The earliest technical usage for jiffy was defined by Gilbert Newton Lewis (1875–1946). He proposed a unit of time called the “jiffy” which was equal to the time it takes light to travel one centimeter in a vacuum (approximately 33.3564 picoseconds). It has since be redefined for different measurements depending on the field of study. 

Source:https://en.wikipedia.org/wiki/Jiffy_(time)  

Source: https://allthatsinteresting.com/interesting-facts-about-the-world#84