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Paper sizes explained
Have you ever wondered why A4 is the way it is?
Posted 10 years ago by matthewG in category: interesting
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(guest) - 10 years ago [ Reply ]
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the meter is not defined through the size of the earth anymore (like it used to be), but it is defined as the length that light travels within 1/299 792 458 seconds in vacuum which is even more fundamental and replicable at any place in the universe.

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(guest) - 10 years ago [ Reply ]
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but then how do you define the duration of one second? ;p

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heftygrain - 10 years ago
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  Originally defined as "1/86,400 of a mean solar day", the current definition is "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom." x-) 

spydyrman - 10 years ago [ Reply ]
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He spent half of the video trying to be funny, mocking US paper sizes. I wish he would have just stuck to explaining paper sizes. Almost made it to an upvote.

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