Kilogram Conflict Resolved At Last (nature.com)

An anonymous reader writes: As the capabilities of science and engineering expand, they rely more on the precision of measurements. It's vitally important, then, to make sure the standard units underpinning those measurements don't change. This is a problem for the kilogram. For years, it has remained the only SI unit based on a physical object — a small cylinder of platinum and iridium. Scientists have been arguing about how to replace it for decades, but now it looks like their efforts are finally reaching fruition. They finally have all the data they need to define the kilogram with mathematical constants, which solves the problem of the variability of physical objects. "One method, pioneered by an international team known as the Avogadro Project, involves counting the atoms in two silicon-28 spheres that each weigh the same as the reference kilogram. This allows them to calculate a value for Avogadro's constant, which the researchers convert into a value for Planck's constant. Another method uses a device called a watt balance to produce a value for Planck's constant by weighing a test mass calibrated according to the reference kilogram against an eletromagnetic force." Further research has narrowed down the value of Planck's constant, and experimental data from standards bodies is finally matching up. "If they are proved right, in 2018, Le Grand K will join the meter as a museum piece."

Comments

A weight has been lifted.

[truck_soccer]

I'm sorry.

Re:A weight has been lifted.

[JustAnotherOldGuy]

I support the metric system every inch of the way.

Re:A weight has been lifted.

[fyngyrz]

Personally, I measure everything using chi, bu, and li. It's easier to convert from myriad and avoirdupois quartiers that way.

It all goes to hell when I'm baking, though. :)

Re:A weight has been lifted.

[JustAnotherOldGuy]

Personally, I measure everything using chi, bu, and li. It's easier to convert from myriad and avoirdupois quartiers that way.

It all goes to hell when I'm baking, though. :)

Heh, I once printed out a recipe for my girlfriend that listed all the ingredients in micro-grams.

"120 million micro-grams of flour"
"56 million micro-grams of Nestles chocolate drops"

She never did bake that cake for me. :(

Re:A weight has been lifted.

[Toshito]

I support the metric system every inch of the way.

You've just put your foot in your mouth

Re:A weight has been lifted.

[david_thornley]

Damn punsters. Get off my yard!

Re:A weight has been lifted.

[Anonymous Coward]

Their research has reached critical mass.

Re:A weight has been lifted.

[Vainglorious Coward]

It's ok, they won't be here furlong

Re:A weight has been lifted.

[Darinbob]

Very naughty, a spanking is in order. Bring out the yardstick.

Re:A weight has been lifted.

[KGIII]

You know, 2/3rds of 'pun' is "p-u." (Best said aloud.)

Re:A weight has been lifted.

[diakka]

Probably because you were using stolen trade secrets for your recipe.

Re:A weight has been lifted.

[Anonymous Coward]

Actually the weight units in the imperial system are based on fractions of a kilogram. It's the only group of units that still does this.

Source: https://www.youtube.com/watch?v=ZMByI4s-D-Y

Re:A weight has been lifted.

[Methadras]

Give them an inch and they'll take a Km.

Don't you mean accuracy of measurement?

[Anonymous Coward]

Let the debate begin!

Re: Don't you mean accuracy of measurement?

[Anonymous Coward]

No. Accuracy implies a reference, but in this case, people are trying to define the reference; hopefully, there definition will be precise.

Re: Don't you mean accuracy of measurement?

[Anonymous Coward]

No. Accuracy implies a reference, but in this case, people are trying to define the reference; hopefully, there definition will be precise.

It will be precise.

By definition.

Re: Don't you mean accuracy of measurement?

[Anonymous Coward]

More precise than your understanding of there and their, hopefully.

Re:Can the "Paid Posts" go to the museum too?

[truck_soccer]

Aren't the red ones fresh out of the fire hose? I don't know how to slashdot.

are we still in the quagmire?

[AndyKron]

Does this mean the US can now join the rest of the metric world, or are we still in the quagmire?

Re: are we still in the quagmire?

[Chris Mattern]

Does this mean the US can now join the rest of the metric world, or are we still in the quagmire?

Giggity giggity...

Re: are we still in the quagmire?

[armanox]

In all honesty, why would the American people want to change?

Re: are we still in the quagmire?

[Anonymous Coward]

We in the US cannot accept this as settled until we have a way to calibrate our scales based on something that is physical. It is all fine to babble about Silicon atoms and Avocados and the like, but we need something to put onto a balance scale for calibration. I've seen avocados and they aren't constant. And Silicon gets smaller every year - why, they were recently saying that chips are going to 9 nano-whatevers or some such.

Re: are we still in the quagmire?

[Anonymous Coward]

Because elitist and ignorant Europeans are too stupid to understand how to use Imperial measures.

I've lived in countries where both systems are used and the SI does nothing useful outside the areas of science and technology. For daily living, I never found a case where I was missing metric measures or where metric measures were making things easier.

Most of the time it was a draw and the rest of the time the Imperial measures wound up being better.

Re: are we still in the quagmire?

[Anonymous Coward]

The US system of measurement (1) and the metric system approach the problem from two completely different viewpoints.

In the US system the goal is to make dealing with the physical objects easy -- to get from one size to the next larger one most of the time you double something. To get to one size to the next smaller one most of the time you halve it. Mathematically this makes things a bit tougher when doing calculations. The naming system unfortunately requires you to remember different names for each unit.

In the metric systems the goal is to make the mathematics easy (and also the naming system). In this system to go from one size to the next you simply shift where the decimal point is located. However, dealing with the physical objects is actually much tougher. To go from one meter to one centimeter you need to cut the length into 100 equally sized pieces...this is hard!

(1) It turns out that both systems were originally French...the original name of the US system is the avoir du pois system (goods by weight).

Re: are we still in the quagmire?

[Opportunist]

So the next joint-venture probe doesn't crash?

Re: are we still in the quagmire?

[Opportunist]

Judging by some women I know, silicon actually gets larger every year.

Re: are we still in the quagmire?

[jittles]

In all honesty, why would the American people want to change?

How about for no other reason than to realign our measurements with the rest of the world? NASA has a document with a few incidents that were caused by using the incorrect units.

Re: are we still in the quagmire?

[Anonymous Coward]

Because elitist and ignorant Europeans are too stupid to understand how to use Imperial measures.

As an elitist European I probably know how to use imperial measurements way better than you do.
At least I understand that imperial units are localized, meaning that a German inch is of a different length than a British inch.
We all had imperial units once upon a time, but it caused so many issues that it was better to just change to a common system.

Re: are we still in the quagmire?

[Anonymous Coward]

Actually, in machining the argument can be made that the Imperial system is better, thousandths fit common tolerances much better than microns. What needs to die are fractions of an inch, if I'm working at that scale and tolerances metric is much easier. Half of 27 & 19/32nds? Fuck that noise.

Re: are we still in the quagmire?

[phantomfive]

Scientists at NASA already use metric. They have been for decades.
People in the USA who want to use metric generally use it.

Re: are we still in the quagmire?

[bobbied]

Does this mean the US can now join the rest of the metric world, or are we still in the quagmire?

What? Look I LIKE having two set's of tools when I'm working on my cars... SAE/Metric Rules!

Can you imagine how many tool makers would suffer if we stop using SAE? PLEASE, there is no way they will let this happen...

(/sarcasm)

Re: are we still in the quagmire?

[Anonymous Coward]

Other countries use a casual mix of metric and non-metric. Canadians often use inches for height, and time (!) for distance; people in the UK use stone for weight; etc...

Re: are we still in the quagmire?

[turbidostato]

"In the US system the goal is to make dealing with the physical objects easy -- to get from one size to the next larger one most of the time you double something."

I get it, I get it!

So that explains why a foot is two inches, a yard two feet, a mile two yards and, then, two fluid ounces make a cup, two pints a quart and two quarts a gallon.

How cute, isnt' it?

"To go from one meter to one centimeter you need to cut the length into 100 equally sized pieces...this is hard!"

Yeah, well, and to go from a mile to a foot you need to cut the lenght by... how many it was, again? 5.800? Now, that certainly seems so much easy.

Re: are we still in the quagmire?

[jbengt]

In the US system the goal is to make dealing with the physical objects easy -- to get from one size to the next larger one most of the time you double something.

If that were true, it'd be nice. But, no, I have to figure fractions of inches, 12 inches to the foot, 3 feet to the yard, and 1760 yards to the mile. Not to mention that the US survey foot is different than the standard foot in some states and not in others. And pressures get measured in pounds per square foot, pounds per square inch, feet of water, inches of water, inches of mercury, atmospheres, etc., none of which relate by multiples of two. And a gallon is the volume of a cylinder 6 inches high by 7 inches in diameter if you assume pi to be exactly 22/7 - no factors of 2 between cubic feet and gallons. Don't even get me started about viscosity, where we have wonderful measures like Saybolt Seconds Universal, which doesn't even relate linearly to the standard measures that you need if you're doing any calculations. (ASTM had to issue a standard - ASTM-D-2161 - for converting between useful measures of viscosity and SSU or SFU in order to minimize discrepancies between measures.)

In the metric systems the goal is to make the mathematics easy (and also the naming system).

The good thing about SI units is that they're mostly consistent. No need to convert pounds to slugs and miles per hour to feet per second before plugging the numbers into the formula. Fundamental measures relate directly to derived quantities.

Re: are we still in the quagmire?

[Anonymous Coward]

i have documents about the millions killed by the meter proponents.

but yeah, meter helps to build guillotines abnd nice gulags.

Re: are we still in the quagmire?

[Anonymous Coward]

so the silicon mass reference feminizes science ? no male truths anymore ?

thats great for the progressive future and i want this with some vodka tsheka.

Re: are we still in the quagmire?

[ericloewe]

Too bad the aerospace contractor didn't use SI units.

Re: are we still in the quagmire?

[argStyopa]

You're using a story about the metric system's attachment to an utterly arbitrary unit of measure as the spot you're going to stand and shake your finger at the Imperial system? The metric system is JUST as arbitrary.

And if you're going to go with the "well everyone else uses it, let's stop confusing the system" then I'd suggest we also work on getting rid of all those pesky foreign languages and make everyone speak English, for precisely the same reason.

Re: are we still in the quagmire?

[Darinbob]

The irony is that the (US) National Bureau of Standards is involved with helping this effort to define the Kilogram.

Re: are we still in the quagmire?

[Anonymous Coward]

A mile is far more than 5.8 feet.


stupid eurotrash using a decimal as a thousands separator

Re: are we still in the quagmire?

[Darinbob]

They can use them, if they bother to think. However they prefer to laugh at Americans. I have seen Australians living in the US for decades who will express mock surprise every time they see something measured in quarts or ounces. The joke gets old...

Re: are we still in the quagmire?

[Darinbob]

It's a non-issue. Those sorts of mistakes continue to happen even if using the same measurement systems, because the real problem was failing to double check the numbers and use proper testing. Everyone in the US involved in science or technology already uses metric anyway. We're generally smart enough to handle two measurement systems at the same time.

Actually I think a lot of physics students of a certain age do better than those who only used metric, because there were lots of word problems in college involving the conversion from one quantity to another. Foot pounds per fortnight, that sort of thing. If you can handle those problems then doing it in metric is a cinch.

Re: are we still in the quagmire?

[Darinbob]

Those incidents were caused by lack of testing and verification. There should be no difference between getting a part sized incorrectly in feet versus a part sized incorrectly in meters, if you don't double check that it fits properly then you increase chances of failure. If you make astronomical calculcations then you need to verify them regardless of what units are used. If you bring together two complicated pieces of machinery designed by two groups who don't talk to each other then you need to validate them.

The use of metric would not have removed the cause of these incidents, though it might have masked some of the problems for a bit longer. If you're going to screw up because someone assumed meters when it was feet, then you will also screw up if someone assumes grams instead of micrograms. You should always pay attention to the units!

Re: are we still in the quagmire?

[Darinbob]

The mathematics with metric only gets slightly easier. The fundamental math remains the same though. The metric system helps out students mostly, or removes a simple conversion process that scientists have to know how to do anyway. It's not like the English system involves complicated mathematics but with metric everything is easy.

Today, a system based on powers of two makes much more sense. But the French revolutionaries who invented the metric system were used to counting on fingers. A system based on powers of ten has much more to do with human foibles and culture than with physical properties. They also wanted ten day weeks but that never took off; does that mean those countries who did not adopt the "simpler" calendars are backwards and stupid in the same way that they call Americans backwards and stupid?

