The Kilogram Could Soon be Redefined. But You Won’t Notice

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I’ve always been a keen observer of weights and measures, so this interested me. Digital Trends writes: “On Friday, November 16, a 129-year-old tradition will likely come to an end. Nearly all the world’s weighted measurements have relied on a single standard since 1889 — the International Prototype Kilogram (IPK), a block of metal made of platinum and iridium locked in a subterranean vault in Paris.

“Rather than defined by a block of metal, weights will be expressed in terms of the Planck constant (h). The stated goal is to shift the standard toward a more reliable form, one that won’t be damaged or corrupted by environmental factors that cause it to slightly and inexplicably lose weight.”

Check It Out: The Kilogram Could Soon be Redefined. But You Won’t Notice

The Kilogram Could Soon be Redefined. But You Won’t Notice

3 Comments Add a comment

  1. wab95

    @JonGI:

    You were taught correctly. People frequently conflate ‘mass’ and ‘weight’ – the force of gravity acting upon mass – and use them interchangeably. As we continue our migration from being a single planetary species to an interplanetary species, that synonymity will be scrapped as a matter of exigency. Our survival will depend on precise definitions and measurements calibrated to different environments, some of them dynamic, and use cases.

    John:

    Moving away from physical and mechanical representations of phenomena to universal constants is a huge step forward and, to be sure, an under-appreciated paradigm shift that will have important but equally under-appreciated effects on not only science but everyday life. I find this not only hugely exciting (perhaps a sad commentary on my quality of life) but an indicator of our maturation as a species as we come to exploit universal principles and constants in practical everyday use.

    I’ll make a prediction that none of us will live to see (which is great, since I won’t need to pay up should I be proved wrong); as we move further into becoming a space faring and multi-planetary species, indeed as we learn more about how to manipulate the fabric of spacetime to our benefit, we will move away from terrestrial-centric (earth-centric) definitions and measures to universal constants derived from quantum theory.

    For now, I’ll settle for a safe landing for InSight on the surface of Mars on Monday, 26 November 2018, at 19:53 UTC.

  2. JonGl

    But I thought the kilogram was supposed to be an expression of mass (not gravity dependent), not weight (gravity dependent). Will this new standard also be a measurement of mass?

    Also, I recall, as a young person, being taught that a cubic centimeter of water at a certain equaled the mass of one gram, and that was the basis of the kilogram… maybe I was taught wrong? or maybe I’m remembering wrong. or maybe it wasn’t the “standard”, or was just how they sort of arrived at it. My googling is revealing nothing specific, sadly.

    • John Martellaro

      JonGL. The kilogram is still defined in terms of mass. That hasn’t changed. But like the meter, which was originally defined as one ten millionth of the distance from the equator to the pole, it eventually was defined in terms of other physical constants. The same goes for the redefined kilogram, 1,000 cc water -> Platinum-iridium cylinder in Paris -> well known physical constants.

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