Something I kind of get a kick out of is that back some time like 1970s, the US decided to re-define the inch, as PRECISELY 2.54 cm.
Prior to this, they had metal bars that were considered to be The Definition Of An Inch. They did the same thing for meters too, the meter bar used to live in Paris...
Anyway, once scientists were able to nail the speed of light with absolute precision, they were able to define a meter as 1/C using light meters per second. And this experiment uniquely could be setup again anywhere in the world and it would re-derive a meter without any need for a "meter bar".
That's probably why the US re-defined the inch, since there was no sense sticking with an old system when a new one existed... But as a result, inches are actually legally defined in terms of meters.
<useless metrology factoid of the day>
Caleb James DeLisle
npub105…t88up
2026-09-14 11:59:18 UTC
in reply to nevent1q…lzf0
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npub10502c8jv0y27jwcwxcq9kd3ph2wg7pt8ycexf5w2fyzythe97w2s7t88upPublished at
2026-09-14 11:59:18 UTCEvent JSON
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"content": "Something I kind of get a kick out of is that back some time like 1970s, the US decided to re-define the inch, as PRECISELY 2.54 cm.\n\nPrior to this, they had metal bars that were considered to be The Definition Of An Inch. They did the same thing for meters too, the meter bar used to live in Paris...\n\nAnyway, once scientists were able to nail the speed of light with absolute precision, they were able to define a meter as 1/C using light meters per second. And this experiment uniquely could be setup again anywhere in the world and it would re-derive a meter without any need for a \"meter bar\".\n\nThat's probably why the US re-defined the inch, since there was no sense sticking with an old system when a new one existed... But as a result, inches are actually legally defined in terms of meters.\n\n\u003cuseless metrology factoid of the day\u003e",
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