Re: are we still in the quagmire?

[Anonymous Coward]

Here's a recent example I encountered.

Use a tape measure to find the square footage of a room. It's 12' 7 3/4" x 11' 4 1/2". How many square feet? I bet you need a calculator.

In metric, it's a far easier calculation.

Re: are we still in the quagmire?

[phantomfive]

They did

Re: are we still in the quagmire?

[jdschulteis]

The irony is that the (US) National Bureau of Standards is involved with helping this effort to define the Kilogram.

Not really ironic, because the US customary units are defined in terms of SI units, e.g. the pound is defined as exactly 0.45359237 kg.

Re: are we still in the quagmire?

[Darinbob]

Agreed, it's not ironic. But to many of those outside the US they find it strange because they think we're all backwards cave dwellers.

Re: are we still in the quagmire?

[KGIII]

We should have pointed that out during the whole freedom fries thing - we'd have converted the country to metric in an instant.

Anyhow, drugs have been teaching kids the metric system for years. 3.5g etc...

Re: are we still in the quagmire?

[Anonymous Coward]

"But to many of those outside the US they find it strange because they think we're all backwards cave dwellers" - incorrect because we know you're all backwards cave dwellers.

Re: are we still in the quagmire?

[rpstrong]

And you can multiply 3.85 x 3.47 in your head? My hat is off to you.

But if I was buying carpet, or figuring out paint coverage, I'd just go with 144 square feet and call it a day.

And therein lies the advantage of Imperial units. They evolved into units which are useful in everyday tasks. Metric may be fine for scientific work, but for real world measuring, I'll stick to Imperial.

Re: are we still in the quagmire?

[rpstrong]

Canadians often use inches for height, and time (!) for distance

I moved to Los Angeles county many years ago, and noticed that people out here would also typically express driving distance in time, not miles. This was especially true for trips involving freeways.

Re: are we still in the quagmire?

[rpstrong]

The standard "male truth" usually involves a fictitious eight inch measurement.

Re: are we still in the quagmire?

[rpstrong]

So that explains why a foot is two inches, a yard two feet, a mile two yards and, then, two fluid ounces make a cup, two pints a quart and two quarts a gallon.

Forget about doubling - try taking a half, or a third, or a quarter, or a sixth, or a twelfth of a foot - each resolves to convenient, integral measurements [IOW 6, 4, 3, 2, or 1 inch(es)]. And take the humble cup, so often used in cooking. 32 ounces, neatly capable of being successively halved down, to the down to the ounce level.

Perhaps that's the prime advantage of the Imperial system - the measurements evolved from units which were actually used for measuring things, not a system where the units are arbitrarily defined.

Re: are we still in the quagmire?

[rpstrong]

The examples you give mostly relate more to the scientific and tech world, but are of little interest to a carpenter, a cook, or a driver - who are more interested in everyday measurements.

Re: are we still in the quagmire?

[ericloewe]

From https://en.wikipedia.org/wiki/... (emphasis mine)

The Mars Climate Orbiter (formerly the Mars Surveyor '98 Orbiter) was a 338 kilogram (750 lb) robotic space probe launched by NASA on December 11, 1998 to study the Martian climate, atmosphere, and surface changes and to act as the communications relay in the Mars Surveyor '98 program for Mars Polar Lander. However, on September 23, 1999, communication with the spacecraft was lost as the spacecraft went into orbital insertion, due to ground-based computer software which produced output in non-SI units of pound-seconds (lbf s) instead of the metric units of newton-seconds (N s) specified in the contract between NASA and Lockheed. The spacecraft encountered Mars on a trajectory that brought it too close to the planet, causing it to pass through the upper atmosphere and disintegrate.

So, as you see, the idiots at Lockheed were so attached to their stupid imperial units that they got the software wrong.

Re: are we still in the quagmire?

[phantomfive]

Oh, yep, looks like you're right. Somehow along the way I had gotten the idea that the Europeans had incorrectly converted it to Imperial because they thought that is what NASA expected.

Re: are we still in the quagmire?

[turbidostato]

"not a system where the units are arbitrarily defined."

Yes: surely a pint is a pint and a mile is a mile, nothing arbitrary there!

But then, there's the minor problem about explaining why a British pint is 568 ml while the US pint is only 551 ml. Oh, wait! that's the *dry* pint, because, as everybody knows, the *liquid* pint is a mere 473 ml.

But those are volumes; distances surely will be much better: like a mile, everybody knows its 1609,34 meters. Well... everybody but seamen and pilots: they naively think a mile's proper and non-arbitrary length must be 1852 meters.

No, they really are not arbitrary units.

And now, please make yourself a favour and look for Asimov's essay "Forget It!"

Re: are we still in the quagmire?

[rpstrong]

"not a system where the units are arbitrarily defined."

Yes: surely a pint is a pint and a mile is a mile, nothing arbitrary there!

But then, there's the minor problem about explaining why a British pint is 568 ml while the US pint is only 551 ml. Oh, wait! that's the *dry* pint, because, as everybody knows, the *liquid* pint is a mere 473 ml.

I'm not concerned about fairly trivial differences in how "pint" is defined. Of more interest is that a pint of beer on any of those scales is a convenient amount to hold and drink. And in any of those scales, there are still two pints to a quart, four quarts to a gallon - that convenient doubling scale.

But those are volumes; distances surely will be much better: like a mile, everybody knows its 1609,34 meters. Well... everybody but seamen and pilots: they naively think a mile's proper and non-arbitrary length must be 1852 meters.

No, they really are not arbitrary units.

No, nothing arbitrary there. I don't know offhand how the statue mile evolved; I'll leave that as an exercise for the student. But the nautical mile is of more interest, as it was created as an aid to navigation. It was defined as the length of one minute of altitude, as measured along a north-south meridian. Arbitrary? Certainly not.

Looking back at your response, it would seem that your beef about SI units is that the disparity in using the same (or nearly same) name for different amounts in different locations or contexts. For me, that is not an issue. If my speedometer reads 75, I know that it is statue miles per hour, not knots. If a recipe calls dor a cup of milk, I know that a pint will be double what I need. Why should it bother me that pints are different across the pond?

And now, please make yourself a favour and look for Asimov's essay "Forget It!"

Read it, mildly interesting.

The kilogram is based on a chunk of metal?

[I'm New Around Here]

The metric zealots get mad at me for pointing out the points of weakness of the metric system. Here is one I forgot about. Their length unit is based on a physical cylinder of metal. Although it makes sense, since the original design spec apparently was "Make it a little longer than a yard, just to piss of those English bastards."

Re:The kilogram is based on a chunk of metal?

[ColdWetDog]

You're not going to win this one. From the nice Wikipedia article concerning the definition of a foot:

Since 1959, both units have been defined by international agreement as equivalent to 0.3048 meters exactly. In both systems, the foot comprises 12 inches and three feet compose a yard.

It's cylinders all the way down.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Kilogram=mass, not length.

The Metre is defined by the speed of light, and atomic clock timings.

Re:The kilogram is based on a chunk of metal?

[Maritz]

The metric zealots get mad at me for pointing out the points of weakness of the metric system. Here is one I forgot about. Their length unit is based on a physical cylinder of metal. Although it makes sense, since the original design spec apparently was "Make it a little longer than a yard, just to piss of those English bastards."

Perhaps your memory is failing you again..? A metre is defined as the distance light travels in 1/299792458 of a second. Originally, I believe in the 18th century, this was intended to be one ten-millionth of the distance from the pole to the equator. The former is obviously a better definition because Earth is not perfectly spherical.

In any case... Using the term 'metric zealot', apparently un-ironically, right out of the gate - doesn't do your credibility any favours (or it's a deliberate troll; in which case - well done).

If you're a genuine 'imperial zealot' then what, out of interest, is your best pro-imperial argument? I'm curious because as far as I can tell, imperial is shit. And I say that as someone who has had to deal with both systems.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Care to enlighten us about the weaknesses of the metric system? Because I quite like the fact that I know exactly how many cm there are in 2 km. Can you quickly tell me how many inches are there in 1.3 miles?

Also, yes, everyone is aware of the physical basis for the kg. What about your pound? Is it based on something the "metric-ers" haven't found yet? Oh wait, it's based on the kg...

Re:The kilogram is based on a chunk of metal?

[AmiMoJo]

Their length unit is based on a physical cylinder of metal.

Nope, it's based on the speed of light in a vacuum. You are thinking of the unit of weight.

Anyway, how is that stupid? The imperial version, the pound, is based on a physical quantity as well because it is officially defined as 0.45359237kg. In fact most (all?) imperial measures are defined as precise metric values now, so any criticism you have of metric standards apply equally to imperial ones.

Metric is far superior. You get easy decimal maths, easy conversions, SI units of magnitude and naming conventions. If you want to use base 12 for the nice divisions, you can use base 12. The only reason to stick with imperial measures is familiarity and legacy stuff.

Re:The kilogram is based on a chunk of metal?

[Sique]

This is plainly wrong. The original definition of the metre was "the 10,000,000st of the distance between Northpole and Equator", because this was the closest one could think of to have it about a yard long. Later, better measurements have shown that the prototype built to represent this distance was about 0.2 millimeters short, thus the actual distance between Northpole and Equator is about 10,002 kilometres.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Well the full story of the meter is:
1. let's make something around 1 yard in length based on the Earth
2. choose one ten-millionth of the distance from the pole to the equator
3. define as the distance between two marks on a chunk of metal
4. define as the distance light travels in 1/299792458 of a second

He brought up 1 and 3. You brought up 2 and 4 but that doesn't mean he's wrong. All 4 points are correct.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Never had to know how many inches are in 1.3 miles. So?

But anyways all I have to do is google "how many inches in 1.3 miles." The answer is 82368. Took me about 25 seconds to get that answer.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Aren't you confusing grams with meters?

Source of meter though was not based on 'pissing of the English', but it was set to be "110,000,000 part of one half of a meridian". Mind that meridian 0 goes thru Greenwich, England :)

It's not the problem with how it came to be, but with the fact, that in metric system everything is base 10, and an imperial system is base WTF [1 land league = 3 miles = 24 furlongs = 240 chains = 5280 yards = 1540 feet = 190080 inches... oh and land league and sea league are different... ], and 'league' was based on a distance that average person could walk in an hour [damn, I can walk faster than that!]... and it's size varied from country to country... real smart...

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

It is now. It was originally based on the distance from the equator to the North Pole. You had precisely 10,000 KM from that and with 1,000 M in a KM, that gave you 10,000,000 M from the Equator to the North Pole. Like most measures they've redefined it so that it was more constant, but it was a completely arbitrary measure that makes no sense outside of science.

The meter is a rather awkward unit to use. It's too long for practical use in daily living and it's too short to be of much use otherwise. You can't divide it into useful lengths either. If you divide it into quarters which are a useful length, you're then stuck with all sorts of nasty fractions if you're actually using it. MM and CM are really too small for practical use.

It's really time to junk the SI for daily living and replace it with something that actually works.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Not that I'm defending the Imperial system in general, but 12 is a much nicer base than 10 because of all the divisors.

Re: The kilogram is based on a chunk of metal?

[Anonymous Coward]

Pish... I won't be happy until speed limits are posted in kilograms per furlong as they should be...

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Although it makes sense, since the original design spec apparently was "Make it a little longer than a yard, just to piss of those English bastards."

Unfortunately, the plan backfired when they started doing dick measuring contests.

Re:The kilogram is based on a chunk of metal?

[guruevi]

Length is based on light. Mass is based on this unit, before it was the weight of 1L water at sea level.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Indeed, as a USian, I must say that I don't much care for our units, I still don't actually remember the number of feet in a mile (5000 something?) and teaspoons/tablespoons, cups, quarts, gallons, they go up by 3x or 4x, I guess?

As an engineer, I am glad that at least electrical units were new enough that they didn't bother making imperial versions, I mean seriously, k, M, G, T, P, Y and m, u, n, p, f. Now I know how to convert all metric units that are in a single scale (eg mm to Tm is x10^15, Mg to mg is x10^-12), and there are fewer tricks to convert between disparate units in metric than with imperial (things like 1mL = 1 cm^3). I'm all for bringing the US in line with the simple system.

Re:The kilogram is based on a chunk of metal?

[camperdave]

It goes back further than that. The Mendenhall Order switched the US from having physical reference artifacts for the yard and pound to basing them on the metre and kilogram way back in 1893. The US has been officially metric behind the scenes for 122 years.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Why would I want to know how many centimeters there are in a kilometer or how many inches there are in a mile? Knowing how many feet are in a yard or how many inches are in a foot are actually useful. Knowing how many yards or inches they are in a mile is pointless masturbation. People don't generally bother because it's a waste of time to know.

