!

[Anonymous Coward]

If this whole discussion is about the WEIGHT of one kilogram, as the post suggests, it won't get far.

kilogram is a unit of mass, not weight.

Kilogram is a mass not a weight

[MConlon]

Newton is a weight. The summary (and the Fox article) are incorrect, while the NIST article correctly refers to the reference mass.

MJC

Re:Kilogram is a mass not a weight

[crunch_ca]

Mod parent informative.

I bet if the platinum cylinder were in orbit, the weight would be way off from 2.2 lbs. It would still be a Kg though (not accounting for missing mass discussed in the NIST article).

Re:Kilogram is a mass not a weight

[Anonymous Coward]

It's really sad when a slashdot summary is referring to a kg as a weight. A kg cylinder doesn't change mass under different gravities. It is still 1kg on Mars, 1kg on the moon, and 1kg on Jupiter. A kilogram is a unit of mass!!!!

Re:Kilogram is a mass not a weight

[SnarfQuest]

Since we have the experts here, is a metric buttload a unit of mass, or is it weight, or maybe volume? I know that someone will say is a unit of current, because of all the juice. Others could claim it as a unit of time, due to the length of the queue at many sports events.

Re:Kilogram is a mass not a weight

[Anonymous Coward]

Are you saying a NIST article is more accurate than a Fox article? Who would have thunk it

Re:Kilogram is a mass not a weight

[bmo]

No, a Newton not a weight, it is a cookie.

https://secure.wikimedia.org/wikipedia/en/wiki/Fig_Newton

And too many Newtons leads to weight gain.

--
BMO

Re:Kilogram is a mass not a weight

[jwbing]

No, a Newton is not a cookie. It is fruit and cake.

Re:Kilogram is a mass not a weight

[bmo]

That made me smile. That's an old ad from the dusty passages of time. You can clear out your dusty passages if you consume enough Netwons and drink some coffee. They're high in fiber!

--
BMO

Re:Kilogram is a mass not a weight

[Anonymous Coward]

"A cookie is just a cookie, but a Newton is fruit and cake."

Headline is sensationalist

[starseeker]

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?

Re:Headline is sensationalist

[goodmanj]

This is Fox News. From their perspective, *all* concerns are political concerns.

Global warming, economic policy, genetic engineering, epidemiology: all of these are relevant to Fox News (and MSNBC etc) only for their impact on the great battle between conservatism and liberalism.

Re:Headline is sensationalist

[poena.dare]

Seriously! Can't ./ implement an Article Title metamod system?

Re:Headline is sensationalist

[zippthorne]

It's easy to see how they got it wrong in a sensationalist way, though. In scientific and engineering circles, the reference kilogram used to calibrate other reference kilograms which are then used to calibrate scientific instruments, is often referred to as "The kilogram." Both to emphasize its supremacy over other reference masses, and because it's funny to say.

Also, it feels a little pretentious to keep an object in a well-guarded and carefully constructed vault, whose sole value is in "always weighing the same."

Re:Headline is sensationalist

[Anonymous Coward]

Agreed. In the physics community it has been years that this cylinder is looked down upon (This is NOT NEWS). Basing it upon the measured value of c is better. I thought c in a vaccum would be used instead of planck constant (h-bar). Its easier to plug into equations. Then you can define h-bar in terms of c, by using normalized units instead of mks. In that kind of system you only need one constant to define.
    If you try and measure carbon atoms, or anything you can get quantum effects when they bind together. Ugh... imagine an extra gluon throwing off the measurements, or the energy stored in a chemical bond.... AHHH!
    On the other hand charge is simple, just define it in units of an electron charge which has been very throughly measured and make that the new constant.

Ben Stein?

[Anonymous Coward]

If you look at the NIST release... note whose name is given for the press contact.

I guess they really do have Clear Eyes (TM) in the government. :-)

Calculate decay

[Anonymous Coward]

I suppose those great physicists could always calculate how much the decay means and figure out how much weight the item lost. But somebody please tell me, is this even noticeable ?

Americans missing the point

[chargersfan420]

First and foremost, it must be said that the kilogram is a unit of MASS, not weight. It refers to the amount of space that an object takes up, not its gravitational force. See here.

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.

It is this way because it makes sense, like the rest of the metric system. Unfortunately, somehow it became more common to refer to it as a weight, which just confuses people.

Re:Americans missing the point

[goodmanj]

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.

