Editing Alternate history (section)

===Early 20th century and the era of the pulps===
In 1905, [[H. G. Wells]] published ''[[A Modern Utopia]]''. As explicitly noted in the book itself, Wells's main aim in writing it was to set out his social and political ideas, the plot serving mainly as a vehicle to expound them. This book introduced the idea of a person being transported from a point in our familiar world to the precise geographical equivalent point in an alternate world in which history had gone differently. The protagonists undergo various adventures in the alternate world, and then are finally transported back to our world, again to the precise geographical equivalent point. Since then, that has become a staple of the alternate history genre.

A number of alternate history stories and novels appeared in the late 19th and early 20th centuries (see, for example, [[Joseph Edgar Chamberlin]]'s ''[[s:The Ifs of History|The Ifs of History]]'' [1907] and [[Charles Petrie (historian)|Charles Petrie]]'s ''If: A Jacobite Fantasy'' [1926]).<ref>{{Cite book |last=Petrie |first=Charles |url=https://books.google.com/books?id=IMhXyZxSRd8C |title=The Stuart Pretenders: A History of the Jacobite Movement, [1688-1807] |date=1934 |publisher=Houghton Mifflin |pages=Appendix VI |language=en}}</ref> In 1931, British historian [[Sir John Squire]] collected a series of essays from some of the leading historians of the period for his anthology ''[[If It Had Happened Otherwise]]''. In that work, scholars from major universities, as well as important non-academic authors, turned their attention to such questions as "If the Moors in Spain Had Won" and "If [[Louis XVI]] Had Had an Atom of Firmness". The essays range from serious scholarly efforts to [[Hendrik Willem van Loon]]'s fanciful and satiric portrayal of an independent 20th-century [[New Amsterdam]], a Dutch [[city-state]] on the island of [[Manhattan]]. Among the authors included were [[Hilaire Belloc]], [[André Maurois]], and [[Winston Churchill]].

One of the entries in Squire's volume was Churchill's "If Lee Had Not Won the Battle of Gettysburg", written from the viewpoint of a historian in a world in which the [[Confederate States of America|Confederacy]] had won the [[American Civil War]]. The entry considers what would have happened if the North had been victorious (in other words, a character from an alternate world imagines a world more like the real one we live in, although it is not identical in every detail). Speculative work that narrates from the point of view of an alternate history is variously known as "[[recursive alternate history]]", a "double-blind what-if", or an "alternate-alternate history".<ref>{{cite web |url=http://www.winstonchurchill.org/i4a/pages/index.cfm?pageid=674 |title=If Lee Had Not Won the Battle of Gettysburg - The Churchill Centre |date=6 December 2006 |access-date=26 January 2016 |url-status=dead |archive-url=https://web.archive.org/web/20061206031128/http://www.winstonchurchill.org/i4a/pages/index.cfm?pageid=674 |archive-date=6 December 2006 }}</ref> Churchill's essay was one of the influences behind [[Ward Moore]]'s alternate history novel ''[[Bring the Jubilee]]''{{citation needed|date=January 2013}} in which General [[Robert E. Lee]] won the [[Battle of Gettysburg]] and paved the way for the eventual victory of the Confederacy in the American Civil War (named the "War of Southron<!--Southron, with two ''o''s is the word used in the novel, not a misspelling.--> Independence" in this timeline). The protagonist, the autodidact Hodgins Backmaker, travels back to the aforementioned battle and inadvertently changes history, which results in the emergence of our own timeline and the consequent victory of the [[Union (American Civil War)|Union]] instead.

The American humorist author [[James Thurber]] parodied alternate history stories about the American Civil War in his 1930 story "If Grant Had Been Drinking at Appomattox", which he accompanied with this very brief introduction: "''Scribner's'' magazine is publishing a series of three articles: 'If Booth Had Missed Lincoln', 'If Lee Had Won the Battle of Gettysburg', and 'If Napoleon Had Escaped to America'. This is the fourth".