If you folks in Metric-land are regularly thinking about how many CM there are in a KM, then you're doing something horribly wrong. With the exception of physics and some other niche applications, you're not going to have tools that are precise enough to worry about centimeters and kilometers at the same time. Even the laser based survey equipment isn't that precise.

Measurements aren't typically precise enough to worry about inches when you're talking about miles. If you are in that situation, then you're going to just use decimals anyways. All odometers in the US are decimal based, the base units are miles and tenths of miles.

As far as the pound being based on the KG, I'm not sure how that bolsters the metric side of the argument. It has to be based on something. Previously there were official standards that had to be met, now we base them relative to a KG. The issue with the SI isn't that there are standards based upon constants, it's that the units are fucking stupid for non-scientific use.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Try living with Imperial measures for a while and you'll realize what a revelation it is. SI is superior for things that nobody does and inferior for the things that people actually do.

I hear this bullshit over and over again about how easy decimal math and the conversions are. The only problem is that nobody actually does those things. I rarely, if ever, need to convert units in Imperial measures. Occasionally, I'll have to convert cups into Tablespoons or vice versa, but that's not something that I have to do very often.

It's sort of ironic that the people boosting the SI are mostly people whose math skills suck. Imperial measures are set up so that you don't have to do a lot of converting.

Re:The kilogram is based on a chunk of metal?

[pla]

what, out of interest, is your best pro-imperial argument?

Personally a fan of Metric, but Imperial does have one major thing going for it - Easy divisibility by low prime numbers.

In the modern world, almost no one "does" math anymore. We use a computer or a calculator, and just get the answer. Shifting up or down by powers of ten makes for convenient readability, but otherwise doesn't matter in the least. Computers would actually work better if we switched to all binary, and wouldn't work any worse if we still used Imperial.

For most of human history, however, having units of measurement easily divisible into 2/3/4/5/6/8/9/10/12/etc parts meant that your average math-illiterate farmer or carpenter could still successfully figure out how to use a pair of oxen to spread four bushels of seed over a virgate (with a peck left over), or five cords of wood into 128 days of winter, and so on. No one cared about the weight of supper in terms of the speed of light in a vacuum, they cared about having enough to heat and eat through the winter.

Re:The kilogram is based on a chunk of metal?

[PPalmgren]

Honestly, if you want to understand why imperial is around, I think the best example is the AU. 1 AU = distance from earth to the sun, a completely arbitrary number that doesn't fit exactly on any base-10 or base-12 unit scale but serves as a frame of reference while measuring things of similar nature. Measuring something in AU in space does nothing different than measuring it in km or m would, but seeing something represented in AU allows us to approximate references much easier.

What I'm getting at is that imperial has inertia as many people have been using it as their reference, or language of measurement, for everyday life. When someone tells them something in meters, like a second language, they translate it mentally to feet or km to miles to get mental perspective. This is easy for a lot of people on this site, but not so for the common mathematically challenged. The people who need standard measurements still have the option to use them and are typically the more intelligent of the bunch, so there's little benefit to forcing everyone else to change.

In the end, measurement systems are just a language. Forcing imperial out would be like forcing English as the only language in Europe. When you frame it that way, its easier to understand why there's so much resistance.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

" You can't divide it into useful lengths either."

You're being an obtuse cunt and you know it.

1/2 x 1m = a half meter
1/5 x 1m = one fifth of a meter
1/100 x 1m = one hundreth of a meter, which is also called a centimeter

It gets even easier for other powers of 10, see these.

Now, why doesn't anyone ever apply these useful and convenient prefixes to imperial units? They'd apply all the same. Nothing like going out for a kFoot jog around the block, or trying to find a 4 milliInch spanner. Oh wait, that's right, engineers do use thousands of an inch because it's useful.

Wake up idiots, being stupid does not deserve any rewards.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

"then you're going to just use decimals anyways"

Not sure what you learnt in school buddy, but you can use decimals any time you like for anything you want!!!!

Maths really is amazing isn't it.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

I always thought the Spec for the meter was. Lets make something up that makes our French cars seem much faster than they really are. So they naturally went for one thousand times a ten millionth of the distance between the north pole and the equator and called it the kilometer.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Try to convert people's weights in "stones" and pounds, to a purely pound-based number. Not fucking easy is it.

Re:The kilogram is based on a chunk of metal?

[I'm New Around Here]

Oh, my mistake. I read it as the length unit. Don't I look foolish.

Thanks for the correction.

Re:The kilogram is based on a chunk of metal?

[I'm New Around Here]

Yes, I misread the post. I saw kilograms and thought meters. Very bad mistake on my part.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

I can't remember the last time I had referred to leagues, furlongs, or chains...
Nor have I ever needed to to mix these and I strongly doubt anyone does this in metric either...

I don't say "San Fransisco is 120 miles, 230 feet, and 4 inches away, neither does anyone say "SF is 193.19121km away" or for that matter 193191.21 m

so which is better? 120 and a bit miles, or 193 and a bit km?

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

And 10 is a much nicer base than 12 because of all the multipliers...

Re:The kilogram is based on a chunk of metal?

[DarkTempes]

Celsius is just as arbitrary as Fahrenheit and both are base 10.

Kelvin is the only true logical temperature system given that 0 K is absolute zero but it might be impractical to use up to five digits for half (or quarter) degree increments on thermostats to handle the hundreds of degrees kelvin that room temperature is at.

Imperial is shit but metric isn't perfect either.

Re:The kilogram is based on a chunk of metal?

[slfnflctd]

Such an excellent description of how pragmatism wins out over abstraction purity throughout human history. There is still plenty of value to this.

I would argue, however, that if our species ever reaches anything resembling a 'post-singularity' state (and quite possibly well before then), the value of pragmatism will decline in all but the most esoteric matters.

Re:The kilogram is based on a chunk of metal?

[BadDreamer]

The (to me dubious) advantage of dividing by low primes pales utterly when you need to quickly calculate how much water you need in your dam to last through winter, or any other quick conversion between dimensions involving volume, area or anything else which is not in discrete units - and since you don't measure oxen or days in meters or kilos I fail to even see how your examples apply.

Plus, plug SI into Metric and quickly, in your head, with only moving zeros calculate how much energy is required to heat some water, from that how long it will take given a specific wattage, or how much a given volume of water weighs (and if you can recall its density, thus how much something else weighs) and from that how much force it will exert on the surface it sits on, and how hard it will hit an object if it falls a certain distance, or pretty much any other physics calculation - with no constants involved for moving in SI (except for material conversion, such as density).

It's simply astonishing how difficult such calculations are in Imperial, and how simple they are in Metric and SI.

Re:The kilogram is based on a chunk of metal?

[Maritz]

Thanks for that. I like to be generous about the best arguments for things even if I don't agree. On balance I still feel metric is much better, though I've seen plenty of convincing arguments that duodecimal/dozenal is a better go-to than decimal for similar reasons (divisible by 2, 3, 4 and 6 rather than just 2 and 5).

Re: The kilogram is based on a chunk of metal?

[Anonymous Coward]

In practice, "a bit under 200 km."

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

So, what you're saying is that you should use workarounds because you chose stupid lengths to begin with?

Nobody comes up with prefixes like that because we're not idiots. We know that prefixes like that exist in the metric system, they weren't brought into the system because they're not useful. Rarely do you need skip units. You don't need to know how many inches there are in a mile because measurements aren't that precise. You either deal with it as fractions of a mile or miles and feet. Throwing inches in rarely makes sense as the tools can't measure them anyways.

Yes, you can do that, but then you're left with an absolute mess. You wind up with these nasty fractions and decimals pretty much at the next step regardless of what you do. With Imperial measures, things are set up so that you're more likely to wind up with nice fractions including ones that you cannot do at all in metric. Good luck with 1/3 in metric, you can't do it.

Obviously, I'm the cunt, not the person that's going to great lengths to rationalize why a poorly designed system of measure struggles for what most people are using it for.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

This is a good argument. But in my opinion metric is not doing that bad of a job here. The idea is that you only have one unit per dimension (metre for length, gramme for mass, etc.) and you then use whatever basis you want. I don't see any problem in changing from base 10 to another and have 1/12 of a metre, 1/144, etc...

Re:The kilogram is based on a chunk of metal?

[AmiMoJo]

How is that not also an advantage for the metric system? If you want divisibility by low primes, just use multiples of 12 metric units. If you are going to use decimal inches anyway (because going to feet breaks your divisibility) you might as well just use decimal millimetres or centimetres in multiples of 12 "blocks". It even scales effortlessly.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

The point is that the "benefit" people have from the metric system is that it's base 10. The Imperial system as used in the US is base 10 when it's actually useful to be base 10 and not base 10 the rest of the time.

Hence why the metric system is never better than the Imperial system in daily living. We can express things using decimals, fractions or units and sub units as needed without having to get special tools to do it. Nobody is going to be confused if I say that something is 6.5' long. They may or may not convert that into 6'6", but they probably won't even bother. I could also express that at 6 1/2' as well.

Even in science a lot of the reason why SI is better is that the units were defined in that way. Apart from the primary units, all the others are defined with respect to those primary units of measure. The constants are mostly defined based upon them as well.

Re:The kilogram is based on a chunk of metal?

[Electricity Likes Me]

"People" don't do that.

Americans do that.

Countries with the metric system use metric as natural units because its what they're familiar with.

Re:The kilogram is based on a chunk of metal?

[tlhIngan]

Perhaps your memory is failing you again..? A metre is defined as the distance light travels in 1/299792458 of a second. Originally, I believe in the 18th century, this was intended to be one ten-millionth of the distance from the pole to the equator. The former is obviously a better definition because Earth is not perfectly spherical.

Through Paris.

The metre was officially defined as 1/10,000,000th the straight line distance between the North Pole and the Equator, through Paris, France.

It's why everything's in French (why the official term for "metric" is SI, or Systeme Internationale... French!).

Anyhow, the kilogram is the only unit of measure still based on a physical object, something they've been trying to change for decades now. The importance of this is if you can derive all the fundamental units of measure from physical constants, then it becomes a universal system of measurement.

And the reference kilogram has been losing weight, which means all of us have steadily started weighing more and more as time goes on.

Re:The kilogram is based on a chunk of metal?

[AmiMoJo]

It's not as bad as the UK. We use a mixture of both, and the division is mainly by age. Ask two people what a "mil" is, the younger (say under 40) will probably say "millimetre" and the older will probably say "thousandth of an inch".

Re:The kilogram is based on a chunk of metal?

[mr_mischief]

And the foot and inch in terms of meters... so...

Re:The kilogram is based on a chunk of metal?

[Opportunist]

Actually, the cm is a very handy unit. It's about the width of a finger (or thumb if you have slim fingers). You don't use fractions in the metric system. For good reason, it's base10 all the way down. For lengths/areas/volumes you usually use meters (for things like giving the area of your flat or the distance between two things that are nearby), centimeters (for things like the size of your TV or distances on your desk) and millimeters (for tiny things). And there is no need to work with fractions. Actually, it would be quite silly to use 1/3 meter, I have never seen or heard anyone use something like this. Because the meter has very convenient and easily convertible subdivisions. No need to start calculating. 1m 30cm is exactly 1.30 meters. Or 130cm if you prefer. Now please the same with 1 yard and 5 inches. No calculator allowed.

Re: The kilogram is based on a chunk of metal?

[Anonymous Coward]

I think you missed the point. People in France speak and think in French because that's what they're used to. Force them to adopt English as their national language and you'd have riots and pandemonium. Even if it held officially, people would use French over English anyway. That's what it's like for the common man to change their language of measurement.

Re:The kilogram is based on a chunk of metal?

[Bing Tsher E]

Not gonna happen. The singularity crap is this era's Fountain of Youth. The truth is, the more we learn, the more we discover how little we know.

Every generation nurtures this myth that they have everything almost figured out. Militaries employ brass bands for the same purpose- to boost morale and keep everybody working hard, cuz the boss wants a new, bigger yacht.

Re: The kilogram is based on a chunk of metal?

