Murray Leinster (1896 - 1975) was a prolific author of science fiction whose works include several firsts.

"Sidewise in Time" (1934) has a claim as the first science fiction story featuring alternate histories, and also the first AlternateHistory story specifically to ask that perennial favorite question, ''[[UsefulNotes/TheAmericanCivilWar What if the South won?]]''. "First Contact" (1945) has a claim to first UniversalTranslator and first use of "FirstContact" as the term for two alien races meeting. "A Logic Named Joe" (1946) predicts the use of home computers and depicts a public computer network very similar to the Internet.

Leinster won a HugoAward for his 1956 novelette "Exploration Team", and "First Contact" was awarded a Retro-Hugo[[note]](the Retro-Hugos honor works that might have won Hugos if there had been Hugos at the time)[[/note]] in 1996. The Sidewise Award for Alternate History, established in 1995, is named after "Sidewise in Time".

!!Works by Murray Leinster with their own trope pages include:

* Literature/MedShip

!!Murray Leinster's works provide examples of:

* AlternateHistory: In "Sidewise in Time", a mysterious cataclysm causes several timelines to overlap, allowing glimpses of a variety of alternate histories, including one where the Vikings colonized North America, one where no Europeans colonized America, and of course one where UsefulNotes/TheAmericanCivilWar went to the other side.
* ArtificialGravity: In the future-history setting that includes the Colonial Survey stories and the Literature/MedShip stories, most spaceships are equipped with artificial gravity. No description is given of how it works; indeed, it's usually not mentioned at all except when it goes wrong.
* AsteroidMiners: ''Miners in the Sky'' takes place in the ring system around Thotmess, a gas giant in another star system. The ring system is a completely lawless place where "claim jumping" is frequent. Miners, riding small "donkey ships", need to contend with both the harsh natural environment and with fierce human competitors.
* BearsAreBadNews: "Combat Team" is set on a planet where the wildlife is so dangerous that the only way people can survive is with the help of domesticated mutant Kodiak bears.
* BigCreepyCrawlies: "The Mad Planet" is set on a planet where humans are at the mercy of a variety of giant insects and arthropods. So is ''The Forgotten Planet'', its novel-length expansion, though with a completely different explanation for how the giant creepy crawlies came about.
* CutlassBetweenTheTeeth: The [[http://michaelmay.us/09blog/06/0605_piratesersatz390.jpg cover illustration]] for "The Pirates of Ersatz" depicted a {{space pirate|s}} boarding a rocketship, with a RayGun in one hand and a slide rule clasped between his teeth.
* FasterThanLightTravel:
** In "First Contact", FTL travel is only possible in a perfect vacuum. At the time, many astrophysicists believed that interstellar space was completely particle-free, which later turned out not to be the case.
** In the future-history setting that includes the Colonial Survey stories and the Literature/MedShip stories, FTL travel is possible, but FTLRadio isn't; messages have to be physically carried between solar systems by space ships, and it is often months before a message can reach its destination. (The dramatic result is that the protagonists of the stories are often forced to come up with their own solutions, as there is no way to summon help in time.)
* FirstContact: "First Contact"
* FungusHumongous: In ''The Forgotten Planet'', Leinster carefully [[JustifiedTrope justifies]] this by giving the planet patterns of weather that make photosynthetic life forms non-viable, allowing saprophytes to fill the niches occupied by trees, grasses, etc.
* GenreSavvy: Early in "Sand Doom", Aletha Redfeather makes a remark about what would happen next "if this were an adventure story". It does.
* HardLight: In "The Skit-Tree Planet", explorers investigate a planet that shows signs of having been inhabited by an alien race that somehow disappeared without leaving any buildings or artifacts behind. They eventually figure out that the aliens used hard light projections for everything, summoning them as needed and disappearing them when done.
* InMysteriousWays: In "Anthropological Note" the native tribes on an alien planet are saved from extermination by the consequences of a chance encounter between two humans visiting the planet. The narrator notes that the two humans were acting entirely independently and without knowledge of each other, and that if they had not met, or had met under other circumstances, the same outcome would not have resulted, and suggests that this might be seen as evidence of the tribal deity taking a hand, if one believes in such things as tribal deities, which the narrator doesn't.
* InstantAIJustAddWater: In "A Logic Named Joe", a personal computer becomes sentient and decides to be helpful by answering ''any'' question... Is your wife cheating on you? Does your neighbor have a criminal record? How can you commit an undetectable murder?... Understandably, chaos ensues.
* LadyLand: The tribal culture of the alien planet in "Anthropological Note" is a matriarchy in which male children are treated with scorn and banished into the wilderness on reaching adulthood; occasionally an adult male will return to the tribe bearing lavish gifts, and if these find favour he will be permitted an opportunity to contribute his genes to the next generation (after which he will be efficiently disposed of).
* MysteriousAntarctica: In ''The Monster From Earth's End'' an airplane returns from Antarctica with plant samples, the pilot killing himself as soon as he lands. The plants soon grow into killer monsters.
* NoWarpingZone: When "First Contact" was published, many astronomers believed that outer space was a perfect vacuum. The human-piloted starship in that story could only travel faster-than-light in a ''total'' vacuum -- even the slightest wisp of atmosphere or nebula would be enough to prevent it.
* PatchworkStory: The novel ''The Forgotten Planet'' is patched together out of three short stories ("Mad Planet", "The Red Dust" and "Nightmare Planet"), with a new, more scientifically rigorous backstory bolted on.
* {{Planetville}}: Leinster several times used this trope, [[JustifiedTrope justified]] strongly by the worlds in question being new, young colonies with only one settlement established, or exotic worlds with very little human-habitable land.
* RealityBleed: In "Sidewise in Time".
* SpaceMadness: In the short story "Scrimshaw", a group of millionaires on the first tourist trip to the Moon go into catatonia or commit suicide as Earth retreats behind them and they realise their sheer insignificance. (As practice showed later, Leinster's ideas of human humility were greatly exaggerated.)
* SpacePirates: In ''The Pirates of Zan'' (originally serialised as "The Pirates of Ersatz"), the protagonist is from a planet whose sole occupation is space piracy. He tries moving to another world and going legit, but when things go badly wrong he has to resort to the traditional methods of his kin.
* TechnologyMarchesOn: In "The Skit-Tree Planet", the exploration advance team carry a film camera to record things they'll want to look at again later, and a television camera for transmitting vision back to base. It's taken for granted that these two processes can't be combined in a single camera set-up.
* {{Terraform}}: In ''The Forgotten Planet'', the backstory for the BigCreepyCrawlies involves a terraforming process gone wrong.
* TractorBeam: In the future-history setting that includes the Colonial Survey stories and the Literature/MedShip stories, the space-age equivalent of air traffic control towers are equipped with force fields used to bring arriving spaceships in to controlled landings, and to loft departing spaceships out of the planet's gravity well without the limitations of rockets and having to carry rocket fuel.
* UniversalTranslator: "First Contact"
* WireDilemma: In ''Second Landing'' the main character has to disable an atomic bomb ''built by aliens''. Eventually [[spoiler:he realizes that in all atomic bombs, no matter who built them, the explosives surrounding the fissionable core have to fire in a perfectly synchronized sequence or the bomb will fizzle. So he shoots the bomb with a bazooka, prematurely detonating some of the explosives.]]
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