hiccup

eflex involving opening the mouth wide, taking a deep breath, and then exhaling. It is often associated with tiredness, boredom, or the need to increase alertness. Why Do We Yawn? While the exact purpose of y

efined based on atomic physics, specifically: > The duration of 9,192,631,770 periods of radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom. This