[Anonymous Coward]

Well, carpenters around the world seem to be able to use metric. Seems nicer than fractions of an inch.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

For that matter, 1/3 inch in 64ths, please.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Now do that in a forrest alone with not phone.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

That's why there is a nice, frequently needed, factor of 11, when you decompose the number of yards per mile.
Really nice and useful on a daily basis, an eleventh of a mile is exactly 160 yards. For the factors of 3, I could agree because of historical reasons, and they are convenient in time scales dividing the day in 3 shifts of 8 hours. But customary mathematical notation is in base 10, and is used for what is the most important thing all over the world these days: money so it won't change soon. (Well Britain switched to decimal money in the 60s, if you find documentation for the first releases of the PL/1 language in the early 60s, it had explicit support for pound subdivisions)

Re:The kilogram is based on a chunk of metal?

[Anonymous Cow Ward]

If you asked me what a "mil" is, I'd say a milliliter, but I use volume measurements more often than length.

Re:The kilogram is based on a chunk of metal?

[lars_stefan_axelsson]

Personally a fan of Metric, but Imperial does have one major thing going for it - Easy divisibility by low prime numbers.

And you've just realised why the standard kitchen module in the metric, i.e. European world, is 60cm wide... Much better than twelve...

Re:The kilogram is based on a chunk of metal?

[Sheldon_Cooper_1]

For that matter, 1/3 inch in 64ths, please.

21 1/3 64th, exactly. Now, 1/3 meter in millimeters, please? Most seem to think that the great thing about SI is that it is base ten. I disagree. The only thing special about base ten is that most of us have ten fingers.

Re:The kilogram is based on a chunk of metal?

[stasike]

No. Kilogram isn't based on a chunk of metal. A chunk of metal was just a convenient way of checking your etalons.

First they defined a meter. It is based on the length of the line from equator to the pole going through Paris. They measured the line and divided it by 10 million.
Since it is difficult to calibrate your 1m etalon by lying a ten million of them in a row, they made a standard example in a form of metal rod.

Then they defined the Kilogram. They took a liter of pure water, with the defined temperature and ambient pressure and got the first Kilogram.
Oh ... liter ... it is one thousandth of a cubic meter. A cube with side 1decimeter.
Remember, that was in 1790, so since then our need for precision changed somewhat and now we need to have those units defined in a more precise way.

Re:The kilogram is based on a chunk of metal?

[Dunavant]

Fahrenheit is the superior measurement. Water boils at 212. It freezes at 32. There is a 180 degrees of difference there, just like there is 180 degrees of difference between North and South. Checkmate.

Re:The kilogram is based on a chunk of metal?

[JesseMcDonald]

you might as well just use decimal millimetres or centimetres in multiples of 12 "blocks"

The base unit isn't the issue. The problem is the prefixes, which are based on powers of 10, not 12. For example, if you pick centimeters or millimeters as your base, dealing with meters (10^2 or 10^3 units, rather than 12^2 or 12^3) becomes very awkward. If you just ignore the SI prefixes then you're not really using the metric system, even if you happen to have an SI unit as your base. After all, even the traditional Imperial units are defined in terms of SI base units these days—that doesn't mean you're using metric when you measure lengths in inches and feet.

Base 10, being divisible only by 2 and 5, is convenient for writing decimal expansions, but not much else. Base 12, or better yet base 60, would have been better from the P.O.V. of simplifying the use of common fractions in manual arithmetic, while base 2 would have been ideal for binary computers.

Re:The kilogram is based on a chunk of metal?

[stasike]

When I see drill bit sizes defined like 3/64" I always say ... WTF?
When I see 1.2mm I know exactly how big it is.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

"No one cared about the weight of supper in terms of the speed of light in a vacuum, they cared about having enough to heat and eat through the winter."
Yeah, that's why all people who used metric went extinct when there were no calculators, you know, because they just couldn't get the amount of wood right and couldn't measure how much flour to make bread and not being able to build houses, because they couldn't divide a piece of wood in 3,4,6,8,9 and 12.

Re: The kilogram is based on a chunk of metal?

[j-beda]

I think you missed the point. People in France speak and think in French because that's what they're used to. Force them to adopt English as their national language and you'd have riots and pandemonium. Even if it held officially, people would use French over English anyway. That's what it's like for the common man to change their language of measurement.

Very true, but every other country in the world has switched, going through some pain in the process, but comming out of it eventually. Let us spare our great-grandchildren the pain and do it now quickly rather than continue to spread it out over the next dozen decades.

We have already lost this fight. Bit by bit, parts of every industry that interacts with the rest of the world has slowly moved to metric. The relatively small pain of this slow transition integrated over the huge time it is occuring is much less than the greater pain over the shorter transition period that every other country that previously used a non-metric measurement system ended up experiencing.

Re:The kilogram is based on a chunk of metal?

[lgw]

could still successfully figure out how to use a pair of oxen to spread four bushels of seed over a virgate (with a peck left over)

It's an interesting note on the history of muscle-based farming that the standard amount of land one guy and his animals would farm in a season gradually increased from 30 acres (a virgate) to 40 acres, and along with that the amount of food you'd expect a family to live on.

You also see "blocks" (as in city blocks or neighborhood blocks) commonly as 1 furlong in medium population density areas in the US (city blocks tend to be smaller).

Re:The kilogram is based on a chunk of metal?

[j-beda]

The point is that the "benefit" people have from the metric system is that it's base 10. The Imperial system as used in the US is base 10 when it's actually useful to be base 10 and not base 10 the rest of the time.

The real "benefit" is that the system is used by more than 6 billion people (18%), while the US comprises only about a third of a billion people (. In an ecconomic comparison, the US GDP is about 17 Trillion, while the world GDP is around 77 Trillion (22%)

Unless you think your arguments are strong enough to convince everyone else to switch from SI to US, the argument for switching just to be like everyone else is pretty strong.

Re:The kilogram is based on a chunk of metal?

[Gilgaron]

Sometimes, anyway. You'll find plenty of UK woodworkers use the Imperial system because it you are designing furniture for human proportions than the imperial system based on human proportions makes sense. Cooking, however... sure that's just whatever people are used to. And of course even Americans use metric at work doing science.

Re:The kilogram is based on a chunk of metal?

[phantomfive]

Plus, plug SI into Metric and quickly, in your head, with only moving zeros calculate how much energy is required to heat some water, from that how long it will take given a specific wattage, or how much a given volume of water weighs (and if you can recall its density, thus how much something else weighs) and from that how much force it will exert on the surface it sits on,

No one calculates that outside of the science world. And in the science world, everyone uses metric (even in the USA).

Re:The kilogram is based on a chunk of metal?

[cdrudge]

No. First they defined a gram, realized the temperature they defined it at was at it's most stable temperature point and not most stable density point. They also realized that 1 gram wasn't very practical for measuring things due to it's small size. So they made a object out of a stable piece of metal as close to 1000 times their original definition at it's most stable density and 1 atmosphere.

At that point of ratification, they declared that the piece of metal that was made to equal 1000 times the corrected definition of gram was a kilogram. From that point on, yes, a kilogram was based on a chunk of metal. Ever since then, all other kilograms used for calibration are calibrated based on an offset from that prototype.

Re:The kilogram is based on a chunk of metal?

[bmo]

I believe in the 18th century, this was intended to be one ten-millionth of the distance from the pole to the equator.

I maintain that if Gunther, in 1620, made his chain 1/100'th of a nautical mile (1 minute of longitude at the equator) rather than 1/80th of a statute mile, we would have never ever heard of the metric system.

1 nautical mile is 92.0624 chains

If he had adjusted his chain a mere 8 percent smaller, to make it 100 chains, it would have been adopted widely by navies and merchant marines around the world instead of just surveyors.

But instead he catered to the land-measurement guys and is now largely forgotten except by nerds like me.

--
BMO

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

1/3 of a metre is milimetres? Pretty fucking easy. 1m = 1000mm. 1000/3 = 333.3333...

It's not exactly rocket science. And I say this as an american.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

what, out of interest, is your best pro-imperial argument?

Easy... an imperial pint is larger than a standard (american) pint... and more beer for your buck is better.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

An ellipses in the educated world indicates there is more to be said. So what do you want to say?

Re:The kilogram is based on a chunk of metal?

[bobbied]

You missed the point, but I think you know it.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

The reason why 60cm is the width of choice has little to do with math and more to do with practicality. Traditional carpentry, masonry, and other craftspeople kept the surface of tables, desks, counters, and such to an arm's length from shoulder to fingertips as to allow people to reach the back easily. Traditionally that length was two feet, or 24 inches. Converting to metric you get just shy of 61cm. Now 61cm isn't too fun to work in as a metric carpenter or you'll end up with silly units like 305mm. Round down for, again, practicality and there's your 60.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

1/3 of 9 meter = 3 meter? What's so difficult about it?

But that's not the reason why the metric standard has been introduced. Every city had it's own reference for inch, feet, elbows, miles, ... If you needed to buy materials from a neighboring city you had to convert from one inch into the other. If you had to buy materials from all around you had to convert many times and would still have materials in the wrong size. Some places even used a decimal system, like 10 inch in one elbow, while the other region used 16 inch in one elbow, but most used 12 inch in one elbow, expect where they used feet, and so on. Sometimes a inch in one city was twice as long as the inch in the city 20 km to the east. It was impossible to progress into the industrial age with all these competing standards.

The metric system made it possible to buy products from the other side of the world with the reassurance that the same reference was used. Americans seem to forget why the metric system was introduced in Europe. It was not like Europe used the American Imperial system all over the continent. Many different standards and references where used which made interregional trade very difficult (expect for trade goods that didn't need exact measurements).

Re:The kilogram is based on a chunk of metal?

[Kjella]

And the reference kilogram has been losing weight, which means all of us have steadily started weighing more and more as time goes on.

I've heard a lot of creative excuses for the spread of obesity, but that was a new one. Of course blaming the French is not exactly new, but I think Fre... sorry, freedom fries have more to do with it..

Re:The kilogram is based on a chunk of metal?

[bobbied]

It depends on what you are doing.... If you are framing a house, working in meters might be a bit cumbersome and using centimeters is going to involve a lot of digits. A 2"x4" (actually 1 1/2 x 3 1/2) stud (38x39 mm) framed wall on 24" centers where you mount a 4'x8' sheet of plywood is going to be a bit of difficult math involving 4-6 digit numbers to set up, measure and construct. It's not that you cannot do it in SI units, only that because the lumber is using SAE units, it's much easer to go the feet/inches route.

Re:The kilogram is based on a chunk of metal?

[AmiMoJo]

That makes no sense. If you pick inches then dealing with feet, yards, miles, furlongs and all other imperial measurements is very awkward. Converting to volume etc. is even more difficult.

There is nothing wrong with ignoring SI suffixes. Engineers do it all the time. They usually just do everything in mm or M.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

No one who has lived with metric for their whole live has an issue with this.

People who think in the metric system do not use fractions for their measurements. The metric system is decimal, so we just write everything as decimal numbers up to the required precision. You may think that using fractions is infinite precise. But reality, and measuring is always done in reality there is no infinite precision.

In reality we have to specify the precision we are working in. We can either do this explicitly by adding a +/- precision numbers, but we can also do this implicitly using decimals by writing down the decimal digits up to the required precision. We have learned the implicit precision method from a very young age.

The decimal system allows for an implicit notation for precision (+/- half the lowest significant digit notated).
- 15 m means a precision of +/- 0.5 m.
- 15.0 m means a precision of +/- 0.5 dm
- 15.00 m means a precision of +/- 0.5 cm.
- 15.000 m means a precision of +/- 0.5 mm.

Re:The kilogram is based on a chunk of metal?

[bobbied]

As an electrical engineer too, the SI system is great....

However, I've done some construction work in my day and I much prefer SAE measurements when doing that. 4' = 121.92 cm and putting studs on 24" = 60.96 cm centers to match up to that plywood that covers the wall? Yea, I'll do that in feet and inches.

It depends on what you are doing...

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

one ten-millionth of the distance from the pole to the equator. The former is obviously a better definition because Earth is not perfectly spherical.

Why is non-sphericity a problem? The original definers and surveyors knew perfectly well about the Earth's ellipsoid, and how to compute distances on its surface.

The reason this was chosen was because nobody owns the planet, and it avoided the problem that had foundered every previous attempt at large-scale standardization: huge politics over *whose* yard would be standardized.

The one thing they allowed themselves was to define the arc through the Paris meridian, but everyone agreed it would make almost no difference.