Re:Americans missing the point

[Anonymous Coward]

Which would be grand, except it's not that way (which wouldn't make sense) -- because of the (obvious, except apparently to you) impracticality of establishing a precise volume of pure water of precise isotopic composition at precise temperature and pressure and getting adequate precision for modern scientific work, it's the mass of the IPK, a chunk of platinum-iridium alloy sitting in a vault in Paris, which was machined to closely match the previous (impractical, water-based) definition. This happened over a century ago, so I'm afraid you're missing the point as much as anyone.

And yes, mass and weight are different (though neither has a damned thing to do with the space it takes up, that's volume. FWIW, most people I know do sometimes use weight for mass in casual conversation, but are aware of the distinction and use them correctly when there's actually risk of confusion; then again, they're not dumb hicks with 120-year old knowledge of SI (i.e. they know the difference between mass and volume, and have even heard about the IPK), so it's understandable that they'd be less prone to confusion than you.

Re:Americans missing the point

[Arthur Grumbine]

First and foremost, it must be said that the kilogram is a unit of MASS, not weight. It refers to the amount of space that an object takes up, not its gravitational force. See here.

You probably should have read this before posting. The amount of "space" an object takes up is called volume.

Re:Americans missing the point

[Anonymous Coward]

It refers to the amount of space that an object takes up, not its gravitational force.

The amount of space an object takes up is referred to as capacity, commonly measured in cubic centimeters, cubic meters, cubic inches, etc. to understand mass, see parent's link. Is there as much "stuff" in a glass of air as in a glass of liquid?

Re:Americans missing the point

[Synonymous Homonym]

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!

Pure water, at 4 degrees Celsius, at 1000 hectopascal.

Re:Americans missing the point

[Urkki]

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!

Triple point of water is awfully convenient for things like that. And obviously it'd have to be pure water of fixed hydrogen and oxygen isotopes. Just measure it quickly, before some stray cosmic ray or a neutron from a nearby nuclear decay changes something!

thanks-

[the_fat_kid]

now you have given me the image of a Klingon in a vault in france.
I'll bet it's decaying. probably smells bad too.

Re:thanks-

[harrkev]

They smell bad even when alive.

Re:thanks-

[the_fat_kid]

the french?

Obligatory pedantic objection

[__roo]

... blah blah blah ... kilograms ... blah blah blah ... measure of weight ... blah blah blah ... mass and weight are not the same thing ... blah blah blah ... measure of force ... blah blah blah ... weight ... blah blah blah ... mass ... blah blah blah ... Earth's gravity ... blah blah blah ...

obligatory Wikipedia link to back up overly pedantic argument

Nyuk

[Anonymous Coward]

Of course it only makes sense to use guacamole, not banana pudding. Then the conversion is a simple computation based on Avocado's number.

Re:US != SI

[blair1q]

Because, in a piece of delicious irony, our Storm Troopers don't use imperial units.

Re:US != SI

[goodmanj]

Because US units are defined as multiples of SI units. The pound, for example, is defined to be 0.45359237 kilogram.

No matter what the local custom is, the SI system *is* the world standard for everything.

BAD headline

[BudAaron]

The headline for this article is so misleading. The US doesn't "object" - NIST and the world simply say it needs to be redefined and I agree.

Good incentive. But I have my reservations.

[Anonymous Coward]

Of course many years after the new kilogram SI unit is in use, the Americans are still going to be measuring weights in pounds, ounces and (non-metric) tonnes.

Re:It's not just the Kilogram

[goodmanj]

Actually, thanks to the drug trade, the kilogram is the one unit we *do* have a good understanding of.

Fox news?

[Anonymous Coward]

If it comes from Fox, it's false!

Question...

[Joce640k]

How does "America" define the pound...?

Re:Question...

[Creepy]

international avoirdupois pound is set to exactly 0.45359237 kilograms... or is it? I guess that's why the US cares if the kilogram loses weight.

Re:Question...

[XanC]

2.20462262 pounds per kilogram. It's defined in terms of the kilogram. If it weren't, there wouldn't be global agreement on weight of things (which there is). This is why the US cares what the mass of the kilogram is.

Re:Question...

[Tumbleweed]

How does "America" define the pound...?