Another example of alternate history from this period (and arguably<ref>{{cite web|title=Vaughan, Herbert M|website=SFE: The Encyclopedia of Science Fiction|url=http://www.sf-encyclopedia.com/entry/vaughan_herbert_m}} [[Herbert Millingchamp Vaughan]]'s ''The Dial of Ahaz'' (1917) posits a multiverse filled with alternate versions of planet Earth.</ref> the first that explicitly posited [[Time travel in fiction|cross-time travel]] from one universe to another as anything more than a visionary experience) is [[H.G. Wells]]' ''[[Men Like Gods]]'' (1923) in which the [[London]]-based [[journalist]] Mr. Barnstable, along with two cars and their passengers, is mysteriously teleported into "another world", which the "Earthlings" call Utopia. Being far more advanced than Earth, Utopia is some 3000 years ahead of humanity in its development. Wells describes a [[multiverse]] of alternative worlds, complete with the paratime travel machines that would later become popular with American pulp writers. However, since his hero experiences only a single alternate world, the story is not very different from conventional alternate history.<ref>{{cite book|url=http://gutenberg.net.au/ebooks02/0200221.txt |title=Men Like Gods |publisher=Gutenberg.net.au |access-date=|date = 1923|first = H.G.|last = Wells}}</ref>

In the 1930s, alternate history moved into a new arena. The December 1933 issue of ''[[Analog Science Fiction and Fact|Astounding]]'' published [[Nat Schachner]]'s "Ancestral Voices", which was quickly followed by [[Murray Leinster]]'s "[[Sidewise in Time]]" (1934). While earlier alternate histories examined reasonably-straightforward divergences, Leinster attempted something completely different. In his "World gone mad", pieces of Earth traded places with their analogs from different timelines. The story follows Professor Minott and his students from a fictitious Robinson College as they wander through analogues of worlds that followed a different history.{{Citation needed|reason=Unsourced |date=February 2024}} "Sidewise in Time" has been described as "the point at which the alternate history narrative first enters science fiction as a plot device" and is the story for which the [[Sidewise Award for Alternate History]] is named.<ref>{{cite book |last1=Morgan |first1=Glyn |last2=Palmer-Patel |first2=Charul  |date= 2019-10-31 |title=Sideways in Time: Critical Essays on Alternate History Fiction |url=https://www.cambridge.org/core/books/abs/sideways-in-time/introduction/9C1C3D0467694F48AAC94A164173111C |location=Cambridge, England |publisher=Liverpool University Press |pages=11–28 |isbn=978-1789620139}}</ref><ref name="Chris 2022 e410">{{cite web | title=Civilizations by Laurent Binet Wins the 2021 Sidewise Award | website=Eisenhower Public Library | date=September 21, 2022 | url=https://eisenhowerlibrary.org/civilizations-by-laurent-binet-wins-the-2021-sidewise-award/ | access-date=February 19, 2024 | last1=Marketing | first1=Chris }}{{Dead link|date=May 2025 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

[[File:Fatherland.png|thumb |right | 300px|The world in 1964 in the novel ''[[Fatherland (novel)|Fatherland]]'' in which the Nazis won [[World War II]]]]
A somewhat similar approach was taken by [[Robert A. Heinlein]] in his 1941 novelette ''[[Elsewhen]]'' in which a professor trains his mind to move his body across timelines. He then hypnotizes his students so that they can explore more of them. Eventually, each settles into the reality that is most suitable for him or her. Some of the worlds they visit are mundane, some are very odd, and others follow science fiction or fantasy conventions.

[[World War II]] produced alternate history for [[propaganda]]: both British and American<ref>{{cite book|last1=Rosenfeld|first1=Gavriel D.|title=The World Hitler Never Made: Alternate History and the Memory of Nazism|date=2005|publisher=Cambridge Univ. Press|location=Cambridge|isbn=0-521-84706-0|pages=39, 97–99|edition=1. publ.}}</ref> authors wrote works depicting Nazi invasions of their respective countries as cautionary tales.

====Time travel to create historical divergences====
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The period around World War II also saw the publication of the [[time travel]] novel ''[[Lest Darkness Fall]]'' by [[L. Sprague de Camp]] in which an American academic travels to [[Italy]] at the time of the Byzantine invasion of the [[Ostrogoths]]. De Camp's time traveler, Martin Padway, is depicted as making permanent historical changes and implicitly forming a new time branch, thereby making the work an alternate history.