It was measured by basically surveying an arc the height of France, and extrapolating mathematically based on the latitude angles of the top and bottom. But the survey had some error (in their defense, the French revolution washappening at the time, and one of the surveyors spent time in jail for "suspicious activities"), so the conversion isn't perfect.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

We'll just nuke the metric users instead. Problem solved.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

You would find UK woodworkers are doing this because woodworkers grew up in the imperial system.
I know Dutch wood workers are doing everything in metric, because we switched over to metric a lot earlier.

In fact long before the Dutch switched to metric our imperial system was rounded to the metric system. For example some people still use 'imperial' during shopping; a Dutch ounce is exactly 100 gram, a Dutch pound is exactly 500 gram.

Re: The kilogram is based on a chunk of metal?

[turbidostato]

"Force them to adopt English as their national language and you'd have riots and pandemonium."

But we are talking here about simple measures, nothing as complex as a natural language.

And regarding numbers, even French went not so long ago from Francs to Euros, having to change all their money-related devices, as did much of Europe, without too many riots and pandemonium. So no, forcing a language is not like to change their language of measurement for the common man.

Now, you are right in that being familiar is a very strong force, and that's why it won't happen unless there's a legal pressure to do so, just like Euro in EU.

Re:The kilogram is based on a chunk of metal?

[jbengt]

You are incorrect. The length of the meter is currently based on the speed of light and a standard interval of time. The length of a US foot has been based on the meter for well over a hundred years - except for states that haven't converted their land survey data to standard feet. Those states have two "feet" in play: US standard feet for most commerce, and survey feet for land surveying. Before basing the yard on the length of a meter the yard was based on the length of a standard yard-long metal bar.

Re:The kilogram is based on a chunk of metal?

[KingMotley]

As an American, that is a silly argument. Just throw the SAE crap out the window, and use measurements that actually make sense. Stop using 2"x4" lumber, which isn't actually 2"x4", and start using 5cm x 10cm instead. Feel free to actually make it 4cm x 8cm and call it 5cm x10cm if you want.

Re: The kilogram is based on a chunk of metal?

[AvitarX]

Is imperial really used anywhere?

I know US customary units are common here in the US, but I doesn't think the imperial system was used anywhere, except for people giving weights in stones.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

The original design spec for a metre was one 10 millionth the distance from the equator to the pole along a meridian of longitude passing through Paris, France. Among other things this makes the circumference of the Earth roughly 40 million metres, or about 40000 km (varies depending upon where you measure it because the Earth isn't a perfect sphere or ellipsoid). Only later was an estimate of this length inscribed onto a metal bar.

Re:The kilogram is based on a chunk of metal?

[Sheldon_Cooper_1]

For that matter, 1/3 inch in 64ths, please.

And why would you want to express 1/3 inch in 64ths? Pick a more natural unit like barleycorns.

Re:The kilogram is based on a chunk of metal?

[Jappus]

For that matter, 1/3 inch in 64ths, please.

21 1/3 64th, exactly. Now, 1/3 meter in millimeters, please?

333 1/3 mm; exactly.
See? Same thing.

The actual point here was that shifting that value to meter or kilometer or femtometer is all just a matter of moving the decimal dot. No need to involve fractions; unless you already had fractions before or shift the value below 1.0 (why would you?).

Problem is, you can't do that with Imperial measurements because it has different units of measurements for the same thing, and they do not cleanly convert into each other, since their base is different. In metric the base is always the same (10) and there is always just one unit for a measure.

The base could even have been 2, or 12, or 94467. Would not have mattered (much). The beauty of metric is that ALL units have the same base and thus freely convert without artificially forcing you to use fractions.

This is why: m/s, km/s, mm/s, nm/Ts -- they all convert "cleanly" into each other.

You can easily get the same out of the Imperial system, if you keep only one unit for each measurement, and use SI prefixes to alter the magnitude. If you'd only use foot or mile or yard or inch, you'd reap the same benefit as the metric system.

Point is: The actual unit does not matter, as long as the base is always the same.

Re:The kilogram is based on a chunk of metal?

[camperdave]

1/3 of a metre is 333 1/3 mm exactly. (hey, if you can do a third of a sixty-fourth, then I can do a third of a thousandth). That's not the issue. The issues are that the US customary system almost always uses multiple units for the same measure: A person is 5'7 1/2" and weighs 157 lbs 6 oz. Feet+Inches+fractions. Pounds plus ounces. Conversion are always happening. Further, the type of unit depends on what you're measuring. A pound of gold weighs less than a pound of feathers? Where's the sense in that? Landmarks surveyed to be exactly a mile apart are 63360 1/8 inches apart if you measure them by ruler. In SI, it doesn't matter you're measuring the mass of plumage or of precious metals, the unit is the same. It doesn't matter if you are surveying or measuring, the unit is the same. Length is length. Mass is mass.

Re:The kilogram is based on a chunk of metal?

[JesseMcDonald]

If you pick inches then dealing with feet, yards, miles, furlongs and all other imperial measurements is very awkward.

First, those units do not form a consistent base-12 or base-60 unit system—I wasn't trying to hold up Imperial units a some kind of gold standard. Yards fit into the system naturally enough, as a divisor of 12, though they wouldn't be a base-12 unit. Miles and furlongs, on the other hand, are fairly arbitrary. Second, I think we have different ideas about what is "awkward". Measuring feet in terms of inches in base-12 is not awkward at all; it just means multiplying by the base. In base 12, 1 foot = 10 inches; 10 feet = 100 inches; 100 feet = 1000 inches. This is an awkward series of ratios in base-10 (6/5, 36/25, 216/125).

The real advantage comes when you consider fractions. One third of a meter is an awkward repeating decimal with no exact representation in any SI base unit, but would simply be 0.4 (or four of whatever we called 1/12 of a unit) in base 12. The same goes for 1/6 and 1/12. (And in base 60, 1/15 and 1/30. If base-12 has a flaw relative to base-10, it's that unlike base-60 it has no exact representation for 1/5. But thirds are more common than fifths.)

Re:The kilogram is based on a chunk of metal?

[jbengt]

If you just ignore the SI prefixes then you're not really using the metric system, even if you happen to have an SI unit as your base.

That's not the big advantage of the SI system, anyway. The advantage is that compound measurements, like energy = force x distance or mass x velocity^2 don't need conversion factors.

Re:The kilogram is based on a chunk of metal?

[camperdave]

There was also the "length of a pendulum that has a half period of one second", and "1650763.73 wavelengths in a vacuum of the radiation corresponding to the transition between the 2p10 and 5d5 quantum levels of the krypton-86 atom" definitions. Also don't forget that there were three different chunks of metal a various times that had the distinction of being the prototype metre.

Re:The kilogram is based on a chunk of metal?

[Rising Ape]

The US doesn't even use the Imperial system, as it wasn't standardised until after the USA gained independence. So with imperial units, "a pint of water weighs a pound and a quarter", but the US saying is "a pint's a pound the whole world round" (hah!).

And then there's the mess of Troy vs avoirdupois weights. At least everyone agrees on what a kilogram is (well, the definition anyway).

Imperial/US/other traditional measures aren't more convenient for everyday living, they're just more familiar.

Re:The kilogram is based on a chunk of metal?

[jbengt]

. . . but Imperial does have one major thing going for it - Easy divisibility by low prime numbers.

That's why I do all my measurements in base 174,636,000 (2^5 * 3^4 * 5^3 * 7^2 * 11)

Re:The kilogram is based on a chunk of metal?

[sudon't]

Also, yes, everyone is aware of the physical basis for the kg. What about your pound? Is it based on something the "metric-ers" haven't found yet? Oh wait, it's based on the kg...

Obviously, the pound precedes kilogram, so it is not "based" on the kilogram. It is referenced to the kilogram, which itself has become too fuzzy for precision measurement. Hence the desire to find a more precise reference. All measurements are essentially arbitrary, and convertible.

I agree that the math is easier in metric, but since I didn't grow up using metric, I find working with Imperial easier because I "know" how long a foot is, and how much a pound weighs, etc. But, if metric were imposed upon us, like it was in Europe, we would eventually get used to it. Certainly our children would.

Re:The kilogram is based on a chunk of metal?

[ericloewe]

The foot is a rather awkward unit to use. It's too short for practical use in daily living and it's too long to be of much use otherwise.

I hope the above illustrates just how profoundly idiotic statements such as yours are.

Re:The kilogram is based on a chunk of metal?

[ericloewe]

How nice then that all imperial units cleanly divide by 12.

Oh, wait,

Re:The kilogram is based on a chunk of metal?

[camperdave]

No, the original definition of the metre was the length of a pendulum whose half period was one second.

Re:The kilogram is based on a chunk of metal?

[bobbied]

So.. You want to totally retool the entire construction industry so you can use the metric system? I'd be laughing but I think you are serious and might take offense.

Re:The kilogram is based on a chunk of metal?

[jbengt]

No one calculates that outside of the science world. And in the science world, everyone uses metric (even in the USA).

I'm in the engineering world, and I calculate those sorts of things all the time. And in the engineering world, everyone uses traditional US measures (almost everyone in the USA, anyway)

Re:The kilogram is based on a chunk of metal?

[tkdack]

That's why most house framing material is based on multiples of 300mm.

e.g.: 1200x2400mm (see http://www.boral.com.au/plaste... for more sizes)
300mm, 450mm or 600mm centers
1800mm, 2400mm or 2700mm lengths of timber

And 300mm is pretty close to 12 in

1 1/2 x 3 1/12 is more like 38x90 mm

Re:The kilogram is based on a chunk of metal?

[AmiMoJo]

Still makes no sense. If you know you want to use those odd fractions then just pick a multiple of 12m. It's as arbitrary as 12". In fact 36cm is pretty close to 12" anyway.

That's what seems so ridiculous to me. People argue that base 12 is somehow an advantage of imperial measures, but they write them in base 10. Decimal.

Re:The kilogram is based on a chunk of metal?

[JesseMcDonald]

The advantage is that compound measurements, like energy = force x distance or mass x velocity^2 don't need conversion factors.

Right, and there is no reason why you couldn't keep the same fundamental units and just use prefixes and written notation adapted for base-12 rather than base-10. As long as the units are consistent there would be no need for conversion factors.

Re:The kilogram is based on a chunk of metal?

[phantomfive]

That's a good point, construction, cars, etc, use traditional US measures when it's not problematic.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Just because it's called 'foot' does not mean everyone has the same lenght foot.

Re:The kilogram is based on a chunk of metal?

[bobbied]

I'll make the point simpler for you..

What's easier to write down: 8' or 2400mm? --> 8'

Get it?

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

> A metre is defined as the distance light travels in 1/299792458 of a second.

A choice that shows how truly idiotic the scientists of the day were, when they should have made it an even 1/300000000

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

The metre was officially defined as 1/10,000,000th the straight line distance between the North Pole and the Equator, through Paris, France.

It's why everything's in French (why the official term for "metric" is SI, or Systeme Internationale... French!).

That's why they call it a "royale avec fromage", instead of a quarter pounder with cheese.

Re: The kilogram is based on a chunk of metal?

[Anonymous Coward]

Base ten is objectively worse than some other bases, like 12 or 60, for many reasons. Metric sucks.

But Imperial is entirely inconsistent in this regard. There is no consistent base, and while many bases are better than 10, they're still not optimal. So it sucks, too.

Can we all agree both systems suck? And depending on context, one might suck less than another. Maybe metric is better overall, but it would still suck. And vice-versa for modern US Imperial.

Re:The kilogram is based on a chunk of metal?

[I'm New Around Here]

You can't do simple multiplication without a computer?

Re:The kilogram is based on a chunk of metal?

[BadDreamer]

Engineers calculate things like that all the time, and all engineers except the ones in the US and Burma use Metric.

And I also do that all the time, in my head, quickly and easily. In my work, when trying to figure out why a test failed in a nasty way, and when estimating things like if the cooling for a test will be sufficient, or if the power supply will manage what we expect of it given temperature ranges, energy requirements, humidity evaporation, whether a construction is solid enough to hold up the test subjects and other things. Also in my home and hobbies, when deciding what to purchase, or whether a specific tool can solve a specific problem in adequate time, or whether a construction will hold up to what I intend to subject it to. Pretty much none of it requires conversion, and usually I don't even need a calculator. That you don't do it is probably because you don't know how to.

Re:The kilogram is based on a chunk of metal?

[lars_stefan_axelsson]

Now 61cm isn't too fun to work in as a metric carpenter or you'll end up with silly units like 305mm.

