idioms: in a jiffy

Jiffy has been used informally since at least 1785 to mean a very short time. No one knows where the word originally came from. Some sources suggest it may have been a word for "lightning" in the slang used by thieves at the time—so doing something “in a jiffy” was equivalent to being “as fast as lightning.”

Scientific use

Despite its lowly beginnings, jiffy gained a certain status in the 20th century as a unit of measurement in the scientific world.

This trend started with American chemist Gilbert Newton Lewis in the first half of the 20th century. He suggested using the term jiffy to represent the time it takes for light to travel one centimetre—0.000000000033 seconds, or 33 trillionths of a second.

Since then, various sciences have adopted the jiffy, with differing definitions:

Electronics—the time between alternating current cycles. That’s 0.017 seconds (1/60 second) in North America and 0.02 seconds (1/50 second) in Europe.
Computing—the time it takes for one tick of the system timer interrupt. Depending on the operating system, this time can vary from 0.001 seconds (1/1000 second) to 0.01 seconds (1/100 second).
Astrophysics—the time it takes for light to travel one fermi (the diameter of a nucleon, or 1 quadrillionth of a metre). That’s 0.000000000000000000000003 seconds.
Quantum physics—the time it takes light to travel a Planck length (the smallest measurable distance). That’s a currently unmeasurable time of 0.000000000000000000000000000000000000000000054 seconds.

As you can see, a jiffy in scientific circles represents a very small unit of time indeed — the merest fraction of a second! Scientifically speaking, you can’t do anything in a jiffy, no matter how fast you are!