4 ms·
No, that's how the metre is defined. The second is defined by the transition between two hyperfine states of cesium 133 (9,192,631,770 'oscillations').
by stan_rogers 6y ago
No, that's how the metre is defined. The second is defined by the transition between two hyperfine states of cesium 133 (9,192,631,770 'oscillations').