Which is exactly my point. 60 is a very good number to use in that context. Now, of course if you were to try and go "metric" you could opt for 50cm, i.e. "half a meter" which was indeed an earlier standard for some appliances etc. but it never really caught on.

Claiming that imperial units are more "natural" is just silly. And divisibility is more a question of the number, not the unit. 13 inches isn't any easier to divide into three than 33 centimetres. Quite the opposite. (And if you don't like the conversion, the error is just over 6 ten-thousands, that's as near as damn it).

Re:The kilogram is based on a chunk of metal?

[lars_stefan_axelsson]

No, it means that something is left unspoken. Hence I'm not speaking it. If I didn't it wouldn't be unspoken, now would it?

[...]

Re:The kilogram is based on a chunk of metal?

[Sique]

This was the proposal of Jean Picard in 1668, but the actual measurement that led to the fabrication of the Metre prototype in 1799 was the distance between Northpole and Equator.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Kelvin is the only true logical temperature system.

Since you say that Celsius is as arbitrary as Fahrenheit and then state that Kelvin is the only logical system, I take it you are unaware of the Rankine scale.

Re: The kilogram is based on a chunk of metal?

[KingMotley]

No, I'd suggest just using tools from the rest of the world. Or are you suggesting that the rest of the worlds construction workers are just so much smarter that they can do it while the US construction worker is incapable of doing things in multiples of 60cm?

Re: The kilogram is based on a chunk of metal?

[bobbied]

No, I'm suggesting that construction workers would not like having to replace the majority of their measuring tools due to the costs involved, or, if they do remodeling, have to maintain two sets of measuring tools. Tools cost money and last time I worked in the trades the pay was not that great and I had to supply my own tools.

I'm saying that the industries that supply construction materials based in SAE measurements would be loathed to retool their factories..

I'm saying that the building codes which are enshrined in law based on SAE measurements would be hard to get changed because it would literally require hundreds of thousands of local governments at the city, county and state levels to coordinate their regulations and do it at the same time.

I'm saying that it doesn't matter if we switch the industry over or not, houses will still get built generally the same sizes in the same amount of hours.

I'm saying that it doesn't matter if they use SAE, so why go to all the pain and expense of making them do metric?

I'm saying let the economic forces decide what standard of measurement gets used where and just make sure conversion standards exist...

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Celsius is just as arbitrary as Fahrenheit and both are base 10.

Kelvin is the only true logical temperature system given that 0 K is absolute zero but it might be impractical to use up to five digits for half (or quarter) degree increments on thermostats to handle the hundreds of degrees kelvin that room temperature is at.

Imperial is shit but metric isn't perfect either.

BS Rankine, it's Fahrenheit adjusted to absolute zero same as Kelvin is Celsius adjusted.

Re:The kilogram is based on a chunk of metal?

[rpstrong]

The foot is a rather awkward unit to use. It's too short for practical use in daily living

Quite wrong. The foot evolved from practical use - not from some numerical theory. If it wasn't practical for daily living, then how did it come about?

Re:The kilogram is based on a chunk of metal?

[ericloewe]

Of course it's wrong. It's just as wrong as the original statement.

For every scenario you quote in favor of one, I can quote one in favor of the other.

Re:The kilogram is based on a chunk of metal?

[BadDreamer]

The USA is 5% of the world, and no-one outside the USA uses Imperial in engineering.

Re:The kilogram is based on a chunk of metal?

[hr raattgift]

The metre and the second were closely related from the start; the relationship is through the hydrostatic equilibrium of an object of Earth's mass and angular momentum, both of which were fairly precisely understood in the late *17th* century, at least a hundred years before the SI metre was officially adopted.

There is a deep connection between the metre as the quarter-great-circle of the Earth and the metre as the length of a pendulum arm with a half-period of one second, which is unfortunately distorted by gravitational anomalies arising from crustal mass concentrations, tidal effects, and nonuniformities of the Earth's rotation that makes physical realization of a pendulum-based metre awkward (it can be done, but requires corrections based on time and location; it's a bit harder to do on a ship in less-than-calm conditions, however...).

The longitudinal survey definition won out because its errors at the time were smaller and the corrections were easier to generate and tabulate in almanacs.

The gravity-arm_length-time relationship is described here:

https://en.wikipedia.org/wiki/...

In any event, the metre is now mostly deparochialized in that it doesn't directly depend on the gravitational field sourced by the Earth or its rotation or orbit. You can make a practical realization of a metre anywhere in the universe where you can measure the speed of a massless particle.

Most people who grow up with exposure only to SI have no problem in using decimal fractions of SI units, including metres. Indeed, people who can deal with fractions have no problem applying them to SI units casually. Half a kilometre. Three quarters of a litre. Just like people who grew up with U.S. customary units will say things like half a gallon or a quarter of a mile.

People who are exposed only in adulthood to a different system of measurements are possibly frightened that they look ignorant or, worse, that they appear mentally unable to learn the new-to-them system.

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

Where are these UK woodworkers who did not grow up in Poland or Romania? Oh, that's right, they're working in Spain (or retired there).

Re:The kilogram is based on a chunk of metal?

[Anonymous Coward]

No, first they took the definition of the second, then took the known-with-precision-in-the-mid-17th-century seconds pendulum's arm length as the metre. The problem is that physically realizing a metre depended on time and position on the Earth due to gravitational anomalies arising from crustal mass concentrations, tides, non-uniformities in the Earth's rotation, the Earth's oblateness, and other effects which were discovered in attempting to standardize a unit of length using the seconds pendulum. The seconds-pendular metre was proposed by the Royal Society (in the UK), not the French, and was aggressively pursued by several well-known Americans (Jefferson, Franklin) in the 18th century.

There is a deep connection (through Earth's hydrostatic equilibrium and angular momentum) between the sidereal second and the Earth's radius that is *measured* by a seconds pendulum; this relationship was well understood and fairly precisely calculated in the 17th century. However in the late 18th century it was more practical to use celestial measurements of angle rather than chronological measurements to determine large-scale lengths (and position generally), and thus the length unit was based on 0.5 pi times the radius of the Earth, expressed decimally (1/4 the great circle distance ~ 1e06 metres). Because of known non-uniformities across different great circles on the geoid, one particular one was chosen, even though that particular great circle was known at the time to be inexact.

So, first came seconds (which were ancient), then came the metre (developed by Mersenne a century before SI efforts began), then came units derived from the metre (area, such as the hectare; volume, such as the litre), then came pressure (which depended on length or volume), then came temperature (which depended on pressure), then mass came along later and its definition depended in part on the metre and on pressure and temperature.

Re:The kilogram is based on a chunk of metal?

[dcollins]

"If you're a genuine 'imperial zealot' then what, out of interest, is your best pro-imperial argument? I'm curious because as far as I can tell, imperial is shit. And I say that as someone who has had to deal with both systems."

Generally, imperial is a "human-scale" system (https://en.wikipedia.org/wiki/Human_scale). If there's any advantage, it's that it makes approximations and estimations pretty easy. A foot is about a person's foot. A league is about how far you walk in an hour. Fahrenheit temperature of 0 is really cold, 100 is really hot (outside that range is life-threatening without exotic gear). A stone mass is about how much will start to slow you down if you carry it.

The divisibility by small factors (2, 3, 4, 6) is also nice for a lot of discrete applications. For precision measurements, modern science, continuous measures, and conversions, obviously that's where it starts to break down.

Re:The kilogram is based on a chunk of metal?

[dcollins]

"Their length unit is based on a physical cylinder of metal."

Not since 1960: https://en.wikipedia.org/wiki/History_of_the_metre

Re:The kilogram is based on a chunk of metal?

[I'm New Around Here]

Hi. Thanks for the reply.

Actually, I was meaning to refer to the metal cylinder in the article, which is the basis of the kilogram. That's even what's in the title. But halfway into my thought it changed from the kilogram to the meter. I don't know why.

I do think it encouraged a lot of lively discussion, so my effort wasn't completely wasted.

Again, thanks for the correction.

Re:The kilogram is based on a chunk of metal?

[strikethree]

Hm. Mass is energy contained within a defined space. Shorthand is E=MC^2.

We have measurements for distance that are constant.
We have measurements for energy that are constant.

Can't the gram just be expressed as energy density? Does it have to be solid? If so, is it the expense of turning energy into matter that is preventing any properly equipped lab from having a perfect reference for the gram?

Re:The kilogram is based on a chunk of metal?

[rpstrong]

I think you misunderstand. My point is that SI units evolved from measuring things in everyday life, the metric system did not. Yes, we can come up with numerous scenarios - but I'd bet that the metric system comes out ahead in predominately scientific and technical situations, not everyday cases.

Re:The kilogram is based on a chunk of metal?

[ericloewe]

You can't even get your units' names straight and we're supposed to consider your opinion on units?
SI = Système International (des Unités). Base units are kg, meter, ampere, second, kelvin, candela (and mole, for some reason)
"metric" = anything that's not imperial units (SI, cgs (stupid little system), ...)
Imperial = System kept afloat by the idiotic argument that it's better for everyday use (when, in fact, ease of use is a function of use - familiarity, that is). The only reason it's usable for any semi-serious purpose is because every single unit is defined in terms of SI units.

Re:The kilogram is based on a chunk of metal?

[rpstrong]

Brain fade; mixing SI and Imperial is a particular mental typo that I often make.

  But I do recognize an argumentum ad hominem.

Re:The kilogram is based on a chunk of metal?

[ericloewe]

Questioning your knowledge/experience on the matter is not a personal attack. Don't victimize yourself.

Re: The kilogram is based on a chunk of metal?

[KingMotley]

And yet, the rest of the world has already done it, so I suggest that your assumptions on the cost of doing the switch aren't accurate.

As for the current laws regarding building codes, I doubt they are written with such a narrow margin that the conversion to metric would even matter. In the cases that they do, there is no reason why they have to be changed immediately. It's not like saying all pipes must be blue instead of red or some such. If the current law says x must be no more than 24 inches, then find the closest multiple of 60cm that is less than 24 inches and use that.

My sugar-free vanilla latte haven't kicked in...

[__aaclcg7560]

I thought the title read: "Klingon Conflict Resolved At Last"

Indeed, they have solved a massive problem.

[Anonymous Coward]

Keep it rolling...

Re: Indeed, they have solved a massive problem.

[silentcoder]

Now this is stuff that matter.

Re:The metric system is for cows

[Anonymous Coward]

The pro-imperial argument neatly summarised. Thank you kindly.

This could be an historic pun n-gram!

[Anonymous Coward]

I tried...

Still confusing.

[140Mandak262Jamuna]

My best understanding is: Time is defined as a multiple of time period of oscillation of cesium atom at some pressure and temperature. Length is defined as a multiple of a particular frequency light, frequency depends only on time already defined. Now the change is kilogram is defined as a formula based on Plank's constant, length and time both previously defined. Now we can define charge, temperature etc from these. Thus we claim that we have stable definition of the standards.

I am not sure *stable* is the right word. It is indestructible information not any physical object. It is readily reproducible, can make back ups etc. But is it stable? As our ability to maintain temperature and pressure improves the time period measured could change. As our measurement techniques improve, that too can change the measured time period of oscillation of that atom. Similarly our ability to measure the wavelength can improve/change and thus change the definition of meter. Further all our measuring devices are calibrated using current basic standards. So there is this issue of recursion and that can introduce drift.

As fat as I understand, kilogram is now based on *digital* information, so it is replicatable without loss of fidelity, archivable. Indestructible as long as there are governments, and the willingness, funding standard setting organizations .

But stable?

Re:Still confusing.

[gstoddart]

Apparently more stable than a block of something which sheds some matter over time, yes.

So, your choices are: 1) measure according to a physical object which can change over time, or 2) measure according to a known set of physical properties which can be reproduced.

And there's nothing to say over time as the science gets better they don't tweak this.

But, in terms of defining in terms of a measure someone can reproduce, it's gotta be better than "1kg is this artifact we made".

I mean, this is what we have now:

The origin story of Big K reads like a fairytale. The cylinder-shaped artifact was forged under the guidance of the General Conference on Weights and Measures (CGPM), which stated in 1889, as if by royal decree: "This prototype shall henceforth be considered to be the unit of mass."

For over a century, the kilogram was sealed within three glass bell jars beneath the International Bureau of Weights and Measures, where it was protected from dust, moisture, fingerprints, and other corruptions of the outside world. Big K could only be retrieved by a gathering of three custodians, each with a different key.
Gaze into the Crystal Ball

Forty identical sister copies were shipped abroad to calibrate kilograms worldwide. The cylinders were reunited only three times for comparison. Each time, Big K and its twins were delicately wiped with alcohol and ether, steam-cleaned, and weighed. In 1992, scientists were disturbed to discover that Big K had somehow become lighter than its siblings.

