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"The length of the path travelled by light in vacuum during a time interval of 1/299792458 of a second, where the second is defined by a hyperfine transition frequency of caesium."
This is the actual definition, but it's also pretty weird.
And here I thought it was that sick of metal in the wall in France when it is 21 degrees C
It was defined as
one ten-millionth of the shortest distance from the North Pole to the equator passing through Paris.
The stick of metal in Paris is just so people don't have to do measure the distance between the north pole and the equator each time they want to check their measuring tool.
They redefined it a few years ago to base all units on some objectively measurable natural constant. Because that stick of metal might still decay or warp or something and you don't always want to travel to France when you want to know the length of a meter. Much easier to measure the atoms and light you have on hand.
Updating the kilogram standard took them forever because you need really reliable force measurement instruments and very precise calibration
How many midi-chlorians does 1 meter have tho...
Found the vampire.
Hey, just because I am Australian doesn't mean I am a crime of nature. That is just our animals.
Australia, where even the animals are criminals.