Take one quarter-pounder (with cheese), multiply by four, et voila, one pound. It's so simple, even Glenn Beck can do it! The reason he WON'T do it is because he thinks McDonald's is a Scottish Muslim liberal conspiracy. He'd prefer you eat gold after the whole socio-economic system is destroyed by Obama. Fortunately, after the fall of civilization, Christine O'Donnell will make sure you can't masturbate, and I'm sure that will turn things around very quickly.

Re:Question...

[robthebloke]

1.6018 U.S. dollars

Re:Question...

[PhrostyMcByte]

It's easiest here in the states if you measure in quarter-pounders and double-quarter-pounders.

Re:Question...

[Anonymous Coward]

Oh no! Then our triple-quarter-pounders with extra cheese will decrease! We must protect the American serving size!

Re:Question...

[Anonymous Coward]

How does "America" define the pound...?

...four cheeseburgers.

Classic dupe.

[Joe Snipe]

This is constantly being discussed to death

I remembered it because it had one of my favorite comments

Roundest

[pgn674]

Is this a part of the same effort: Slashdot Science Story | Roundest Object In the World Created?

Re:Roundest

[JSBiff]

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.

One pound of ground beef, please ...

[PolygamousRanchKid]

Customer: "Hi, I'd like one pound of ground beef, please."

Seller: "Um, can you tell me how much that is in Planck values of moles of silicon atoms?."

It's not the mass, it's that it's not decimal...

[Joce640k]

How many ounces in a pound, how many pounds in a hundredweight, how many pounds in a ton? None of those numbers ends in zero...all are a pain to convert.

Definition

[gfreeman]

For 130 years, the kilogram has weighed precisely one kilogram. Hasn't it?

Yes, by definition. If it doesn't weigh a kilogram, then it cannot be a kilogram.

defined by water

[Khopesh]

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.

Water is where the standard came from, but for one reason or another, it was replaced by that platinum brick. I think we now have the scientific expertise to return that that definition. I'd certainly prefer that as well, as it reduces the number of independently defined bases (like the five postulates of Euclid's Elements).

The NIST article has two conflicting statements on that front:

The definitions of the ampere (electric current), mole (amount of substance) and candela (luminous intensity) ultimately depend on the platinum-iridium artifact. For example, a mole is currently defined as the number of carbon-12 atoms whose total mass is 12 grams.

but later, it says

The seven SI base units from which all others are derived are the second (time), the meter (length), the kilogram (mass), the ampere (electric current), the kelvin (thermodynamic temperature), the mole (amount of substance) and the candela (luminous intensity).

So amperes and moles are defined by a (kilo)gram and are therefore not independent. I would assume, based on that second quote, that each of those SI base units was independent...

If grams were once again derived from meters, those "seven" SI base units would actually be four.

Re:defined by water

[zzsmirkzz]

Um, I thought an ampere was defined as a specific amount of electrons passing a particular point in one second. How does that have anything to do with kilograms??

Re:defined by water

[david.given]

Right now the ampere is actually defined as the current needed to apply a certain force in newtons to an object between two conductors; and newtons are defined as the force needed to accelerate a mass of 1kg at 1m/s/s. So you can't know what an ampere is unless you also know what a kilogram is.

Re:defined by water

[zzsmirkzz]

and by extension, the distance between the object and the two conductors must also me taken into account so you must know what both a kilogram and a meter is to determine an ampere, not to mention what a second is. Sounds like quite the fine mess we have gotten ourselves into as we try attempt to work with things with finer and finer precision.

I liked my way better.

Re:defined by water

[Rich0]

The problem with a definition based on water is that it is very hard to use in practice, with high accuracy.

Where do you get the water from? Before you answer, keep in mind that the density of water varies based on its purity, both chemically, and isotopically. The latter is VERY hard to control.

Oh, and measuring a cubic dm of water isn't all that easy either. Sure, you can just build a cubic box and all that, but the problem is that constructing such a box and measuring its dimensions with high precision is difficult.

I think the current trend in density-based definitions is using silicon, as we can make that with very high purity (due to the semiconductor industry), and being solid you dispense with the need for a container/etc. Still, measuring its dimensions/etc is still hard. I'm not sure how they deal with the isotope situation - maybe silicon is found in nature with a higher level of uniformity/etc.

Keep in mind that scientists care about definitions with very large numbers of significant figures. The current artifacts are VERY accurate despite their shortcomings, so for the new definition to be accepted it has to be at least comparable in accuracy. Definitions that are simply more elegant on paper aren't as useful in the real world...