In [[William Tenn]]'s short story ''Brooklyn Project'' (1948), a tyrannical US Government brushes aside the warnings of scientists about the dangers of time travel and goes on with a planned experiment - with the result that minor changes to the prehistoric past cause Humanity to never have existed, its place taken by tentacled underwater intelligent creatures - who also have a tyrannical government which also insists on experimenting with time-travel.<ref>{{cite web |last1=Jonas |first1=Gerald |title=William Tenn, Science Fiction Author, Is Dead at 89 |url=https://www.nytimes.com/2010/02/14/books/14tenn.html |archive-url=https://ghostarchive.org/archive/20220101/https://www.nytimes.com/2010/02/14/books/14tenn.html |archive-date=1 January 2022 |url-access=limited |website=[[The New York Times]] |accessdate=5 April 2020 |date=13 February 2010}}{{cbignore}}</ref>

In [[Ray Bradbury]]'s classic short story "[[A Sound of Thunder]]" (1952) a group of hunters travel to the [[Late Cretaceous]] to hunt dinosaurs whose death would not be considered consequential as they are about to die a natural death within two minutes of the encounter. To minimize risking  changes history they are told to stay on a levitating antigravity path that touches nothing. However one of the hunters stumbles off the path, inadvertently crushing a butterfly. When the group returns they find that history became significantly harsher and a fascist is now President.<ref>{{cite book |editor-last=Vandermeer |editor-first=Ann and Jeff |date=Mar 18, 2014 |title=The Time Travelers Almanac  |location= |publisher=TORDOTCOM |page= |isbn=978-0765374240 }}</ref>

Time travel as the cause of a [[point of divergence]] (POD), which can denote either the bifurcation of a historical timeline or a simple replacement of the future that existed before the time-travelling event, has continued to be a popular theme. In [[Ward Moore]]'s ''[[Bring the Jubilee]]'' (1953), the protagonist lives in an alternate history in which the Confederacy has won the American Civil War. He travels backward through time and brings about a Union victory at the Battle of Gettysburg.

When a story's assumptions about the nature of time travel lead to the complete replacement of the visited time's future, rather than just the creation of an additional time line, the device of a "time patrol" is often used where guardians move through time to preserve the "correct" history.

A more recent example is ''[[Making History (novel)|Making History]]'' by [[Stephen Fry]] in which a time machine is used to alter history so that [[Adolf Hitler]] was never born. That ironically results in a more competent leader of [[Nazi Germany]] and results in the country's ascendancy and longevity in the altered timeline.

====Quantum theory of many worlds====
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While many justifications for alternate histories involve a [[multiverse]], the [[Many-worlds interpretation|"many world" theory]] would naturally involve many worlds, in fact a continually exploding array of universes. In quantum theory, new worlds would proliferate with every quantum event, and even if the writer uses human decisions, every decision that could be made differently would result in a different timeline. A writer's fictional multiverse may, in fact, preclude some decisions as humanly impossible, as when, in ''[[Night Watch (Discworld)|Night Watch]]'', [[Terry Pratchett]] depicts a character informing Vimes that while anything that can happen, has happened, nevertheless there is no history whatsoever in which Vimes has ever murdered his wife. When the writer explicitly maintains that ''all'' possible decisions are made in all possible ways, one possible conclusion is that the characters were neither brave, nor clever, nor skilled, but simply lucky enough to happen on the universe in which they did not choose the cowardly route, take the stupid action, fumble the crucial activity, etc.; few writers focus on this idea, although it has been explored in stories such as [[Larry Niven]]'s story ''[[All the Myriad Ways#story|All the Myriad Ways]]'', where the reality of all possible universes leads to an epidemic of suicide and crime because people conclude their choices have no moral import.

