space war
''Space War'' is a video game cartridge released by Atari, Inc. in 1978 for the Atari Video Computer System (renamed to the Atari 2600 in 1982). The game is a version of '' Spacewar!'', the 1962 computer game by Steve Russell. It was released ...
between combatants from different
planetary system
A planetary system is a set of gravitationally
In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interacti ...
science fiction
Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel unive ...
, especially in the
space opera
Space opera is a subgenre of science fiction that emphasizes space warfare, with use of melodramatic, risk-taking space adventures, relationships, and chivalric romance. Set mainly or entirely in outer space, it features technological and soci ...
subgenre. In contrast, the term ''intergalactic war'' refers to war between combatants from different
galaxies
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...
, and ''interplanetary war'' refers to war between combatants from different
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
s of the same planetary system.
Likelihood
Michael H. Hart
Michael H. Hart (born April 27, 1932), is an American astrophysicist, author, amateur historian, researcher, and white separatist/white nationalist. Since 1978, he has published five books, most notably of the best-selling work, '' The 100: A Ra ...
argued that if humans ever spread to other planetary systems, the actual likelihood of interstellar war would be low due to the immense distances (and hence travel times involved)—interstellar war would require a vastly greater investment of time and resources than present-day intraplanetary wars involve. By contrast, Robert Freitas argued that the energy expenditure required for interstellar war would be trivial from the viewpoint of a Type II or Type III civilisation on the Kardashev scale.
Interstellar war in fiction
The earliest fictional references appear to deal with interplanetary, not interstellar war (e.g.
outer planets
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
by means of technologies utilising the laws of physics as currently understood. However, now that the other planets of the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
are believed to be devoid of intelligent life, sci-fi writers generally posit some form of
faster-than-light drive
Faster-than-light (also FTL, superluminal or supercausal) travel and communication are the conjectural propagation of matter or information faster than the speed of light (). The special theory of relativity implies that only particles with zero ...
Space warfare
Space warfare is hypothetical combat in which one or more belligerents are situated in outer space. The scope of space warfare therefore includes ''ground-to-space warfare'', such as attacking satellites from the Earth; ''space-to-space warfa ...
References
* {{Cite journal , last=Korhonen , first=Janne M. , date=2013 , title=MAD with aliens? Interstellar deterrence and its implications , url=https://arxiv.org/abs/1302.0606 , journal=
Acta Astronautica
''Acta Astronautica'' is a monthly peer-reviewed scientific journal covering all fields of physical, engineering, life, and social sciences related to the peaceful scientific exploration of space. The journal is widely known as one of the top aer ...