Re:defined by water

[Khopesh]

How is this different from defining it by an artifact locked up beyond your reach? We have the technology to make such precise measurements on all of those fronts, and you'll have to entrust it to experts at a standards body either way you slice it.

Re:defined by water

[Rich0]

How is this different from defining it by an artifact locked up beyond your reach?

It isn't beyond all reach - I just can't access it personally. Sure, that isn't ideal, but it still works, with an acceptable level of error

We have the technology to make such precise measurements on all of those fronts

The problem is that experts don't agree with that statement - at least they didn't a few years ago when I last read up on the problem.

Here is an illustrative example (numbers are illustrative and not exact figures). I propose that a kg is the mass of a piece of metal made a century ago. Based on measurements made over time I have a pretty high level of confidence that it is accurate to about 0.1%, and that its accuracy will decrease over time. You propose that a kg is the mass of a 1000 cm^3 of pure H2O at its triple point (composed of 1H and 16O). That mass of course will never change over time (unless there is something going on with the laws of physics that we don't understand). However, suppose that your measurement technique has a 1% error rate. Your standard is in principle better, but in practice the lump of metal is more accurate.

Now, over time that lump of metal will only get worse as it degrades, and over time the accuracy of your technique will only get better. Maybe at some point in time they're close enough that just the convenience and elegance factor justifies switching. However, my understanding is that right now the accuracy difference is high enough that it doesn't make sense to switch yet. Perhaps this news suggests that this is changing.

From what I've read the problem is that the people who made that lump of metal did such a good job that it is just REALLY hard to surpass it, even if on first principles the lump doesn't make sense.

Re:defined by water

[Rich0]

The meter and the second are both defined in terms of physical standards.

The 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 cesium 133 atom.

The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

Dont give two shits about your pride

[unity100]

i know it feels rather tough for you 'pound' people to leave your odd measurement system and move into metric. but it is ridiculous to try to come up with a 'middle' solution to save your pride. rest of the world is using metric system. deal with it. even if we pass to a system based on particle physics, it is going to be the equivalent of a kilogram. object all you want. the whole world cant change their standards, naming, convention for countries who havent been able to get out of their british empire inherited systems yet. imperial vs the world; the world wins. period.

and no. im not french. get offended as much as you want.

Re:Dont give two shits about your pride

[fotbr]

You didn't read the article, at all, did you? This isn't about the unit, it's about the unit being based on a physical object, that happens to be changing. The proposal is to replace the physical reference with a mathematical definition. And it's an international proposal.

In short, summary fail.

Because you decided to go on a rant based on a bad summary, your rant makes you look like an idiot.

Re:Dont give two shits about your pride

[unity100]

and i dont care about looking like an idiot either. it has gone for so long, that irritating 'imperial measurement' nationalist bullshit has produced these kind of knee jerk reactions on the rest of the world. you reap what you saw.

Re:Dont give two shits about your pride

[nomadic]

Just because your math skills are too weak to convert between different base system measurements doesn't mean we should cater to your mathematical ineptitude.

Re:Dont give two shits about your pride

[nomadic]

So wait, AMERICA'S to blame for YOUR mistake? You have gotta be a European with that attitude.

Re:Dont give two shits about your pride

[unity100]

america should be blamed with their ineptitude of reading comprehension. and im not european either.

NOT Pedantic

[jIyajbe]

It has a mass of 1.000 kg. It weighs 9.806 newtons. (Approximately, depending on the local value of g.)

Anyone who thinks that that is overly pedantic is not a physicist.

Re:NOT Pedantic

[Anonymous Coward]

IAAP, and it's a bit overly pedantic. A real physicist is comfortable defining his units in whatever way seems convenient at the time. Want to set Planck's constant to 1? Speed of light in vacuum to 1? Boltzmann's constant to 1? Knock yourself out. If you want to speak about weights in a system where acceleration due to gravity is 1, that seems ok to me. "This object has a weight of x kilogram-gee." is perfectly sensible. It's equally sensible if we colloquially don't bother to say "gee" every time.

Remember the Mars Lander

[crath]

Not to mention the fact that even NASA scientists can't agree amoungst themselves whether to use metric or non-metric units.

Re:It's not the mass, it's that it's not decimal..

[Anonymous Coward]

I'm pretty sure there are 2000 pounds in a ton. That ends in 3 zeros.

