Metric System Rewrite

[Kerbart]

Tbh, I've never seen or heard a lot of the prefixes used. Deca, deci and hecta are pretty much unused (except maybe for hectares). Almost everything in everyday scales is milli, centi and kilo. You'll get into greater and lesser than that in science and engineering, even then you'll never hear anybody talking about megagrams or exameters. Very big or small stuff is just expressed in scientific or engineering notation.

Let me see... beer is generally sold in hectoliters (not at retail, but breweries tend to measure their production and setup their contracts in hectoliters). Atmospheric pressure is usually measured in hectopascal because it matches so nicely with the non-SI unit millibar. Distance along the highways are shown on "hectometer poles." The use of the "hecto" prefix is more prevalent than you suggest.

Deci? Decimeter is a normal unit. Deciliter is. Granted that is about the only two dimensions but then again that's like saying that Chinese isn't spoken by a lot of people because it's spoken in only two or three countries.

Americans tend to focus enormously on the decimal character or the metric system, and the prefixes. Or that metricians are completely alien to the concept of pound and ounce (where I grew up a pound was 500 gram and an ounce was 100 gram. I'd be sent to the butcher by my mom to get a pound of ground meat, or 2 ounces of ham or something similar. Never ever would I ask for 200 grams although "1 kilo" would be the same, obviously, as two pounds). Were in reality I think the benefit is mainly in (a) engineering, as all units are expressed into each other, no conversion factors needed to translate foot-pounds per square rod to god-knows-what with some bizarro conversion factor falling out of the sky, and ( commerce, for not being bamboozled by salesmen who "forgot" to disclose they were measuring in Frankfurter pounds, Wallonian feet or Milanese Gallons or whatever.

The latter is no longer that much of a problem, since there are not that many countries using non-metric systems (Burma, Liberia and a third one I think) which eliminates the possibilities for "confusion" since it's pretty obvious what gallon one is talking about but in the time the metric system was introduced it most certainly was (hence the eagerness of most countries to switch over).

That doesn't mean there's no more confusion. The standard measure in graphic design is the pica. About everyone agrees that a pica is 1/6th of an inch, and that there are 12 inches in a foot. But what's a foot? Adobe's postscript, by sheer power of market domination, rammed the standard American "compromise inch" (25.4mm) down our throat. Thank goodness, it makes life so much easier. However, make sure your printer (not the box that spits out paper, but the company that prints your 200k leaflets) knows this, because printers traditionally base their pica's on the Johnson foot which is defined as 249/250th of a standard English (304.8mm) foot. Donald Knuth's TeX system uses that for the definition of the pica (to the best of my knowledge). Long live standard measurement systems...

[Beowolf]

a CD is about 1dm in diameter

Memorizing that fact was my very first step in going metric.

Also see this: http://xkcd.com/526/

[Rosco P. Coltrane]

Memorizing that fact was my very first step in going metric.

Also see this: http://xkcd.com/526/

That's very true. After all, for everyday life, the exact value of a measure unit is not really important. The importance lies on your appreciation of it. "Oh, I'm 1 Km away, by foot" is not the same as "Oh, I'm 1 Km away, by car".

When I started playing flight simulators I always tried to convert miles to kilometers... And I always ended faaar away from where I wanted to be. At the end, I just realized that it's not important what 10 miles is, but how much it feels.

[Kulebron]

^^

3L = Two-liter bottle.

what?!!

[Beowolf]

you'll never hear anybody talking about megagrams or exameters.

Exabyte is fairly common now in computer science papers and articles. Megagrams don't get used because 1 megagram = 1 tonne. I agree with you about "hecta". I've seen "hectare", and I have a vague memory of someone once using "hectagon"...could have been Benoit Mandelbrot back in the 80s when he was an IBM Fellow, but I'm not at all certain. But I remember pausing during the article to make sure the term meant what I thought it meant.

EDIT:

Let me see... beer is generally sold in hectoliters (not at retail, but breweries tend to measure their production and setup their contracts in hectoliters). Atmospheric pressure is usually measured in hectopascal because it matches so nicely with the non-SI unit millibar. Distance along the highways are shown on "hectometer poles." The use of the "hecto" prefix is more prevalent than you suggest.

Thanks for furthering my education, Kerbart!

