Jonbar Hinge

A Jonbar Hinge is a science fiction conceit derived from a book by Jack Williamson, entitled "The Legion of Time". It refers to any crucial choice or event in a story about time travel where the outcome of the choice or event will lead to a different future.

It derives from a choice made by a boy in the story called John Barr, when picking up one of two objects (a magnet, and a pebble): choosing one will lead to a utopian civilisation named Jonbar, while the other to the tyranny of the state of Gyronchi.

Jonbar Hinges are essential concepts of Alternate World stories, where the consequences of a small action are evaluated in novel form; i. e., what would have happened if a certain decisive event had (or had not) happened? Alternate Worlds regularly are the setting for complex stories. Many authors assume infinite alternate worlds existing alongside each other, formed upon different "Jonbar instances", but unable to interact. In more narrowly allohistorical fiction (i.e. where the consequences to history in only one timeline are examined, and the emphasis is on the historical background), and in academic counterfactuals, the term is rarely used.

Depending on the Jonbar Hinge, any number of worlds may be devised by resourceful authors. Some tried-and-tested scenarios: intelligent life does not appear, the dinosaurs do not go extinct, Jesus is not crucified, Napoleon wins at Waterloo, Newton is killed by a falling apple, the South wins the American Civil War, Charles Babbage's computer works, or Hitler wins World War II.