Re:It's not the mass, it's that it's not decimal..

[AltairDusk]

how many pounds in a ton? None of those numbers ends in zero...all are a pain to convert.

2000 doesn't end in zero?

Scientific journalism at its worst

[Anonymous Coward]

The Fox article was bad enough. The sensationalist Slashdot article just adds that much more anti-science to the mix. The difference is: I expect fox news to not know a dang thing about science. I expect better of Slashdot.

Common Courtesy

[TiggertheMad]

Yeah I always wondered why drug dealers sold things in kilos. I mean, when I go to purchase hundreds of thousands of dollars in drugs, I would think that the dealers would have the courtesy to use a unit I am familiar with.

Dear USA

[fincan]

You fucked yourselves up by using your shitty pounds, inches, fahrenheits, feets, X football fields, gallons. Please do not try to mess with our finely defined base 10 measurements and rot in your stupid imperial units.

Re:Dear USA

[nomadic]

Didn't read the article, did you...

Re:Dear USA

[fincan]

Of course I didn't read it, what did you expect? This is slashdot.

Why does the US NST care?

[wealthychef]

I don't think we at the US should get a vote until we switch from the stupid Imperial system.

Doesn't that mean our measurements are off?

[Anonymous Coward]

Ahah!

I knew I wasn't gaining lbs, it's just that our scales are reading more because of the degenerating kilogram!

If we want to be really precise ...

[TheABomb]

nothing weighs 1 kg. A cylinder might have 1 kg of mass, but its weight is something different altogether.

Didn't they do that a long time ago?

[davidwr]

I guess not.

Hmm, I guess all that talk I've heard over the years about giving a definite value to Avagadro's number and thereby giving a clear value to the Kg as 1000/12 of 1 mole of Carbon-12 was just talk.

Yeah

[ratboy666]

Like, the US said, "we caught six kilograms at the border, and detained them". Kilograms are just naturally objectionable; any country should be able to see that, and follow in the USs footsteps.

Except the French, of course -- those whiny buggers just want to WORSHIP the damn kilogram.

Ratboy666

Mass deficit in ppb?

[tepples]

The structure of crystals indeed affects the mass of the crystal due to binding energy and mass deficit.

But how many parts per billion is this mass deficit?

Re:Mass deficit in ppb?

[modmans2ndcoming]

who cares when you are constructing a DEFINITION, not an object?

The mass deficit would be important for a weights and measures engineer when they use the definition to construct an object that will be used to compare mass of one object to that of a reference. It has nothing to do with the definition.

are you going to bitch about the definition of a meter since it uses the distance a photon travels in x/y seconds? I mean... that definition is talking about a perfect vacuum... we don't live in a perfect vacuum... we better go back to a metal rod deffinition for the meter as well!

Re:Mass deficit in ppb?

[jc42]

But how many parts per billion is this mass deficit?

who cares when you are constructing a DEFINITION, not an object?

I'd guess that everyone involved cares, because if the definition doesn't make it possible for the engineer types to actually apply the definition to real objects, the definition will be moot and unusable.

The physics of it all has been known for most of a century, but the (kilo)gram's definition has remained a physical object due to the known difficulties in high-precision construction of masses precise to the desired number of decimal places. It's happening now partly because our ability to do the real-world measurements has surpassed the precision of the physical kilograms masses.

are you going to bitch about the definition of a meter since it uses the distance a photon travels in x/y seconds? I mean... that definition is talking about a perfect vacuum... we don't live in a perfect vacuum...

But we can measure the speed of light to high precision within our atmosphere, and we can measure the atmosphere's index of refraction to high precision. Plug those numbers into the appropriate equation to translate to speed of light in a vacuum.

This is now high-school physics (in some high schools); it's not abstruse stuff limited to a few high-tech labs.

The only real challenge these days is to get Americans to measure themselves - and their roads - in SI units. But we've already achieved the most difficult task: Americans now buy their booze in liters. ;-)

Re:Mass deficit in ppb?

[maxume]

What would it change if Americans measured ourselves and our roads in SI units?

BTW, the bottle of beer I am drinking is 11.5 fl.oz. and 340 ml, neither is particularly more useful as a measure than 'a bottle'.

Absolute definition of weight

[asher09]

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.

From our dept. of redundancy dept.

[grepya]

"US Objects To the Kilogram"

    Who knew ? Also the meter, the Celsius and the liter.

