Jiffy can be an informal term for any unspecified short period, as in "I will be back in a jiffy". From this, it has acquired a number of more precise applications as the name of multiple units of measurement, each used to express or measure very brief durations of time. First attested in 1780, the word's origin is unclear, though one suggestion is that it was

thieves' cant Thieves' cant (also known as thieves' argot, rogues' cant, or peddler's French) is a cant, cryptolect, or argot which was formerly used by thieves, beggars, and hustlers of various kinds in Great Britain and to a lesser extent in other English- ...

for lightning. It was common in a number of

Scots English Scottish English ( gd, Beurla Albannach) is the set of varieties of the English language spoken in Scotland. The transregional, standardised variety is called Scottish Standard English or Standard Scottish English (SSE). Scottish Standar ...

dialects and in John Jamieson's ''Etymological Dictionary of the Scottish Language'' (1808) it is suggested that it is a corruption of ' gliff' (glimpse) or 'gliffin' (glance) (compare: 'in the blink of an eye') and may ultimately derive from

Gothic Gothic or Gothics may refer to: People and languages *Goths or Gothic people, the ethnonym of a group of East Germanic tribes **Gothic language, an extinct East Germanic language spoken by the Goths **Crimean Gothic, the Gothic language spoken b ...

or Teutonic words for 'shine'. ('Gliff' or 'gliss' for 'a transient view' was also found in older English poetry as early as 1738 .)

Beginnings in measurement

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 Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...

to travel one centimeter in a vacuum (approximately 33.3564

picosecond A picosecond (abbreviated as ps) is a unit of time in the International System of Units (SI) equal to 10−12 or (one trillionth) of a second. That is one trillionth, or one millionth of one millionth of a second, or 0.000 000 000&nbs ...

s). It has since been redefined for different measurements depending on the field of study.

Uses

electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...

, a jiffy is the period of an

alternating current Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in whic ...

power cycle, 1/60 or 1/50 of a second in most mains power supplies. In

computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, ...

, a jiffy was originally the time between two ticks of the system timer interrupt. It is not an absolute time interval unit, since its duration depends on the clock interrupt frequency of the particular hardware platform. Early microcomputer systems such as the Commodore 64 and many game consoles (which use

television Television, sometimes shortened to TV, is a telecommunication medium for transmitting moving images and sound. The term can refer to a television set, or the medium of television transmission. Television is a mass medium for advertising, ...

s as a display device) commonly synchronize the system interrupt timer with the vertical frequency of the local television standard, either 59.94 Hz with

NTSC The first American standard for analog television broadcast was developed by National Television System Committee (NTSC)National Television System Committee (1951–1953), Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplement ...

systems, or 50.0 Hz with most PAL systems. Jiffy values for various

Linux Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, whi ...

versions and platforms have typically varied between about 1 ms and 10 ms, with 10 ms reported as an increasingly common standard in the

Jargon File The Jargon File is a glossary and usage dictionary of slang used by computer programmers. The original Jargon File was a collection of terms from technical cultures such as the MIT AI Lab, the Stanford AI Lab (SAIL) and others of the old ARPANET ...

.Entry on ''jiffy''
in The Jargon File Stratus VOS uses a jiffy of 1/65,536 second to express date and time (number of jiffies elapsed since . Stratus also defines the microJiffy, being 1/65,536 of a regular Jiffy. The term "jiffy" is sometimes used in

computer animation Computer animation is the process used for digitally generating animations. The more general term computer-generated imagery (CGI) encompasses both static scenes ( still images) and dynamic images ( moving images), while computer animation re ...

as a method of defining playback rate, with the delay interval between individual frames specified in 1/100 of a second (10 ms) jiffies, particularly in

Autodesk Animator Autodesk Animator is a 2D computer animation and painting program published in 1989 for MS-DOS. It was considered groundbreaking when initially released.

.FLI The FLIC file formats most known in the extension .FLI and .FLC, used to store animation files. It is similar to animated GIF. The FLIC animation format was originally developed by Autodesk for use with Autodesk Animator (FLI) and Autodesk Anima ...

sequences (one global frame frequency setting) and animated

Compuserve CompuServe (CompuServe Information Service, also known by its initialism CIS) was an American online service provider, the first major commercial one in the world – described in 1994 as "the oldest of the Big Three information services (the oth ...

.GIF The Graphics Interchange Format (GIF; or , see pronunciation) is a bitmap image format that was developed by a team at the online services provider CompuServe led by American computer scientist Steve Wilhite and released on 15 June 1987 ...

images (each frame having an individually defined display time measured in 1/100 s). The

speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit fo ...

in a vacuum provides a convenient universal relationship between distance and time, so in

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which ...

(particularly in

quantum physics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, qua ...

) and often in

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...

, a jiffy is defined as the time taken for light to travel some specified distance. In

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...

and quantum physics a jiffy is, as defined by Edward R. Harrison,"The Cosmic Numbers" in ''Cosmology, The Science of the Universe'', 1981

Cambridge Press Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer. Cambridge University Press i ...

the time it takes for light to travel one

fermi Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" and t ...

, which is approximately the size of a nucleon. One fermi is 10⁻¹⁵ m, so a jiffy is about 3 × 10⁻²⁴ seconds. It has also more informally been defined as "one light-foot", which is equal to approximately one nanosecond.

References

External links

* FOLDOC {{Time measurement and standards Jiffy Jiffy#Use in computing Jiffy#Use in computing

Beginnings in measurement

Uses

See also

References

External links