In any case, even if it is true that every possible outcome occurs in some world, it can still be argued that traits such as bravery and intelligence might still affect the relative frequency of worlds in which better or worse outcomes occurred (even if the total number of worlds with each type of outcome is infinite, it is still possible to assign a different [[Measure (mathematics)|measure]] to different infinite sets). The physicist [[David Deutsch]], a strong advocate of the many-worlds interpretation of quantum mechanics, has argued along these lines, saying that "By making good choices, doing the right thing, we thicken the stack of universes in which versions of us live reasonable lives. When you succeed, all the copies of you who made the same decision succeed too. What you do for the better increases the portion of the multiverse where good things happen."<ref>{{cite web|url=http://www.kurzweilai.net/taming-the-multiverse |title=Taming the Multiverse |publisher=KurzweilAI |access-date=|first = Marcus|last = Chown|date = 7 August 2001}}</ref> This view is perhaps somewhat too abstract to be explored directly in science fiction stories, but a few writers have tried, such as [[Greg Egan]] in his short story ''The Infinite Assassin'', where an agent is trying to contain reality-scrambling "whirlpools" that form around users of a certain drug, and the agent is constantly trying to maximize the consistency of behavior among his alternate selves, attempting to compensate for events and thoughts he experiences, he guesses are of low measure relative to those experienced by most of his other selves.

Many writers—perhaps the majority—avoid the discussion entirely. In one novel of this type, H. Beam Piper's ''[[Lord Kalvan of Otherwhen]]'', a Pennsylvania State Police officer, who knows how to make gunpowder, is transported from our world to an alternate universe where the recipe for gunpowder is a tightly held secret and saves a country that is about to be conquered by its neighbors. The paratime patrol members are warned against going into the timelines immediately surrounding it, where the country ''will'' be overrun, but the book never depicts the slaughter of the innocent thus entailed, remaining solely in the timeline where the country is saved.

The cross-time theme was further developed in the 1960s by [[Keith Laumer]] in the first three volumes of his ''Imperium'' sequence, which would be completed in ''Zone Yellow'' (1990). Piper's politically more sophisticated variant was adopted and adapted by [[Michael Kurland]] and [[Jack Chalker]] in the 1980s; Chalker's ''[[G.O.D. Inc]]'' trilogy (1987–89), featuring paratime detectives Sam and Brandy Horowitz, marks the first attempt at merging the paratime thriller with the police procedural.{{Citation needed|date=July 2008}} Kurland's ''[[Perchance (novel)|Perchance]]'' (1988), the first volume of the never-completed "Chronicles of Elsewhen", presents a multiverse of secretive cross-time societies that utilize a variety of means for cross-time travel, ranging from high-tech capsules to mutant powers. [[Crosstime Traffic]] is a 6-book series written by [[Harry Turtledove]] aimed at teenagers featuring a variant of H. Beam Piper's paratime trading empire. While the home timeline appears to be the same in each of the books there is no overlap in characters or repetition of the alternative worlds.

====Rival paratime worlds====
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The concept of a cross-time version of a world war, involving rival paratime empires, was developed in [[Fritz Leiber]]'s Change War series, starting with the [[Hugo Award]] winning ''[[The Big Time (novel)|The Big Time]]'' (1958); followed by [[Richard C. Meredith]]'s ''Timeliner'' trilogy in the 1970s, [[Michael McCollum]]'s ''A Greater Infinity'' (1982) and [[John Barnes (author)|John Barnes']] ''Timeline Wars'' trilogy in the 1990s.

Such "paratime" stories may include speculation that the laws of nature can vary from one universe to the next, providing a science fictional explanation—or veneer—for what is normally fantasy. [[Aaron Allston]]'s ''Doc Sidhe'' and ''Sidhe Devil'' take place between our world, the "grim world" and an alternate "fair world" where the Sidhe retreated to. Although technology is clearly present in both worlds, and the "fair world" parallels our history, about fifty years out of step, there is functional magic in the fair world. Even with such explanation, the more explicitly the alternate world resembles a normal fantasy world, the more likely the story is to be labelled fantasy, as in Poul Anderson's "House Rule" and "Loser's Night". In both science fiction and fantasy, whether a given parallel universe is an alternate history may not be clear. The writer might allude to a POD only to explain the existence and make no use of the concept, or may present the universe without explanation of its existence.