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posted by janrinok on Tuesday November 29 2016, @03:32AM   Printer-friendly
from the getting-their-measure dept.

Fundamental constants are physical quantities that are universal in nature.
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According to a recent evaluation and update of the values of the fundamental constants by researchers at the National Institute of Standards and Technology (NIST), the uncertainties in measurements of the constants have now been reduced to such exceedingly low levels that all of the SI units can now be linked to them.
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The latest update of the values of the fundamental constants was authored by NIST's Peter Mohr, David Newell and Barry Taylor, who lead the international Task Group on Fundamental Constants of the Committee on Data for Science and Technology (CODATA). This task group updates the values every four years. The new quantities represent the latest comprehensive adjustment of values of the constants. In the summer of 2017, the task group will perform a special update to produce the final values for four fundamental constants to be adopted in the fall of 2018 by an international body known as the General Conference on Weights and Measures (Conférence Générale des Poids et Mesures, or CGPM).
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Examples of fundamental constants range from the magnitude of the elementary charge of a single electron or proton to the extraordinary number of particles in one mole of a substance, described by the Avogadro constant. Another example is the Planck constant, a quantity at the heart of quantum physics that will be used to redefine the kilogram as an invariant property of nature instead of a standard platinum-iridium cylinder.

The evaluation and update reduce the uncertainties in both the Planck and Avogadro constants by almost four times compared to the previous evaluation, to just 12 parts per billion. These uncertainties decreased by reconciling measurements in different "watt-balance" devices around the world and new highly accurate X-ray measurements of a softball-sized sphere of silicon that is a nearly perfect crystal and is made almost entirely of the same isotope of silicon (99.9995 percent silicon-28). The update reduces the relative uncertainty by almost two times, to 0.6 parts per million, for the Boltzmann constant, which can be used to determine the amount of energy in a gas at a certain temperature.

Related reporting.


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  • (Score: 0) by Anonymous Coward on Tuesday November 29 2016, @04:45AM

    by Anonymous Coward on Tuesday November 29 2016, @04:45AM (#434349)

    Who says that the uncertainty can be eliminated? Refined, refined, sure. But that's the base chaos that cosmos is built upon. Cosmos is just one possibility in the endless chaos. A stable phenomenon with locality and entropy. Something regular, like a glider in the game of life. Unexpected, yet it /works/, and it's predictable.

  • (Score: 1, Insightful) by Anonymous Coward on Tuesday November 29 2016, @09:59AM

    by Anonymous Coward on Tuesday November 29 2016, @09:59AM (#434402)

    Who says that the uncertainty can be eliminated?

    Nobody. But it may be reduced enough that they can be used to replace the current definitions of the SI base units without losing any accuracy.

  • (Score: 3, Interesting) by WalksOnDirt on Tuesday November 29 2016, @10:30AM

    by WalksOnDirt (5854) on Tuesday November 29 2016, @10:30AM (#434405) Journal

    Avogadro's number should be whole. If it necessary to make it fractional to match the other constants we're doing something wrong.

    • (Score: 2) by FatPhil on Tuesday November 29 2016, @03:34PM

      by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Tuesday November 29 2016, @03:34PM (#434499) Homepage
      The other constants should be scaleable such that we end up with Avagadro's number at 1, that being the fundamental quantity by which I want to count things.
      --
      Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
    • (Score: 1, Informative) by Anonymous Coward on Tuesday November 29 2016, @08:04PM

      by Anonymous Coward on Tuesday November 29 2016, @08:04PM (#434651)

      how the hell is this interesting?
      Avogadro's number has 23 digits.
      We can't measure it with 23 digit precision.

      • (Score: 0) by Anonymous Coward on Friday December 02 2016, @06:33AM

        by Anonymous Coward on Friday December 02 2016, @06:33AM (#435834)

        I think the point is rather that it should be an integer value when we reach 23 digits of precision.