That a "jiffy" is an actual scientific unit of time?

Yes! A “jiffy” is not just a casual word people use for “a very short time,” but it is also an actual scientific unit of time. The meaning of a jiffy changes depending on the scientific field, but in all cases, it represents an extremely tiny amount of time.

In physics, especially in electronics and computing, a jiffy is often defined as the time between alternating current (AC) power cycles. For example, in the United States, where the power supply frequency is 60 hertz, one jiffy is 1/60 of a second. In many other countries with 50 hertz power, a jiffy is 1/50 of a second. This definition was commonly used by computer scientists in the early days of programming when timing processes were measured in such short intervals.

In quantum physics, however, the term jiffy can mean something even smaller. The American physicist Edward R. Harrison proposed that a jiffy could be defined as the time it takes for light to travel one femtometer (that is, $10^{-15}$ meters). Since the speed of light is approximately $3 \times 10^8$ meters per second, this definition makes a jiffy equal to about $3 \times 10^{-24}$ seconds. That is unimaginably fast!

Interestingly, in computer science, a jiffy can also mean the length of one tick of the system timer interrupt. This value differs across operating systems but is often around 10 milliseconds (0.01 seconds). Programmers sometimes use “jiffy” to describe waiting times in their code.

So, depending on the context, a jiffy can mean:

• 1/50 or 1/60 of a second (electronics/AC cycles),

• $3 \times 10^{-24}$ seconds (physics definition),

• Around 0.01 seconds (computer science).

In everyday language, people say “I’ll be back in a jiffy!” to mean “a very short time.” While that is still true, the scientific definitions show that a jiffy is indeed a real, measurable unit of time.

In conclusion, the word “jiffy” may sound funny or casual, but scientists and engineers have used it seriously to measure very short time intervals. Whether it’s fractions of a second or unimaginably tiny moments related to the speed of light, the jiffy proves that even the smallest slices of time can have precise meanings in science.