As many of you know, the second is defined as
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
This decision was adopted in 1967 by International Committee of Weights and Measures. In that time, computers were in a very low stage, not being able to do much things.
Nowadays, with such technology that we own it's quite easy and very precised to measure those periods of radiations of an atom.
My question is, how they were able to measure those 9,192,631,770 oscillations with a low amount of technology and how they did it? Which processes they've been using?
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