[time-nuts] Why 9,192,631,770 ??

J. Forster jfor at quikus.com
Wed May 9 00:35:45 UTC 2012


Because the length of the second is essentially arbitrary. There is
nothing 'fundamental' or 'universal' about it. It is essentially derived
from the average rotational period of the earth, which is a random number.

When the number of cycles was defined, they picked the nearest whole
number to an integral number of cycles, and re-defined the second to be
that.

-John

================





> I've gotten myself confused ...easily done when you're not a physicist
> (just
> a lowly EE.)   :-)
>
> I am studying cesium clock design and trying to learn how these complex
> instruments actually work. I seem to be getting the understanding on the
> 'workings' of the clock ...the tube, the counters, disciplining, etc.
>
> But I have a higher level question I need help understanding. (Remember
> ...not a physicist here.)
>
> Who decided 9,192,631,770 cycles of 'light' constitute one second?  I
> don't
> mean who the person was, or which company or institution or when.
>
> I ask, why not ...771 cycles ...or ...669 cycles????
>
> What I need is the understanding of what a 'second' is defined to be
> without
> having the definition of a 'second' to begin with.
>
> This seems all so recursive to me.
>
> Thank you.  (remember - - you guys said there were no dumb questions - -
> or
> at least, we should ask them anyway.)
>
>
>
>
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