Edited December 31, 2013 by Beowolf

[insylem]

I propose the following changes to the metric system:

-The base unit of mass should be the gram because base units should lack prefixes

-Remove the liter because it is redundant

-1 gram should be 1 cubic meter of water for the sake of simplicity

-Replace all dates and times with seconds since the epoch, which is the moment at which these changes are effected

-If the meter is so long as to make the metric system impractical, then so shorten it as to make it practical.

Any ideas, comments, criticisms?

-Duxwing

1: I sort of agree with this, yes, make what is now the Kilogram the gram, and thust what is now the gram would be the miligram.

2: 1 Gram = 1 Cubic Meter of water, that makes since, but that would be somewhat heavy.... Also, what tempature? Water's density changes with tempature. I think it's most dense tempature is about 277 Kelvin

3: Not sure what the Epoch is. But I think everyone should use 24 Hour, screw AM and PM. Do away with daylight savings, and set all the clocks to Zulu/GMT.

4: I have no problem with the current lengh of the meter.

5: Delete the celcius/centegrade scale. Use Kelvin as I did in item 2.

[Kerbart]

Memorizing that fact was my very first step in going metric.

Philips developed the CD and originally proposed a 1dm diameter. Sony objected because it couldn't contain one their CEO's favorite symphonies that way, and hence the 12cm cd was born.

[Galacticruler]

^^ what?!!

about 1L of that is air.

[WhiteWeasel]

Let me embed that for you:

With all respect, if there are solutions that are better, they'd already be accepted. It's not like SI is hugely conservative or has a sentimental attachment to the definition of standards; I think that the meter had it's definition changed about once every other year in the late 20th century because technology advanced.

The problem with a definition is that it needs to be:

• accurate
  
• repeatable
  
• preferably repeatable anywhere on earth

The fact that, despite it's shortcomings, the kg in Paris is still "the gold standard" tells me that as of yet nobody has come up with a way to define the kilogram in a more reliable way.

[jwenting]

However, SI units != base unit. SI used the kilogram because it relates to the other constants in a much nicer way.

Honestly I'm not seeing any motives behind those changes.

change for the sake of change...

Or someone trying to make metric useless in order to get the world to switch to imperial, which right now is useless but after these changes might be relatively better.

[Ravenchant]

-Remove the liter because it is redundant

If you did that, chances are high people are would start using some other word instead of it. Nobody is going to say "give me a cubic decimetre of milk/beer/whatever", it's just too long-winded and impractical. So in colloquial usage it's going to become, let's say, a "cube" or "decim", in which case you're back at square one. Maybe even worse off, because there are bound to be different "versions" of the word.

Otherwise, deca- is widely used in cooking (decagrams) where I'm from.

[PakledHostage]

At the risk of being accused of being pedantic, I'd like to point out that "litre" is a unit of volume (non SI, but accepted for use with SI) and "metre" is an SI unit of length. A "meter" is an instrument (i.e. voltmeter). I am not sure what a liter is other than the American spelling of litre, but as a non metric country, I don't think Americans have any right to dictate the spelling of units they don't even use. [gets down off soap box]

[Brenok]

I am not sure what a liter is other than the American spelling of litre

Probably one of these things, when misspelled:

[Kerbart]

At the risk of being accused of being pedantic, I'd like to point out that "litre" is a unit of volume (non SI, but accepted for use with SI) and "metre" is an SI unit of length. A "meter" is an instrument (i.e. voltmeter).

Given that the American National Institute of Standards and Technology (NIST) calls it a "meter," yes, you are being pedantic. "Metre" and "Litre" are the French spelling (where the metric system originated) and I guess in vogue in Canada. The non-French speaking other half of the world tends to stick to meters and liters.

I am not sure what a liter is other than the American spelling of litre, but as a non metric country, I don't think Americans have any right to dictate the spelling of units they don't even use. [gets down off soap box]

Try visiting Europe. Every country in NW Europe calls it a liter. Not sure why you think this would be a typical American thing.

Edited December 31, 2013 by Kerbart

[Charzy]

SI calls them metres and litres. As it's the organisation that creates metric units in modern times, metre is correct in the same way that colour is correct.

[PakledHostage]

Try visiting Europe. Every country in NW Europe calls it a liter. Not sure why you think this would be a typical American thing.