So, it's gotta be more stable than an artifact.

Re:Still confusing.

[Anonymous Coward]

But stable?

Most likely not. However the recent shift to a "forces of nature" definition does increase the likelihood that it has the potential to be useful in any environment.

By that I mean that the current state of gravitational theory indicates that significant gravity will affect the fundamental nature of time and distance. Since converting Plank's Constant to a measure of distance requires certainty about the speed of light in a vacuum and the universal gravitational constant, any deviation in the behavior of light or gravity that does not follow a predicted linearity from our test environment (which is, in the scale of observations, an extremely negligible amount of gravity) will potentially lead to calculated standards of measurement that do not match ones defined elsewhere using the same processes.
The good news on that front is that the scenarios currently imaginable that would lead to such a failure require a few steps of theoretical engineering past what would be needed for "fast" interstellar travel.

All that said, the bigger failing of the metric system is that the "base" units in most measurements are equally inconvenient to all users. As a partial workaround, tonne, kilogram, gram, and microgram are all seen as "base" units of mass for different purposes, and all of them are a little awkward in the scales that use them. Similar with kilometer, meter, centimeter (breaking the 1000 rule for that one), and micrometer. While there is an internal consistency to that, very very few situations span enough to actually care that such a consistency exists.
I could provide a separate monologue about the convenience benefits of base 12 or base 60 (the Babylonian 'minute') compared to base 10 for measuring purposes, but those are other rants for other discussions.

Re:Still confusing.

[Beerdood]

What I learned from this article, was that the metre was the initial arbitrary unit that formed the basis of the metric system (I think). The relationship is that 1kg of water = 1 liter = 1 cubic decimeter. But one of these had to come first, and as a result of an arbitrary unit. If a kilogram was slightly heavier or lighter, then that would have altered our metric measurements of volume and weight by a slight amount too

Another poster here mentioned that the meter was originally intended to be 1/10,000,000th of the distance from the pole to the equator, but it's been redefined twice, and now it's supposed to be X number of wavelengths of an line of krypton-86 . And then finally, this was redefined again in 1983 as the distance light travels in 1/299792458 of a second.

What I don't get it, shouldn't the kilogram have been defined and redefined then as the weight of a cubic dm of water each of these times then too? Why is there an attempt to base this on Avogadro's or Plank's constant?

Re:Still confusing.

[140Mandak262Jamuna]

All that said, the bigger failing of the metric system is that the "base" units in most measurements are equally inconvenient to all users.

It is not a failing of metric system, but it is due to pre-existing conventions. The benefits of metric system is not so much it could dislodge existing kings of the hill. It is the same reason why the weird keyboards from microsoft/Dvorak did not displace QWERTY. Same reason why linux struggled against windows. People who grew up with metric have no problem using kilometer or kilogram or meter. But in civil engineering, walls thickness and room widths are still in feet, but rebar rod dia are in mm, even in India. Had to do mental arithmetic when a nephew quoted his Paris apartment area in square meters.

Re:Still confusing.

[Bengie]

We've increase the precision of what defines a kilogram, but made sure it stayed within the accuracy of modern day measurements. As we get better and better at measuring, we can increase the accuracy of of our measurements with a fixed goal in mind. Even if that goal is arbitrary, it doesn't matter, everything is relative. The notion of concrete concepts are really just abstract concepts of emergent behaviors of an underlying relational system.

Re:Still confusing.

[Dragonslicer]

What I don't get it, shouldn't the kilogram have been defined and redefined then as the weight of a cubic dm of water each of these times then too? Why is there an attempt to base this on Avogadro's or Plank's constant?

No, because when talking about fundamental units, the gram is a unit of mass, not weight. The weight of a cubic dm of water changes if you move it, since the force exerted by Earth's gravity would be different. For defining the fundamental unit of mass, you'd have to use the mass of a cubic dm of water at some given temperature and pressure. That's just the mass of X water molecules in that volume, though, so now you're back to counting atoms.

Re:Still confusing.

[91degrees]

I guess the main problem is difficulty of getting a reference value. Measuring out an exact volume of liquid of exactly the right isotope levels (this will have an effect at the level of precision we're talking about), at an exact temperature and pressure is looking so difficult that it's starting to sound easier to fly to France, and go through the bureaucracy needed to use the reference kilogram.

Re:Still confusing.

[j-beda]

What I don't get it, shouldn't the kilogram have been defined and redefined then as the weight of a cubic dm of water each of these times then too? Why is there an attempt to base this on Avogadro's or Plank's constant?

The difficulty at various times in the past was that the accuracy available using various deffinitions was different. If we defined the kilogram of mass as being equal to the mass of one litre of water, the uncertainties in that definition would have been much greater than the uncertainties in measuring a standard chunk of metal and replicating that. The uncertainties arries in the purity of water obtainable, the temperature, pressure, humidity effects that would come into play, the uncertainties in creating a vessel with the exactly correct volume.

If your scales are accurate to nano-grams but your standard is only accurate to micro-grams, then you have a problem.

If you are using a chunk of metal, than your standard is going to be as accurate as your scales and you only have to worry about making sure your standard is not changing over time (which is why they treated it with such care). Once you have a standard definition that can be measured as accurately as the standard physical object, then the object becomes superfluous, but before that point it is better to just use the standard physical object.

Re:Still confusing.

[Anonymous Coward]

Parent has the right idea.

It's not so much that the artifacts we have aren't pretty good, but that the fact that an artifact exists at all. If you discovered another planet with life on it, how would you convey the value of a meter? A second? Because we have defined these based off of properties, we could explain to them how to construct a standard without physically sending one for comparison.

Switching the definition of the kilogram is no different. The idea is that both the Si sphere and watt balance can be reproduced from information alone, as well as remaining stable enough to be a better definition than we currently have.

BTW the kg artifacts do vary with time, as evidenced by occasionally comparing them with each other. However, with the current system, we can't know if collectively they gain or lose mass, since they are by definition 1kg.

Re:Still confusing.

[Anonymous Coward]

Not so long ago they decided to not make the 'time-definition' indirection for defining length. They now say 'the distance light travels in a vacuum for n periods of oscillation of an cesium atom"

Re:Still confusing.

[painandgreed]

It's not so much that the artifacts we have aren't pretty good, but that the fact that an artifact exists at all. If you discovered another planet with life on it, how would you convey the value of a meter? A second? Because we have defined these based off of properties, we could explain to them how to construct a standard without physically sending one for comparison.

In communication and giving them physical equations such as that for gravitational field, simple pendulum, gravitational and kinetic energy, and E=mC^2. Now, you have five equations to solve for the ratios between our units of mass, length, and time. Substitute in their own standards in the same equations and they have more than enough information to define our standards by however they define their own.

Re:My sugar-free vanilla latte haven't kicked in..

[oobayly]

Don't be daft, that'll never happen. It does however raise an interesting point - which will end first, Klingon conflicts or the Metric vs Imperial debate?

Need more coffee (and less Star Trek)

[Anonymous Coward]

Did anyone else read that as "Klingon Conflict Resolved At Last"?

Re:My sugar-free vanilla latte haven't kicked in..

[idontgno]

The Klingons will settle the Imperial v. Metric debate.

Because "Klingon Empire".

'Murica

[sjbe]

Does this mean the US can now join the rest of the metric world, or are we still in the quagmire?

No, apparently we prefer to remain the backwards rednecks of the world because... 'Murica.

Re:'Murica

[Anonymous Coward]

You don't see Americans arguing over the size of a pint or a pound. "A pint is a pound the world around." So there.

I'm laughing at the superior measuring system.

Re: 'Murica

[Anonymous Coward]

America uses both standards incase you haven't noticed. Both are taught at schools. Most cars these days have both. Road signs still use Imperial but that's mostly just because they haven't gone though the legal hoopla to change the format. Why the American person chooses one over the other is of no consequence. Why the American government still uses Imperial in the places that it does is that we haven't dedicated the resources to change the existing laws. Its not a vital issue to us. But it was an issue in countries where someone drove the effort to actually change the signs. We'd rather replace them when the appropriate opportunity comes along. Not wrong, just different.

Re:'Murica

[j-beda]

You don't see Americans arguing over the size of a pint or a pound. "A pint is a pound the world around." So there.

I'm laughing at the superior measuring system.

I am pretty sure that the "American" units have all been defined in relationship to the SI units. All the refinements of definition happen on the SI side of things and just get passed over to the US customary units side. Basically the US has been completely metric for a long time, and just divides all the lengths by (2.54 cm/inch) - which totally makes sense.

https://en.wikipedia.org/wiki/...

Re: 'Murica

[AvitarX]

Except pints we're not pints the world round.

Re: 'Murica

[Anonymous Coward]

the meter has been invented by the commie brutes. they did more than one mega kill event...

Re: 'Murica

[Anonymous Coward]

I'm confused, you're a pint?

Re: 'Murica

[jdschulteis]

But it was an issue in countries where someone drove the effort to actually change the signs. We'd rather replace them when the appropriate opportunity comes along. Not wrong, just different.

Back in the 1970s there was a big push toward metric in the US. Many road signs were replaced with ones that had both US customary and metric units. The next time the signs were due for replacement they went back to customary only. I think there's just too much inertia, similar to how we started minting dollar coins but didn't stop printing dollar bills.

Re: 'Murica

[KGIII]

I understand they were going to faze the dollar bill out but had to keep making them because we're weird. People kept, for some reason, collecting them as if they were rare treasures even though they were making a shit-ton of them. They were worried, as I understand, about there being a shortage of dollar units in circulation. Dollar bills don't actually last that long in the wild before they're returned to be destroyed. So it would have led to problems - at least that's what a documentary that I watched claimed. I've no idea if it is factual or not.

Re: 'Murica

[sjbe]

Back in the 1970s there was a big push toward metric in the US.

I know because I lived through it.

Many road signs were replaced with ones that had both US customary and metric units.

Which was the big mistake. They should have just gone ahead and gone metric. But we gave ourselves an out and couldn't be bothered to see it through.

Re: 'Murica

[Anonymous Coward]

Americans are simply afraid of change. Any change. Dollar coins are the scariest sort of change, the sort that jangles around in pockets and purses reminding you of that change and probably every other sort too.

Re:My sugar-free vanilla latte haven't kicked in..

[tehcyder]

I thought the title read: "Klingon Conflict Resolved At Last"

Same here. Even after I shook my head and re-read it.

Fuck lattes, it's quadruple espresso time and a bag of chocolate doughnuts.

Avogadro FTW!

[hackertourist]

The new definition involves counting exactly 60 200 000 000 000 000 000 000 000 000 hydrogen atoms.

Re:Avogadro FTW!

[donkwich]

Sixty octillion one hundred ninety-five septillion three hundred sixty-eight sextillion five hundred forty-one quintillion four hundred seventy-four quadrillion six hundred seventy-three trillion eight hundred twenty-two billion six hundred thirty-one million nine hundred forty-five thousand two hundred ninety-one, sixty octillion one hundred ninety-five septillion three hundred sixty-eight sextillion five hundred forty-one quintillion four hundred seventy-four quadrillion six hundred seventy-three trillion eight hundred twenty-two billion six hundred thirty-one million nine hundred forty-five thousand two hundred ninety-two... shit I lost count.

Re:Avogadro FTW!

[Anonymous Coward]

Worst summer internship ever.

Re:Avogadro FTW!

[Anonymous Coward]

(format t "~r" 60200000000000000000000000000)
sixty octillion, two hundred septillion

Re:Avogadro FTW!

[bobbied]

Worst summer internship ever.

Ah no way! It was a gas!

Here's the sphere in question

[Anonymous Coward]

https://www.youtube.com/watch?v=ZMByI4s-D-Y

Re:Can the "Paid Posts" go to the museum too?

[houghi]

I believe they are visible only for people who are logged in to prevent 'frist post' abuse.

Meter definition

[sjbe]

Their length unit is based on a physical cylinder of metal.

Not it is not and has not been since the 1960s. The metre is currently defined as the length of the path traveled by light in vacuum during a time interval of 1/299792458 of a second.

Re:Meter definition

[Anonymous Coward]

At least they picked a nice easy to remember number.

