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 A unit of measurement is a definite magnitude (mathematics), magnitude of a quantity, defined and adopted by convention or by law, that is used as a standard for measurement of the same kind of quantity. Any other quantity of that kind can ...

, 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 Standard ...

dialects and in

John Jamieson John Jamieson (3 March 1759 – 12 July 1838) was a Scottish minister of religion, lexicographer, philologist and antiquary. His most important work is the ''Dictionary of the Scottish Language''. Life He was born in Glasgow in March 1759 the ...

'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 Gilbert Newton Lewis (October 23 or October 25, 1875 – March 23, 1946) was an American physical chemist and a Dean of the College of Chemistry at University of California, Berkeley. Lewis was best known for his discovery of the covalent bond a ...

(1875–1946). He proposed a

unit of time A unit of time is any particular time interval, used as a standard way of measuring or expressing duration. The base unit of time in the International System of Units (SI) and by extension most of the Western world, is the second, defined as a ...

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 tera ...

to travel one centimeter in a vacuum (approximately 33.3564 picoseconds). 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 Mains electricity or utility power, power grid, domestic power, and wall power, or in some parts of Canada as hydro, is a general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is delivered to h ...

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, e ...

, a jiffy was originally the time between two ticks of the

system time In computer science and computer programming, system time represents a computer system's notion of the passage of time. In this sense, ''time'' also includes the passing of days on the calendar. System time is measured by a ''system clock'', w ...

interrupt In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, ...

. 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 The Commodore 64, also known as the C64, is an 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in the Guinness ...

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 advertisin ...

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 Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

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, which ...

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 A ...

.Entry on ''jiffy''
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 A ...

Stratus VOS Stratus VOS (Virtual Operating System) is a proprietary operating system running on Stratus Technologies fault-tolerant computer systems. VOS is available on Stratus's ftServer and Continuum platforms. VOS customers use it to support high-volume ...

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 refe ...

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

.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 ...

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 r ...

(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 science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

, 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 Edward R. Harrison (8 January 1919 – 29 January 2007) "Physics Today Obituaries: Edward R. (Ted) Harrison", William M. Irvine, PhysicsToday.org, 2007-02-23, webpage: PToday-125 was a British astronomer and cosmologist, noted for his work ...

,"The Cosmic Numbers" in ''Cosmology, The Science of the Universe'', 1981 Cambridge Press 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 ...

, which is approximately the size of a

nucleon In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number (nucleon number). Until the 1960s, nucleons were ...

. 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 A nanosecond (ns) is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, of a second, or 10 seconds. The term combines the SI prefix ''nano-'' indicating a 1 billionth submultiple of an SI unit ( ...

References

External links

FOLDOC The Free On-line Dictionary of Computing (FOLDOC) is an online, searchable, encyclopedic dictionary of computing subjects. History FOLDOC was founded in 1985 by Denis Howe and was hosted by Imperial College London. In May 2015, the site was up ...

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

Beginnings in measurement

Uses

See also

References

External links