[HN Gopher] Why is a second equal to the duration of 9,192,631,7...
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       Why is a second equal to the duration of 9,192,631,770 of
       radiations?
        
       Author : modinfo
       Score  : 12 points
       Date   : 2023-10-28 18:13 UTC (4 hours ago)
        
 (HTM) web link (physics.stackexchange.com)
 (TXT) w3m dump (physics.stackexchange.com)
        
       | tialaramex wrote:
       | The choice to define SI such that the constants have known
       | specific values, with the result that the exact meaning of the
       | units is the thing our metrication discovers not the values of
       | those constants - is a really clever trick.
       | 
       | This completes the work of making SI truly universal. Once upon a
       | time all of SI was defined in terms of prototypes, available only
       | locally. In the case of objects like the kilogram and the metre,
       | these were literally prototype physical objects, in some other
       | cases what we measured was the planet we lived on, which is at
       | least available in theory to all its occupants, although not much
       | use if you're in Andromeda. While measuring the second according
       | to its current definition is a bit trickier than estimating its
       | first definition (in terms of a solar day) it's actually possible
       | anywhere in principle.
        
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       (page generated 2023-10-28 23:00 UTC)