Long-debated notions of parallel universes came to the fore in the 19th century with William James’s philosophical works and the social satire Flatland, but it wasn’t until midway through the 20th century that physicist Hugh Everett III codified the idea with his “many-worlds interpretation.” In 1997 physicist David Deutsch refined the theory in The Fabric of Reality, and the science-fiction worlds of Neal Stephenson’s Anathem and TV’s Fringe further explore the possibilities of the multiverse.
William James, brother to novelist Henry, was a multidisciplinary scholar, a founder of modern psychology and the author of the 1895 essay “Is Life Worth Living?” in which he coined the term multiverse. James touched on many subjects throughout his career, and his later reflections on religion and reality contributed to his ever-evolving opinions on philosophies such as pluralism. In 1909’s A Pluralistic Universe, James argues that reality is full of unrealized “connexions” that may or may not be realized in the future, depending on the actions of individuals.
James’s breakdown of reality is akin to Hugh Everett III’s many-worlds interpretation of quantum physics. The work of James and Everett could not be more different, yet Everett would not have tossed James’s lecture notes out the window (as many philosophers did). He explicitly states that what we experience is but one of many possible realities, based on which of our actions and observations manifest themselves. Everett describes how these worlds coexist in terms of physical laws and a principle he calls the universal wavefunction. This “basic physical entity” of existence, he argues, generates a near-infinite number of parallel universes—possibly the result of realized “connexions.”
In 1957 Hugh Everett III became the first quantum physicist to conceive of multiple universes (the many-worlds interpretation, or MWI). At the time, physicists were unable to explain the paradoxes of subatomic behavior. Everett postulated that reality is constantly splitting into alternate worlds based on probabilities and what he called “universal wavefunction”—the quantum state of all existence. What occurs at the subatomic level, he speculated, holds true across the universe.
It took the scientific community a long time to catch up with Everett, but it finally did. After seeing his work ignored for 20 years, Everett was invited to present his theories at a 1977 conference at the University of Texas at Austin. In the audience was a young David Deutsch, who eagerly questioned Everett about MWI. Deutsch took Everett’s ideas and tossed them in a blender with Karl Popper’s epistemology, Alan Turing’s computation and Richard Dawkins’s take on Darwinian evolution. The result (another 20 years later): The Fabric of Reality, Deutsch’s stab at the elusive “theory of everything,” a complete, unified theory that explains all natural physical laws, both Newtonian (macro) and quantum (micro). In the words of alternate-reality-fiction guru Kurt Vonnegut, “Listen, it’s complicated.”
Square, the protagonist of Flatland: A Romance of Many Dimensions, lives in a 2-D world. When he’s visited by Sphere, who introduces him to a third dimension, his mind is consequently blown. But no one in Flatland believes Square about any world beyond their own. Though Flatland is a satirical picture of 19th-century England, with the characters’ shapes determining their social caste, the novel found a wide audience in the 20th century because of Square’s dreams of fourth and fifth dimensions and beyond.
Square’s unfriendly treatment by the closed-minded of Flatland could have served as a cautionary tale to physicist Hugh Everett III, who published a paper about the existence of multiple universes. Even his mentor at Princeton in the mid-1950s, John A. Wheeler of Manhattan Project notoriety, believed Everett’s ideas were so radical that most physicists would reject them. That’s precisely what happened. When Wheeler brought Everett to Copenhagen in 1959 to meet his own mentor, Niels Bohr—a legend in physics—Bohr refused to discuss Everett’s theories.
The tides eventually turned, and Everett’s views came into acceptance two decades after he proposed them. Today’s string theory, whose proponents include theoretical physicist Stephen Hawking, presupposes a whopping 11 dimensions.
Neal Stephenson has said the Polycosm theory from his novel Anathem is an analog for David Deutsch’s notion of the multiverse. Deutsch asserts in his breakthrough book, The Fabric of Reality, that each of us has identical copies inhabiting parallel universes. In Stephenson’s novel these universes are inescapably linear, thus known as “Narratives” by the Avouts, a class of monk-scholars who toss around all kinds of physicist slang (as monk-scholars are wont to do). They discover long-hidden knowledge about the nature of consciousness across the multiverse, which enables them to see into alternate worlds.
According to the many-worlds interpretation of quantum physics, on which Deutsch bases his book (on which Stephenson bases his), communication between universes should be impossible, due to their very linearity. Universes interact only indirectly, through subatomic interference phenomena—think particles, not people. Particle interaction is also the basis for quantum theory and, therefore, the multiverse. People, however, are bound by Isaac Newton’s pesky physical laws.
Then again, Deutsch never explicitly rules out telepathy between oneself and a copy of oneself, so Anathem cleverly walks the line between what is possible (according to Deutsch) and what has not yet been proved impossible.
The notion of the multiverse comes brilliantly into play late in Neal Stephenson’s Anathem, when Erasmas, the protagonist, experiences multiple “Narratives” branching out across the same span of time. Each Narrative carries a different set of events—a story line of one universe’s probabilities made real—with only one progressing toward the novel’s conclusion. As Erasmas’s mentor, Orolo, explains early in the novel, our conscious minds—along with everything else—exist in all universes simultaneously. By properly harnessing the quantum activity in his brain, Erasmas connects with copies of himself in alternate universes via their shared consciousness.
Olivia Dunham, an FBI agent investigating fringe science cases in Fox’s sequential drama Fringe, has nearly the same experience. In the episode “The Road Not Taken,” she begins having random flashbacks, which can be jarring enough. But these visions are not quite how she recollects the events: An office is arranged differently, for example, or two bodies are found at a crime scene instead of one. Eventually she and her team realize that their universe is one of at least two created by probabilities and that she, like Erasmas, is one of the few people who can be “tuned” to other worlds.
In the first-season finale of Fox’s sci-fi drama Fringe, viewers finally get a glimpse of a mysterious parallel universe: Zeppelins drift across the sky, New York’s World Trade Center towers stand, JFK is still alive and, perhaps even more unimaginable, Michael J. Fox never replaced Eric Stoltz as the lead in Back to the Future. This is a universe similar to our own, yet obviously with an alternate history. Perhaps most astonishing of all, the U.S. has been a cell phone culture since the 1980s! Where would that place its technology in the 21st century? Way beyond that of our own universe, it turns out, an element crucial to the show’s story line.
In The Fabric of Reality, David Deutsch discusses the inevitability of exactly such a scenario. After a full-throated defense of the many-worlds interpretation of quantum physics, Deutsch explains how various universes exist within the multiverse. Any if-then statements we can make (that are allowed by physical laws) are objective facts, not subjective fantasies. So, Deutsch would argue, every detail Fringe’s writers dream up is a reality somewhere in the multiverse. If you imagine it, then it exists—and it exists even if you don’t.