While the fictional book in Jorge Luis Borges’ The Garden of Forking Paths resembles, and may have inspired, the many-worlds hypothesis in quantum mechanics, Borges was not the first to describe such an idea.
In Borges` short story, the fictional Sinologist Stephen Albert describes Ts`ui Pen’s “The Garden of Forking Paths” as essentially a “Choose Your Own Adventure” novel; the story branches based on choices the characters make. However, there are three things which set it apart from the modern version: Firstly, the reader can see everything happening in all the stories at once- if there were two stories being told, the book would list a part of the first story, then the same part, chronologically, of the second story, then the next part of the two stories, and so forth. (This style of writing is sometimes referred to as “hypertext fiction”) Another thing which is unconventional is that sometimes two stories merge. As Albert said to Dr. Tsun, in one path the protagonist came to his house as a friend; in another, as an enemy. In the book, an army marched through the mountains, and after acquiring a disdain for life, won the battle easily; alternatively, the same army passed through a palace in which a ball was being held, and because of this, won the battle the same way. Lastly, some things are inevitable: In life, this is death; in the story, this is the fact that Captain Richard Madden will capture the narrator.
To digress for now to the second topic: In the field of quantum mechanics, the Many-Worlds hypothesis (first printed by Hugh Everett in 1957, 16 years after Borges` story) is in its simplest state the idea that every time someone or something makes a choice, the universe branches off into many other universes, in each of which a different one of the possible choices was made. The usual example of this is the Schrödinger’s Cat thought experiment. Imagine a cat was placed in a box, and a device inside the box then flips a coin and measures whether it falls on heads or tails. If it falls on tails, it kills the cat; otherwise, it does nothing. After the first coin flip, the universe can be thought of as splitting into two different universes: one in which the cat is dead, and another in which the cat is alive. By observing the state of the cat, the experimenter can see which universe he’s in, but he can’t suddenly switch from the “plot” of one universe to the plot of another.
Ts`ui Pen’s story shares many things with this theory: they both involve branching due to choices, the idea of separate timelines, and in fact Stephen Albert claimed “The Garden of Forking Paths” was, like Many-Worlds, “an incomplete, but not false, image of the universe”. The two ideas differ only in that Pen’s includes universes merging and inevitable events, while in the Many-Worlds hypothesis universes can’t merge, and there are somewhat extreme ways to keep otherwise inevitable events from happening. (See , pp. 26-27, 32-33, 54-57)
As it turns out, while the style of writing in Ts`ui Pen’s fictional book certainly was original, the most important ideas appeared more than half a century before Borges` story, in Lewis Carroll’s little-known novel Sylvie and Bruno, published in 1889. In the beginning of Chapter 23, the narrator witnesses a tragic event: a box is left in the street and a bicyclist crashes into the box and is flung over the handlebars, causing him to get very badly injured and go to the hospital. Using a magical watch, the narrator goes back to before the crash, removes the box, which causes the bicyclist not to crash. However, at precisely the time he wound the watch backwards, the scene instantaneously switches to the bicyclist in the hospital, with exactly the same injuries as when the narrator didn’t remove the box.
While this might initially seem strange, it can be interpreted as follows: At time, say, 1:00, the universe bifurcates into two different universes: A, in which the narrator does not remove the box; and B, in which he does. Initially, we see the narrator go down the timeline of universe A, but then at 1:30 (when the bicyclist is in the hospital of universe A) he goes back in time just before the bifurcation point. Here, he chooses to go down the path of universe B, and for a while he remains in that timeline, until 1:30, at which the narrator from universe A is returned to universe A. (It is unclear what the state of narrator B is during this timespan- are there two copies of the narrator, or is narrator A seeing the world through narrator B’s eyes?) In this way, Carroll not only gave the idea for the Many-Worlds hypothesis, but also presented how time travel might work in such a system. Carroll’s model shares the aspects of branching based on choices with Borges’ story and the Many-Worlds hypothesis, and shares merging and inevitability with Borges’ model.
As with anything, there are a few objections that could be made- Carroll’s model switches back abruptly, as if a scene from a film had been replaced with another scene that just happened to match at the beginning, which seems unnatural; Ts`ui Pen’s novel shows every universe happening at once, which certainly the inhabitants of our universe don’t see; the description of universes ‘bifurcating’ is just a way to think of the evolution of the wave function, and so forth. However, one can definitely conclude from the evidence given that Borges’ Garden of Forking Paths, Carroll’s Magic Watch tale, and the Many-Worlds hypothesis resemble each other- and perhaps one even inspired another.
 Joseph Luis Borges, “The Garden of Forking Paths” – from Collected Fictions, translated by Andrew Hurley. Published by the Penguin Group, 1998.
 Lewis Carroll, “Sylvie and Bruno”. From The Collected Works of Lewis Carroll, 2005 Barnes and Noble edition. Illustrated by John Tenniel.
 Jason Shiga, “Meanwhile”, Second Edition. Published by Amulet Books, 2010.