Can you please provide a reference? I don't see anything that gives an alternative spelling other than an "American" spelling. The NIST has produced a document which clarifies local interpretation for use with American English, but to my knowledge "American English" is only used in America. The spelling I mentioned isn't just "in vogue" in Canada, it is correct.

[Ravenchant]

Can you please provide a reference? I don't see anything that gives an alternative spelling other than an "American" spelling. The NIST has produced a document which clarifies local interpretation for use with American English, but to my knowledge "American English" is only used in America. The spelling I mentioned isn't just "in vogue" in Canada, it is correct.

It's called "liter" in our languages (NW, a large part of central Europe, possibly others). It's still "litre" when you're speaking English.

[peadar1987]

They're spelt "litre" and "metre" in the UK and Ireland as well.

Slightly off-topic, but has anyone else heard that sulphur is officially spelt "sulfur" by IUPAC, as a concession so we got to keep spelling Phosphorus properly?! It was a rumour knocking round when I was in school.

[jwenting]

Haha, i think you misunderstood me. I meant something Similar to a foot in terms of size. Larger than a centimeter but smaller than a meter. maybe a Manometer?

you're in luck. There's the decimeter.

[Arran]

From small to large the Metric Prefixes on how we call them at least in my country, i might forgot one or two..

The underlined ones are the base prefixes.

Weights

Miligram

Gram

Ons

Pond

Kilogram

Ton

Distances

NanoMeter

Milimeter

Centimeter

Decimeter

Meter

Hectometer

Kilometer

Volume

Mililiter

Centiliter

Liter

Deciliter

Hectoliter

Edited December 31, 2013 by Arran

[Duxwing]

I apologize for my incorrect suggestions, and I thank you more educated people for enlightening me.

-Duxwing

[Evans310]

^^ This clarifies the reasons behind the "prefix" nicely. If we're going to change it, let's go back to the Grav.

There are several better solutions that link the kg to unchangeable natural constants:

You can base it on the mass of atoms by defining the kg as the mass of a certain volume of pure isotope. That's what they're trying to do with the Avogadro Project.

You can link it to the speed of light and plancks constant via a watt balance.

You can also flip the definitions around and define Kg's as a function of ampere instead of the current implementation. Then you simply accelerate some mass via a current and use that to define the kg.

All of the above have trouble with the required accuracy though. But that's easily solved with better tech.

^^ This too is shown in the video Devo linked - I'm assuming that the sphere therein is in fact the one in the Avogadro project you mention.

1: I sort of agree with this, yes, make what is now the Kilogram the gram, and thust what is now the gram would be the miligram.

2: 1 Gram = 1 Cubic Meter of water, that makes since, but that would be somewhat heavy.... Also, what tempature? Water's density changes with tempature. I think it's most dense tempature is about 277 Kelvin

3: Not sure what the Epoch is. But I think everyone should use 24 Hour, screw AM and PM. Do away with daylight savings, and set all the clocks to Zulu/GMT.

4: I have no problem with the current lengh of the meter.

5: Delete the celcius/centegrade scale. Use Kelvin as I did in item 2.

^^ kelvin is the base unit for temperature in the SI. However, I don't see Celsius' scale going away any time soon due simply to its easy correlation to everyday phenomena, ie. water freezing and boiling. Then again, some people still insist on having their water freeze at thirty-two, which is even more arbitrary than 273 kelvin, so you never know.

At the risk of being accused of being pedantic, I'd like to point out that "litre" is a unit of volume (non SI, but accepted for use with SI) and "metre" is an SI unit of length. A "meter" is an instrument (i.e. voltmeter). I am not sure what a liter is other than the American spelling of litre, but as a non metric country, I don't think Americans have any right to dictate the spelling of units they don't even use. [gets down off soap box]

Given that the American National Institute of Standards and Technology (NIST) calls it a "meter," yes, you are being pedantic. "Metre" and "Litre" are the French spelling (where the metric system originated) and I guess in vogue in Canada. The non-French speaking other half of the world tends to stick to meters and liters. Try visiting Europe. Every country in NW Europe calls it a liter. Not sure why you think this would be a typical American thing.