Ben Franklin & precision

[david.given]

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.

Re:Ben Franklin & precision

[geekoid]

we were very close to converting. Reagan killed that, because he need to make it look like he was cutting spending. Fucking douche.

Re:Ben Franklin & precision

[Anonymous Coward]

> 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.

You also have to choose a value for g (gravitational acceleration).

Re:Ben Franklin & precision

[thegarbz]

Wouldn't the length of a swing of a pendulum vary depending on gravity? This also varies depending on where on the planet you currently are.

Re:Ben Franklin & precision

[Anonymous Coward]

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.

Both of these are variable. The period of your pendulum depends on the local strength of gravity - it will depend on where you are on the Earth, and on your altitude. The solar day varies too, depending on the time of year (from slight changes in the distance from the Earth to the Sun) and from tidal interactions with the Moon.

Re:Ben Franklin & precision

[Anonymous Coward]

and this pendulum's period is affected by variatons in gravity?

Re:Ben Franklin & precision

[Anonymous Coward]

The pendulum metre (the length of the arm of a pendulum with a half-period of one second) was supported mainly by Condorcet and Tallyrand. It had two problems: reproducibility and unit dependence.

The first was a practical problem, since the period of a pendulum is principally latitude dependent; drag and compressibility of the medium through which the pendulum moves; and variability rooted in what these days we would call the local gravitational potential gradient, which depends on (among other things) altitude and orientation.

Nineteenth century length standards based on pendulums required the measurement to be taken in vacuum at a particular latitude, meridian, temperature, and altitude; it also required a practical and non-circular definition of a second (Kater's mean solar second pendulum was a popular frequency standard that arose later, and was at the time known to have errors introduced by the Earth; eighteenth century pendulum frequency standards were noticeably less reliable).

The unit dependence objection was that the second as a unit was still somewhat ill-defined (it was easier to use a pendulum of a known length and at a fixed location to track the mean solar second than to synthesize a second) and the non-decimalized nature of the second was still a matter under discussion -- there were concrete proposals to use a different interval as the fundamental unit of time without regard to the second's use (or replacement) in civil time. Since it was still possible that the second might be replaced eventually, defining a metre based on a pendulum with a half-period of one second was unappealing.

The second was not replaced, although reproducibility of the 10^-7 pole-to-equator measurement posed unexpected problems in practice.

The eventual light-second approach is much more reproducible and has been gaining precision as frequency standards and interferometry improve.

not very simple

[Anonymous Coward]

maybe if you take out any isotopes of oxygen and hydrogen. the other issue is that temperature is a bit tricky to measure precisely, it's really a measure of the average movement of the molecules. it might be easier to just adjust for the loss of the 130 year lump of metal than measure water accurately.

Re:not very simple

[asher09]

temperature is a bit tricky to measure precisely, it's really a measure of the average movement of the molecules.

It is very easy to measure the temperature VERY accurately. For instance, you can buy this low-end thermometer https://www.vwrsp.com/catalog/product/index.cgi?catalog_number=61220-670&inE=1&highlight=61220-670

maybe if you take out any isotopes of oxygen and hydrogen.

Please review your chemistry textbook! The molecular weight takes into account the percentage of other isotopes that occur naturally for each element. So need to "take out any isotopes".

Exactly how do you stop time to get an accurate...

[Danathar]

As a believer in Zen I object to the whole philosophical idea that a Kilogram can in any way be real. :)

But....Zen would teach that it's still useful.

My Proposition

[Anonymous Coward]

If only we could find some substance of which a round numbered amount would contain a mass of exactly 1 kilogram. Ideally, this substance would be easy to find and measure.

story from the 90s

[cinnamon colbert]

so the entire world's system of weights depends on this block of Pt-Ir in paris Every now and then, they have to take it out of its sealed container, flushed with ultrapure He, and actually use it to verify a secondary std trouble is, you have to clean it. apparently, there is one old guy who is the only person in the world who can clean the Pt Ir cylinder without changing its weight by more then a few micrograms So....there is a scientific conference, what do we do when this guy retires ?

There are two problems:

[Anonymous Coward]

1) The kilogram (or any other mass unit) is hard to standardize and now we have to search for another reference, better than a metal cylinder (or any other object) -- because this sucks;

2) Another thing is to object the unit itself; we been thru this and, to be blunt, the only country not using the kilogram is the US (Liberia and Myanmar can change in a snap, if they want). Good thing I'm not from the US.

