An observer is one who engages in

observation Observation is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data via the use of scientific instruments. The ...

or in watching an experiment. Observer may also refer to:

Computer science and information theory

* In

information theory Information theory is the scientific study of the quantification (science), quantification, computer data storage, storage, and telecommunication, communication of information. The field was originally established by the works of Harry Nyquist a ...

, any system which receives information from an object *

State observer In control theory, a state observer or state estimator is a system that provides an estimate of the internal state of a given real system, from measurements of the input and output of the real system. It is typically computer-implemented, and pr ...

in control theory, a system that models a real system in order to provide an estimate of its internal state * Observer pattern, a design pattern used in computer programming

Fiction

* ''Observer'' (novel), a 2023 science fiction novel by Robert Lanza and Nancy Kress * ''Observer'' (video game), a cyberpunk horror video game * Observer (''Mystery Science Theater 3000''), a fictional television character * Observers, beings in the television show ''Fringe''

Military

* Air observer, an aircrew member * Artillery observer, a front line personnel who directs fire discipline for artillery strikes * Royal Observer Corps, a civil defence organisation, originally tasked with reporting enemy aircraft * Observer, a non-participating officer, or umpire, tasked with observing the actions of soldiers during a field training or military exercise

Music

* "Observer", a song by Gary Numan on his album '' The Pleasure Principle'' * "The Observer", a track from The Flaming Lips' 1999 album '' The Soft Bulletin'' * The Observers, an alternative name for reggae session band Soul Syndicate * Niney the Observer (born 1951), Jamaican record producer and singer

Publications

Observer.com ''The New York Observer'' was a weekly newspaper printed from 1987 to 2016, when it ceased print publication and became the online-only newspaper ''Observer''. The media site focuses on culture, real estate, media, politics and the entertainmen ...

, an online-only version of the weekly newspaper ''The New York Observer'' * ''Sunday Observer'' (Sri Lanka), a weekly newspaper * ''Observer'' (APS), a member magazine of Association for Psychological Science * ''The Observer'' (disambiguation), any of various periodicals

Science

Observer (general relativity) General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. G ...

* Observer (meteorological) * Observer (physics) * Observer (quantum physics) * Observer (special relativity) * Observational astronomy

Other uses

* Observer status, granted by an organization to allow a non-member limited participation * An election observer, one who assists in election monitoring * A game official sometimes used in the sport

Ultimate Ultimate or Ultimates may refer to: Arts, entertainment, and media Music Albums * ''Ultimate'' (Jolin Tsai album) * ''Ultimate'' (Pet Shop Boys album) *''Ultimate!'', an album by The Yardbirds *''The Ultimate (Bryan Adams Album)'', a compilatio ...

* The Observer type in the Enneagram of Personality model * Donald Alaster Macdonald (1859–1932), Australian journalist who wrote under the pseudonym 'Observer'