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Kilo prototype mysteriously loses weight

  1. Sep 12, 2007 #1

    ZapperZ

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    The standard kilogram is now mysteriously lesser, but about 50 micrograms!

    Look out everyone. We are all heavier! So much for me trying to lose weight!

    Zz.
     
  2. jcsd
  3. Sep 12, 2007 #2

    Ivan Seeking

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    Wow! That is odd. Very slow radioactive decay?
     
    Last edited: Sep 12, 2007
  4. Sep 12, 2007 #3

    ZapperZ

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    I would vote on vacuum fluctuation!

    :)

    Zz.
     
  5. Sep 12, 2007 #4
    Local effects of Hubble flow.
     
  6. Sep 12, 2007 #5

    turbo

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    Iridium has two stable (?) isotopes 191Ir and 193Ir. Suppose that there was a small admixture of unstable isotopes in the kilo prototype?
     
  7. Sep 12, 2007 #6
    How about innacurate measurements 118 years ago?
     
  8. Sep 12, 2007 #7
    Thats really cool. Although I don't understand half of the theories you guys put up, its still cool.
     
  9. Sep 12, 2007 #8

    turbo

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    The prototype is losing mass with respect to later copies (and they are compared periodically), so perhaps 193Ir can very slowly decay to 191Ir at a rate that must be measured in decades or centuries.
     
  10. Sep 12, 2007 #9
    I would vote on vacuum fluctuation!

    I second this!
     
  11. Sep 12, 2007 #10

    Moonbear

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    So, out of curiousity, how do they know the standard is the one losing weight, and that the problem isn't that the ones kept under less stringent conditions aren't gaining weight from things like fingerprints and dust?
     
  12. Sep 12, 2007 #11
    I agree with Moonbear, but kind of find it hard to believe that carelessness like that would be overlooked. I think it could be some sort of extremely slow radioactive decay.
     
  13. Sep 12, 2007 #12

    turbo

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    Maybe not a radioactive decay, but a spallation process in which the heavier isotope is hit by high-energy particles, and goes to 192Ir, which IS radioactively unstable and decays to 191Ir.
     
  14. Sep 12, 2007 #13

    I say a prankster went around touching all the replicas. This is a case for Gil Grissom. :biggrin:
     
  15. Sep 13, 2007 #14
  16. Sep 13, 2007 #15

    ZapperZ

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    That's because the article didn't mention any. But I bet it wasn't Atkins.

    Zz.
     
  17. Sep 13, 2007 #16
    I suspect the copies have all simply picked up varying amounts of mass by contact with other things during transportation to and from the Institute.
     
  18. Sep 13, 2007 #17
    So, just picking one up would increase the weight?

    Isn't it possible that during transport, the bumpy bumping bumps might have transfered something from/to the base it sits on?
     
  19. Sep 13, 2007 #18

    Astronuc

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    5 parts per 100 million? I have to wonder about the uncertainty in the measuring system. Maybe someone cleaned it.
     
  20. Sep 13, 2007 #19
    What to they do when they find such a discrepency. Do they lop off 50 micrograms of the material from the heavy ones? Do they just add a fudge factor when they use the heavy ones? To what use do you put a lump of metal that is a whopping 50 million picograms more than a kilogram?
     
  21. Sep 13, 2007 #20

    ZapperZ

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    Actually, 50 micrograms is HUGE because we can actually detect a change in mass when just one monolayer of atoms have been formed. Quartz crystal thickness monitor that is commonly used in monitoring thin film deposition can measure such change.

    Zz.
     
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