But we don't use the kilogram!!!

[richardkelleher]

In the US we still don't do metric, either we are too good for it or too stupid to figure it out. Who can say? That said, what right do we have to join in this debate?

Re:But we don't use the kilogram!!!

[shutdown -p now]

You do use the kilogram (and metre) even if you do not know it - your units of measurement are defined in terms of SI units by your standard bodies. 1 yard is exactly equal to 0.9144 meters. 1 pound is exactly equal to 0.45359237 kilograms. As such, the correct definition of kilogram affects pound as well.

Re:But we don't use the kilogram!!!

[richardkelleher]

I was of course being sarcastic. I would like to point out that, as I heard in a physics class some place about 30 years ago, that while a pound is a unit of weight, a kilogram is a unit of mass and thus only have this relationship in earth gravity.

Re:But we don't use the kilogram!!!

[shutdown -p now]

pound is a unit of weight

Admittedly I'm not an American, nor a native English speaker, but I thought that unqualified "pound" can refer to either mass or force (weight being force) depending on the context, and when clarity is needed, pound-mass and pound-force are used instead.

Re:But we don't use the kilogram!!!

[donscarletti]

In my country of birth Australia, we used Imperial units until the 60s and 70s, when we switched, right after we adopted decimal currency ($1 = 100c, not 1£ = 20d = 240p). In reality, it was quite a pain in the arse at the time, but the inconvenience faded in a few years and we were left with a better system of measurements in the long run. If a country expects a bright future of growth and progress, then accepting a few years of mildly reduced productivity in exchange for long term benefits makes good sense. Australia was a bit of a backwater at the time that system was adopted, but grew sharply in the decades after, not cause and effect in any way shape or form, but still a positive step.

Let's use some calculus

[tepples]

We're talking about something that needs to be accurate down to the microgram level.

Even if it's circular, one can still take the limit as the pressure converges to STP, right?

That was almost a haiku

[tepples]

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

Re:That was almost a haiku

[cynyr]

I thought Haiku's needed a seasonal reference and an expletive, counting "frelling" you still need a season in there...

http://en.wikipedia.org/wiki/Haiku

Not so fast bucko

[tepples]

Computers use base 2, humans use base 10.

Not so fast. Babylonian uses base 60, Chumashan uses base 4, Basque and Welsh use base 20, Gumatj uses base 5, Chepang uses base 12, and Yuki uses base 8.

wtf

[pinkeen]

Don't they have more important things to investigate? I mean millions (billions?) of people use this measure everyday and it's fine. US government is the last body to have any say in this matter. I mean don't you people use imperial units? Just stick to it and leave our measures alone...

The solution

[Anonymous Coward]

Everything should be able to be converted to a measure of gigaquads.

Thanks, but no thanks.

[Tanuki64]

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.

sure you can.

[swschrad]

declare the kilogram to be the equivalent of N number of electron volts, when converted to mass. ... and the crowd goes wild...

e = mc^2

[dskoll]

Mass is just energy in another guise, so if we could come up with a reliable energy standard (eg, the quantum of energy released when an electron jumps from state A to state B in a given atom), we could define a kilogram in terms of (many) quanta of energy.

I don't know how useful that is practically, though.

I agree

[Anonymous Coward]

Lets get rid of the kilogram. More Americans refer to weight OR volume by "shitload" anyways. I am sure there is some correlation between eating at Taco Bell and defining a standard unit of weight as 1 SL.

The greatest of Heists!

[The_mad_linguist]

More importantly, the standard kilogram has recently been stolen.

Seriously?

[EricX2]

Did the slashdot editor think it would be fun to have another Anti-American flamewar or something? I'm from the US, I don't object to the kilogram. There have been no protests, no elections asking to ban, or commercials asking for people to write to their congress to get rid of the kilogram.

The story should read as follows:
Physicists believe the physical kilogram located in a vault in France may not have the same mass as it once did before and the NIST in the United States agree that it should be measured with differently.

I want to suggest a future article:
US Objects to calling Soccer Football.
US Objects to the word litre.
US Objects to using GMT as the universal time, wishes to change to EST.

Those will get the Anti-American crowd going. It's a surprisingly large group on a web site hosted in the United States, and founded by an American.

How about this:
US Objects to Anti-American posts on American web sites? What is the big European nerd news site, I want to go complain about people I don't know anything about!