Or, they reverse-explained the measurement they were already using, which was based on false information (1/10000 of the distance between the north pole and the equator)

Re:Meter definition

[Anonymous Coward]

If metric is so much about "easier numbers", then why not change the damned meter to match 1/300000000 of a light-second instead of making it a retarded back-conversion to the existing length?

Fuck metric.

Re:Meter definition

[camperdave]

Actually, it never was. The metre prototype bars had an X-shaped cross section, not cylindrical one.

Re:Meter definition

[t0y]

The reference value is actually 1/c seconds. You only ever need it if you're doing math with the speed of light and the complexity is either there already or it makes it easy to co-relate with other c terms in equations. It's actually much simpler than using inches.... Try it.

Video of the SI sphere

[flink]

Veritasium did a visit to the facility where they were producing one of the spheres. You can see it here: https://www.youtube.com/watch?...

Re:My sugar-free vanilla latte haven't kicked in..

[AmiMoJo]

Klingons use kellicams as their unit of distance, and it appears to be decimal.

What temperature is the cylinder?

[Anonymous Coward]

A kilo is the cylinder mass at 0k?

Re:What temperature is the cylinder?

[wonkey_monkey]

And how fast is it moving?

Should Not Break from Liter Equivalent

[BrendaEM]

The relationship between the kilogram and the liter was the most elegant thing in the metric system, so why break it?

Re:Should Not Break from Liter Equivalent

[wonkey_monkey]

What's elegant about it? The kilo is "the only SI unit based on a physical object." That's not elegant at all.

And there isn't a direct relationship between the two, anyway. The litre is a measure of volume, not mass of a particular substance. They were related through the definition of the metre:

One litre of liquid water has a mass of almost exactly one kilogram, due to the gram being defined in 1795 as one cubic centimetre of water at the temperature of melting ice. Subsequent redefinitions of the metre and kilogram mean that this relationship is no longer exact.

There. It was inaccurate already.

Re:Should Not Break from Liter Equivalent

[UnderCoverPenguin]

At some point, the definition of the gram was refined to the mass of 1 cubic centimeter of water at water's maximum liquid density.

Was in some physics text I read in high school. A web search found several confirmations of that definition.

Re:Should Not Break from Liter Equivalent

[Anonymous Coward]

What is elegant is being able to tell how much x volume of water weighs without complicated maths. But generally this is only useful when you need a quick approximation (at which point you can also apply it to other liquids of similar density), and not a precise measure, so having it not be exact isn't a big deal.

Re:Should Not Break from Liter Equivalent

[cdrudge]

In 1975 the gram was defined as 1/100 of a meter cubed of pure water from melted ice. Or in other words, a cubic centimeter of water. Within 4 years, they realized they screwed up and made the water's temp at it's maximum density measured then at 4 degrees C. Also at the same time they realized the impracticality of defining mass with a small size of a easily impure liquid that evaporates so they made the all-platinum prototype that was equivalent to one cubic decimeter of water at 4 degrees C and 1 atmosphere. It was adopted that that was what a kilogram was. The object used to day is a physically improved version of that original all-platinum version made the standard in 1889.

Re:Should Not Break from Liter Equivalent

[j-beda]

The relationship between the kilogram and the liter was the most elegant thing in the metric system, so why break it?

This doesn't break it. Any changes to the precise value of the kilogram are going to be so small that you can safely continue to use the idea that one litre of water has a mass of one kilogram. Changing the definition of the metre from one based on the earth, to the reference piece of metal, to waveleghts of a particular type of light, to a distance light moves in one second did not change the litre-kilogram relationship because the litre-kilogram relationship in practice cannot be examined to the level of accuracy of the other relationships.

Re:Should Not Break from Liter Equivalent

[Lehk228]

but a liter of water at 4C is still a kilogram for every practical purpose and most impractical purposes. maybe using that will screw up your game of ice meteor billiards

Re:Should Not Break from Liter Equivalent

[cdrudge]

but a liter of water at 4C is still a kilogram for every practical purpose and most impractical purposes.

Seems to me that if in 1799 they were able to tell that 1L of ice water was only 99.9265% the mass of 1L of 4C water, the difference was significant enough for practical and impractical purposes.

They aren't making the measurements so that they can make a recipe, fill up a glass of beer at a bar, or figuring how far the next town over is. Those are all things were practical purposes makes close enough fine. What we're talking about here is THE standard by what all other mass measurements are derived from in modern society. Practical and impractical purposes isn't good enough.

Re:The metric system is for cows

[PPH]

SPHERICAL metric cows. In a vacuum.

Thank goodness

[JustAnotherOldGuy]

The last kilo I bought was off by almost 0.00000000000002%, and I was cranky for days.

Got a refund though, so it all worked out in the end.

Re:Thank goodness

[Anonymous Coward]

What did you buy with that refund money?

base 12 is better than base 10

[Anonymous Coward]

so base 210 (7*5*3*2) would be an even better one

Re:base 12 is better than base 10

[Anonymous Coward]

As a computer scientist, I'd like to throw in my vote for a base 2 system.

Re:base 12 is better than base 10

[lgw]

so base 210 (7*5*3*2) would be an even better one

This is why the mile is 32*3*5*11 feet. OK, so the 11 is actually in there for different reasons than divisibility: there was a tradition of measuring any goods with 10-20% slop built in for spoilage. For land, a furlong (220 yards) gives you a 200 yard field with room to build a fence or road, and still have room to turn the oxen for the next furrow over. (An acre, BTW, is a rectangle a furlong by a surveyor's chain - a very handy unit for land measurement at the time.)

It's not entirely a coincidence that a furlong is very close to 200 meters. That was a strong influence in making the meter somewhat larger than the yard.

Re:base 12 is better than base 10

[bobbied]

Makes 1023 the largest unsigned integer in the world because that's as high as you can count on your fingers...

oh, for crap's sake.

[swschrad]

I define the standard kilogram as the compression of fairy farts to fill a 36-inch weather balloon to a pressure of six say-whats.

that's as easy to figure out as that galloping nonsense printed above. count atoms, then convert, then convert, and then since it's silicon atoms, you can surely correllate the pull against an electromagnet (of undefined gauss, and its undefined measurement). and then put that on a balance scale, and slap your slop on the other end until it's a kilogram.

honestly, somebody was being paid by the syllable to write that definition, and triple payment for words over ten syllables, whether they are in the dictionary or not.

Re: oh, for crap's sake.

[Anonymous Coward]

The point is not for it to be simple. The point is for it to be invariant. That means they need to relate it directly to something that we think will never change. The meter is related to the speed of light. They want to relate the kilo to the mass of one silicon atom, that inevitably means a conversion factor.

Imperial measures are set up so that you don't ha

[Anonymous Coward]

> Imperial measures are set up so that you don't have to do a lot of converting.

This one was funny.

My Dealer

[Frosty Piss]

When I go to my dealer and ask for a kilo, I know I get a kilo.

Re:My Dealer

[davester666]

I love the small of talcum powder in the morning.

constructs of interest

[fyngyrz]

Yeah! Pretty soon you'll have to have a set of reference carbon nanotubes around just to build a doghouse!

Fyngyrzians

[fyngyrz]

Everything should be in hexadecimal. Divisible by 2, 4, and 8 just fine. We divide things into halves, quarters and eighths more than we do anything else. Base ten gives us divisible by 2 and that's it. Pah.

As for the other direction, hex is replete with useful multipliers. Just as your computer will show you. :)

And of course binary folds perfectly into hex, and vice-versa. Base ten? Oy. That's why floats don't do an accurate job when you try to do something as mundane as represent one tenth accurately. But 1/4? 1/8? etc.? No problem.

Ever see a DAA instruction in an early computer instruction set? "Decimal Adjust." So the early CPUs could actually (sort of) do base ten math without screwing it up...

Radians: 2pi / circle
Gradians: 400/circle
Fyngyrzians: 256/circle

I actually used 256/circle in some old arcade games I wrote. Very, very convenient when you're dealing with the native capabilities of Z80s and 6809s and the like. Makes for excellent lookup tables with byte indexes.

Re:Fyngyrzians

[phantomfive]

Everything should be in hexadecimal. Divisible by 2, 4, and 8 just fine.

Fail at thirds, though. Base 12 is better.

Re:Fyngyrzians

[Anonymous Coward]

Why do you think metric is base 10? - it's just as easily base 100, which is divisible by 1, 2, 4, 5, 10, 20, 25, and 50.

Re:My sugar-free vanilla latte haven't kicked in..

[Anonymous Coward]

I thought the title read: "Klingon Conflict Resolved At Last"

I read it the exact same way. Glad to know I'm not the only one.

Re:The metric system is for cows

[91degrees]

You are all Cows. Metric Cows!! Cows say Moooo. MOOOOOOOOOO! MOOOOOOOOOOOO! MOOOOOOOOOOOOOO cows MOOOOOOOOOO! Moooooooo say the cows. YOU PARIS COWS!!!!

Metric cows say Moooooooooo. Imperial cows are the ones that go Mooooooooooooooo, Mooo, or Moooooooooooo

Le Grand K

[Anonymous Coward]

I thought Le Grand K was a french rapper.

Re:Can the "Paid Posts" go to the museum too?

[Anonymous Coward]

Frist post!

the Australian metric system abolishes cm

[peter303]

I am not sure this has another name. It calibrates everything in thousands or thousandths with three digits of precision. Use no decimal places or decimals. Just change to next 1000x prefix. This was found to significantly reduce error in the construction trades and medicine doses. Construction scrap was cut 80%-90% saving money.
It does look a little weird at first to see blueprints entirely in millimeters.

I heard this system at Nerd Nite.

Re:the Australian metric system abolishes cm

[Anonymous Coward]

In construction in Australia everyone uses millimetres.

  Which are very easy to convert to metres or Centimetres or Kms.

  The great thing about Millimetres, is you know how accurate you need to be. To the mm. If I say a room needs to be 10m how accurate do you need to be? +/1 .5m? If I say it needs to be 10,000mm then guess, what, it should be 10,000mm +/-0.5mm.

  Everyone thinks mm (refered to as Mils). Mistakes still happen and not everything is perfect, but no one blames the measuring system for imperfections.

  I have not idea how quantity surveyors survive in the US. How many gallons of paint (or tiles) will be required to paint (or tile) this complicated curved 3D building? How quickly can you do this calculation.

  Australia converted to the metric system. It allowed things like the Opera House to be built.
https://en.wikipedia.org/wiki/Metrication_in_Australia

"The building industry was the first major industry grouping in Australia to complete its change to metric. This was achieved within two years by January 1976 for all new buildings other than those for which design had commenced well before metrication began. The resulting savings for builders and their sub-contractors has been estimated at about 10% a year of gross turnover.[13]

In this the industry was grateful to the SAA (now Standards Australia) for the early production of the Standard AS 1155-1974 "Metric Units for Use in the Construction Industry", which specified the use of millimetres as the small unit for the metrication upgrade. In the adoption of the millimetre as the "small" unit of length for metrication (instead of the centimetre) the Metric Conversion Board leaned heavily on experience in the UK and within the ISO, where this decision had already been taken.

This was formally stated as follows: "The metric units for linear measurement in building and construction will be the metre (m) and the millimetre (mm), with the kilometre (km) being used where required. This will apply to all sectors of the industry, and the centimetre (cm) shall not be used. the centimetre should not be used in any calculation and it should never be written down"

Australia is just a better version of the UK, Canada and the USA combined, put on its own mega island in a nice region and baked in the sun for a million years.

originally a volume of water

[peter303]

A liter is 10^3 cm. A liter of water at one bar and 4C weighs one killogram. A chunk of metal weighing the same was more convenient manage than water.

Sheldon?

[Anonymous Coward]

Is that you Sheldon?

Kilogram conflict resolved at last...

[Anonymous Coward]

...when one scientist threw the weight at the other, knocking him unconscious. First one won.

BBC documentary about measurements

[t0y]

This is dicussed in the documentary: The Measure of All Things. Relevant section linked with the timecode but the whole documentary is on topic of this post.

Planck's Constant isn't a constant

[Anonymous Coward]

Planck's Constant isn't a constant.

Go ahead, investigate, prove me to be correct. I don't have the resources to do it myself, but I'm sure it's true.

Enjoy modding me negative infinity :)

No one is asking?

[ebvwfbw]

So how far off are our "standard" metric unit Kilogram?

Standards are great. There are so many of them to chose from.

Re:My sugar-free vanilla latte haven't kicked in..

[Anonymous Coward]

"Klingon distance is an interesting concept..."