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Experts Suggest Replacing Definition of Kilogram

Posted by Zonk on from the still-won't-be-used-in-the-states dept.

fenimor writes "The kilogram is the only one of the seven basic units of the international measurement system defined by a physical artifact rather than a natural phenomenon. International team of scientists suggest replacing the kilogram artifact -- a cylinder of platinum-iridium alloy about the size of a plum --with a definition based on one of two unchanging natural phenomena, either a quantity of light or the mass of a fixed number of atoms. They propose to adopt either one of two definitions for the kilogram by selecting a specific value for either the Planck constant or the Avogadro number."

17 of 844 comments (clear)

  1. I suggest by Anonymous Coward · · Score: 5, Funny

    They set it to 1000 grams.

    1. Re:I suggest by tibike77 · · Score: 5, Interesting

      Not only that, but it is also the only "basic measuring unit" that's not even a measuring unit, but a multiple of another one that's not considered "basic". At least in name. Kilo-gram. Get it ?

      Actually, if they happend to re-define it based on Avogadro's number, they might as well just say the GRAM is the new "basic unit" and the kilogram is just 10^3 grams.
      Why ?
      Because Avogadro's number is JUST an artifact of the definition of the (kilo)gram, not a fundamental constant - it's (been originally) defined as the number of atoms in 12 grams (or, whatever, 0.012 kilogram) of Carbon-12.
      Talk about circular references then...

      Now, basing the definition of the kilogram (might I suggest they also change that basic to gram instead of kilogram... please) on Planck's constant somehow would be a MUCH better ideea. However, the value of that constant [i.e. 6.6260693111111 * 10^-34 and so on] makes it pretty wierd to work with unless you multiply it with 9 [to get exactly 5.96346238 * 10^-33 which makes more sense somehow]. And even then it won't satisfy some people, as I'll bet you'll hear that 0.111111 and so on *9 does not equal 1 :p
      Not only that, but Planck's costant was ALSO measured "accurately" using the kilogram unit as reference.

      Ok, this actually does give me a headache.

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    2. Re:I suggest by Madcapjack · · Score: 5, Funny
      After all, an ounce of prevention is worth a pound of cure.

      I'm sorry, I don't understand. Could you rephrase that in terms of Avagrado's number, please?

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  2. does this mean by zerkon · · Score: 5, Funny

    I'm going to finally lose some weight?

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    The Answer
  3. Just wait. by jwcorder · · Score: 5, Funny

    The next thing you know they will be trying to get the US to switch from imperial units to the metric system....

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    http://jayceecorder.blogspot.com
    1. Re:Just wait. by bobscealy · · Score: 5, Funny

      I have always found it intriguing that the US both celebrates the day of its independance from the British empire and continues to use old British units of measurement.

  4. that does it by WormholeFiend · · Score: 5, Funny

    I'm going back to pounds and stones.

  5. Re:I wonder... by Anonymous+Cowpat · · Score: 5, Funny

    more importantly, what would they list it's shipping weight as?

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    FGD 135
  6. And in other news... by rollingrock · · Score: 5, Funny

    Pi is exactly equal to 3!

  7. Re:Anyone Else? by TheEternalVortex · · Score: 5, Informative

    The SI unit of mass is the kilogram, not the gram.

  8. Picture of the Kilogram Prototype by pboyum · · Score: 5, Interesting

    Picture of the International prototype kilogram:

    http://www1.bipm.org/utils/common/img/mass/prototy pe.jpg

    1. Re:Picture of the Kilogram Prototype by spectasaurus · · Score: 5, Interesting

      Better question. Why is it in 3 vacuum jars?

    2. Re:Picture of the Kilogram Prototype by ink_13 · · Score: 5, Informative
      To keep its mass from changing. You may notice the calipers for handling it in the picture, too. Stray moisture, direct sublimation into the atmosphere, anything that could possibly affect it has to be kept away,

      This is the definition of the kilogram. A kilogram is not 1L of H2O at STP (as mentioned elsewhere, pressure depends on mass), it's this little lump of metal. Changes in the mass of it are extraordinarily bad. They make copies of it for reference purposes, and then check the copies agains the original every 10 years. If there's a disagreement, the copy gets adjusted, not the original. The reference lump has actually lost about 50 micrograms in the last 100 years (and no one knows why). That's a lot (well, speaking at the level that micrograms get used at... 1 microgram = 0.000000001 kg), and the really highlights the need for an immutable reference point.

      Readers may find the pertinent Wikipedia article interesting.

  9. Pressure by XanC · · Score: 5, Insightful

    That would work fine, and I believe was the original definition. Unfortunately, pressure has a mass component, so your definition is circular.

  10. Obligatory Simpsons Metric Quote by shiafu · · Score: 5, Funny


    Lisa: Principal Skinner, how's your transportation project coming?

    Skinner: Not only are the trains now running on time, they're running on metric time! Remember this time people, 80 past 2 on April 47th. It's the dawn of a new enlightenment!

  11. Re:I wonder... by iCEBaLM · · Score: 5, Funny

    The weight formerly known as kilogram.

  12. By the way by iced_773 · · Score: 5, Funny

    How many Avogadroes are in guaca-mole?

    I guess 6.02x10^23...