[time-nuts] Dead CBT

Tom Van Baak tvb at LeapSecond.com
Sat Aug 27 14:45:58 UTC 2011

>> Haven't figured  the radioactive or not issue.
>> Regards and  thanks.
>> Paul


The isotope of cesium used in atomic clocks is Cs133, which is
a naturally occurring, non-radioactive (stable) isotope.

You're probably thinking of the other isotope, Cs137, which is
famous for being an unwelcome airborne radioactive by-product
of reactor accidents. In fact, there are still unnatural levels of
this isotope in the atmosphere due to fission weapons testing
during the cold war.

But again, the kind of cesium in vitamins, in your body, and in
atomic clocks is the safe, stable, Cs133 variety. See also:

I can't say the same for carbon (C14) or potassium (K40). See


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