• Pipoca@lemmy.world
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    1 year ago

    Kinda sorta not really.

    One problem with units is defining them precisely.

    For example, a meter is ostensibly “one ten-millionth of the distance from the equator to the North Pole along a great circle”. That’s not exactly precisely defined because the earth isn’t a perfect sphere.

    So currently, a meter is defined to be the distance light travels in a vacuum in 9192631770 / 299,792,458 hyperfine structure transitions of caesium-133.

    Rather than doing the same sort of thing with updating the standard definition of a foot or pound, the US just piggybacked off the work precisely defining metric units and defined imperial in terms of metric.

    So now a foot is officially the precise distance light travels in some number of hyperfine structure transitions of caesium-133, and the US government didn’t need to do a thing.