“The second […] is defined by taking the fixed numerical value of the caesium frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1.[1]”
Those definitions are picked to be as immutable, unambiguous and easily replicated in a lab as possible, but have nothing to do why a second is defined like that.
But did you know that if you tie exactly 1m of string to some heavy object, it will swing once per second?
“The second […] is defined by taking the fixed numerical value of the caesium frequency, ΔνCs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s−1.[1]”
Those definitions are picked to be as immutable, unambiguous and easily replicated in a lab as possible, but have nothing to do why a second is defined like that.
But did you know that if you tie exactly 1m of string to some heavy object, it will swing once per second?