^^ Love the use of an American governance institute to prove that an alleged American mis-spelling is correct. Like when my American friends tell me that their whole country spells it "color" so I must be wrong to put a "u" in there. You might just as well say "The American spelling is correct because the Americans say so!" I'll take the OED as my authority, thank you. But correct spelling is rather off-topic, so to get back on track:

As far as the OP goes, the Litre is not an SI unit (as has been mentionned here) but rather a unit accepted for use alongside the units of the SI. Expressed in SI terms, it would be a cubic decimetre (10 cm cubed). Other units of this type that have been retained for convenience are the minute, hour, day, degree of arc, minute of arc, second of arc, hectare (10 000 square metres or 100m X 100m), and tonne (1 000kg). Rather easier to say "litre" than "cubic decimetre", no? Just as it's much easier to navigate using degrees, minutes, and seconds of arc rather than trying to use radians.

For the folks who had questions about prefixes, there was a time when I had a dozen or so above and below memorized, but I admit that those days are behind me. So, from Wikipedia:

Prefixes are added to unit names to produce multiple and sub-multiples of the original unit. All multiples are integer powers of ten, and above a hundred or below a hundredth all are integer powers of a thousand. For example, kilo- denotes a multiple of a thousand and milli- denotes a multiple of a thousandth; hence there are one thousand millimetres to the metre and one thousand metres to the kilometre. The prefixes are never combined, and multiples of the kilogram are named as if the gram were the base unit. Thus a millionth of a metre is a micrometre, not a millimillimetre, and a millionth of a kilogram is a milligram, not a microkilogram.

Standard prefixes for the SI units of measure

Multiples Name deca- hecto- kilo- mega- giga- tera- peta- exa- zetta- yotta-

Prefix da h k M G T P E Z Y

Factor 10^1 10^2 10^3 10^6 10^9 10^12 10^15 10^18 10^21 10^24

Fractions Name deci- centi- milli- micro- nano- pico- femto- atto- zepto- yocto-

Prefix d c m μ n p f a z y

Factor 10^−1 10^−2 10^−3 10^−6 10^−9 10^−12 10^−15 10^−18 10^−21 10^−24

Back to my own thoughts, The SI is unquestionably THE best system of units for any serious scientific calculations, but there remain some day-to-day applications where legacy units are more convenient either for spoken language or actual calculation. I certainly wouldn't want to plot a course for a ship or prepare a flight plan if I had to use radians in my navigation, and it's much easier to ask the grocer for two litres of milk than two cubic decimetres.

Thanks for an interesting conversation gents, I'll be watching this one.

[codepants]

-Replace all dates and times with seconds since the epoch, which is the moment at which these changes are effected

I'm surprised nobody has mentioned this yet -- someone posted about the French Republican Calender failing, but -- how annoying would it be to have to say to someone, "See you on 1447200!" (6 PM, Jan 16, Year 1).

("Aw, man, that doesn't work for me. Can we do 1449000?" (6:30))

[dharak1]

I'm Canadian and everyone I know spells it liter and meter. Metre doesn't look right to us.

[Kulebron]

What's about that XKCD picture, where they say 2 L = 3 liter botte. Is liter an american unit equal to 1.5L? (Never heard of that one)

-Replace all dates and times with seconds since the epoch, which is the moment at which these changes are effected

-If the meter is so long as to make the metric system impractical, then so shorten it as to make it practical.

You need intermediate units anyway, because people are not machines and need rounding.

I thought of another option: make a decimal system instead of current seconds.

There are 86400 seconds in day, so the new definition of second can be just 1/100,000th, and now we get these units:

new minute (or hectasecond) = 100 seconds, or 1.440 of current minute

new quarter (or kilosecond) = 14.4 current minutes

new hour (or deciday) = 10,000 seconds or 2.4 current hours

And with this new system you don't need weird conversions with integer divisions and remainders. 10 hr 2 min 94 sec plus 17 min 56 sec will equal just 100294 + 1756 = 102050 or 10 hr 20 min 50 sec.

Unfortunately, only days and time within them can be converted this way, because yearly ciycle is not syncronized and has no common denominator with days (year lasts 365.24..... days), so essentially there should be two independent hierarchies.

Not sure if humanity will be able to switch to it, unless there's a massive catastrophy and a new civilization.