It's a plot...

[gstrickler]

Ok, let's start with the obvious. sarcasm - Since I'm in the USA, What's a Kilogram? Now on to some paranoia. The real purpose of this is so they can gradually devalue the kg as necessary. They took us off the gold standard in 1963/1964, and all the other SI units are based upon things an average person can't measure or compare, so if they eliminate the physical kg reference cylinders, then they can gradually change the "standard" at will and we'll all get lighter (or heavier) and an ounce of gold won't be the same. /sarcasm

Of course, as someone who (deludes himself into thinking he) knows something about science, I'm completely in favor of defining a kg upon something that won't vary (even a trivial amount) over time. As such, this is a good plan.

As a bonus, it frees up 36kg of platinum and 4kg of iridium, both of which are in short supply. Which brings up one final question, how much can the US get by selling 1.8kg of platinum and .2kg of iridium?

The Silicon sphere?

[strangluv2]

I thought we had this resolved, or coming close to it: http://www.theage.com.au/news/national/making-an-exact-difference/2007/06/14/1181414466901.html

Ever tried weighing water?

[Nicolas MONNET]

At ambient temperature & pressure? You can't, you can only measure its weight plus that of its container.

Also it evaporates.

Oooold news is oooold

[RichiH]

We have known for ages that the meter, the kilogram etc changed over time. That is why they replaced or are in the process of replacing the reference physical bodies with exact measurements. Google around for it. The lengths those people are going to are simply mind-boggling and truly inspiring. These people take their work _seriously_.

idea

[null8]

Cant' one define a Kilogram from E=mc^2? take some value for energy, c is a constant, and a kilogram can be defined as a fraction of m.

Re:It's not the mass, it's that it's not decimal..

[pommiekiwifruit]

A short ton, a long ton, a metric ton? Heck, the US has about three different sizes of gallons (one for grain, one for water, one for oil) and two different lengths of land miles (survey mile and statute mile) and hence feet/inches/rods/chains/furlongs etc. You may well remember that there are 80 chains to a mile, but is that a survey mile or a statute mile? Sheesh, even your border with Canada is not even accurate.

Re:It's not the mass, it's that it's not decimal..

[pommiekiwifruit]

Also they vary from country to country. So a pint is a different number of ounces depending on where you are, and there are several different types of ton. Personally I think it is 1000kg (New Zealand), not 2240 pounds (UK before 1985) or 2000 pounds (Canada) :-)

Re:It's not the mass, it's that it's not decimal..

[cynyr]

you missed, inches in a feet, feet in a yard, and yards in a mile, lbs in a bushel.

On a similar vein

[tekiegreg]

Anyone know how the liter is doing or the meter? I imagine the liter has had some evaporation or leakage issues and the meter is probably suffering a similar fate as the kilogram (it's measuring stick ends deteriorating).

Re:On a similar vein

[Chirs]

Both the liter and meter have standard non-physical-object-based definitions. For example, the meter is "the distance covered by a beam of light in a vacuum in a specific amount of time", where the amount of time is given by an atomic clock of some sort. (Used to be vibrations of a specific cesium atom, but I think that's changed now.)

The kilogram is the only remaining fundamental unit that is based on a physical object.

I'm American

[Anonymous Coward]

Uhm, I'm 'merican and WTF is a kilogram? Is it like, a pound?

Chuck Norris

[DarthVain]

His weight would never degrade, and if Quantum Physics ever tried to mess with him, I'm pretty sure it would get a round house kick.

While we're at it

[ekc]

Could someone explain to me why people always speak of the kilogram as the standard unit of mass and not the gram?

native oxide layer

[Anonymous Coward]

I'm sure the researchers have taken it into account but what about the formation silicon dioxide on the surface of the silicon sphere? I'm surprised no one has asked about it here.
Won't that affect the result? I guess it must be few enough Angstroms thick that it doesn't matter, and/or that its growth is self-limiting and it would be a known thickness.
Posting AC since I already modded in this thread.

Re:It's not the mass, it's that it's not decimal..

[rec9140]

"ounces in a pound"

16lbs

"how many pounds in a hundredweight"

112lbs

"how many pounds in a ton?"

2000lbs to the ton.

" None of those numbers ends in zero...all are a pain to convert."

Your lax educational system which can not offer the math skills needed to convert from various weights and measures is not a problem that needs resolved via a new system.