Point of Divergence

A point of divergence is a specific event in an Alternate History Back Story that occurs differently than it did in Real Life. Most alternate history authors will change a single event, creating a "ripple effect", however, the point of divergence may range in importance and realism from a missing horseshoe nail to Time Travel and Alien Invasion.

Examples:

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    Comic Books 
  • In The New Universe it was supposed to be exactly like reality until the White Event. The slogan was "the world outside your window."

    Film 
  • In the Super Mario Bros. movie, the prologue explains that the alternate reality of the Mushroom Kingdom was identical to ours until the Chicxulub meteorite impact: in our timeline, the dinosaurs were killed off; in the Mushroom Kingdom, they weren't.

    Literature 
  • In Harry Turtledove's Worldwar series, World War II is interrupted by a fleet of lizard-people from outer space (a.k.a. The Race) in 1942. This is both unlucky and lucky for the aliens: if they'd shown up 50 years early they would've swiftly annihilated a planet who had yet to discover military flight, rocketry, and the basic building blocks of nuclear weapons. If The Race had shown up 50 years later they would have been soundly defeated by humans with modern technology that matched The Race but with much greater understanding of tactics and strategy, not to mention several nations having massive nuclear weapons programs.
  • The Years of Rice and Salt: The Black Death extinguished the European civilization.
  • Seekers of the Sky: Jesus was killed by Herod's troops and the Redeemer took his place as the Messiah.
  • In Randall Garrett's Lord Darcy series, history was changed when Richard I of England was not killed by the crossbow wound he took during the siege of Chalus-Chabrol. He returned to England and John never became king. Richard died in 1219 and his son Arthur took the throne.
  • L. Neil Smith's North American Confederacy series has the divergence as the result of a single word added to the Declaration of Independence, "governments derive their just power from the unanimous consent of the governed." Somehow, as a result, the Whiskey Rebellion was successful and the entire continent became a Libertarian utopia.
  • Harry Harrison uses the Trent Affair as the point of divergence for his Stars and Stripes trilogy, where Prince Albert dies before helping to resolve the incident peacefully, and the British Empire attempts to invade the US, resulting in both the USA and the CSA joining forces against the largest empire in history.
  • In William Shatner's Mirror Universe trilogy, it's revealed that the titular universe split off from the main one when Zephram Cochrane let a coin flip decide whether he would tell the Vulcans about the Borg or not. In the Prime 'verse, he hides the truth. In the Mirror Universe, he tells them, and they believe him, resulting in a much more militant union between the races in an attempt to prepare for the inevitable return of the Borg. Naturally, this is rendered non-canonic by Star Trek: Enterprise.
  • In Orson Scott Card's Pastwatch: The Redemption of Christopher Columbus, the focal point that brought our timeline into being is Christopher Columbus receiving a vision from God telling him to sail West to convert the Asian heathens to Christ. In the original timeline, he never received the vision, instead continuing his dream of retaking the Holy Land from the Muslims. He ends up leading the most devastating Crusade of all. Meanwhile, a progressive, bloodthirsty empire rises in Central America and, eventually, takes over the world. Their descendants invent Time Travel and sent a holographic message urging Columbus to go West. The goal of the protagonists is to create a third timeline that doesn't result in The End of the World as We Know It, throwing this trope out the window and going for a long-term approach.

    Live-Action TV 
  • Sliders, which deals with parallel universes on a regular basis, often has its main characters deduce the point of divergence between the universe they are currently in and their home universe (Earth Prime). In the pilot, the point of divergence between Earth Prime and the Communist-ruled USA world is the outcome of The Korean War (loss for the US as opposed to a draw).

    Roleplay 
  • For the major universes of We Are All Pokémon Trainers we have the following:
    • AU: Umbra getting sealed in an orb when he was the Ghost Lord, Hoenn getting flooded, Sinnoh suffering the Distortion, and Scolipede and Artemis taking over Unova.
    • PMD-B: The dragons succeeding in turning 99% of humanity into Pokémon.
    • Otherverse: The earliest known divergence is Grings Kodai using Azalea instead of Crown City for his Celebi plot.

    Video Games 
  • In the Fallout series, the PoD is World War II. The transistor was never invented, leading to desktop computers and robots that use vacuum tubes instead. This also had the world stuck in the social norms of the 1950's, for some reason.
  • In BioShock Infinite, the divergence point is the 1893 World Fair, or rather, the construction of the floating city of Columbia for said fair. More precisely, the divergence point is the baptism of Booker DeWitt, which created Father Comstock and ultimately made Columbia possible. In-game, Elizabeth has the power to use "tears" as divergence points to enter alternate timelines.
  • It's hard to establish where the point of divergence between Real Life and the Alternate Timelines of Shin Megami Tensei IV lies. Sometime before 2013, a suit of Powered Armor called the Demonica was invented, and Japan's Self Defense Force purchased a large amount of them. In 2013 itself, angels entered Earth from the Expanse, conspired to trigger a nuclear war, and started kidnapping innocents and God's Chosen to be spirited out of Earth when the nukes struck. In the chaos, a mysterious piece of software, the Demon Summoning Program, was dispersed through the Internet, giving some humans the chance to strike back. At the cusp of the angels' plan, with a large group of ICBMs looming over Tokyo, a young summoner made his stand, and through his choice created three possible worlds...