Parallel universes are no longer only a plot device in a good science fiction novel. Some scientific ideas now indicate the existence of parallel universes to our own. The multiverse theory, on the other hand, remains one of science’s most divisive concepts.
The size of our cosmos is unfathomable. Hundreds of billions, if not trillions, of galaxies, each containing billions or trillions of stars, are rotating through space. According to some experts examining cosmos models, the universe’s diameter could be 7 billion light-years across. Others believe it might go on indefinitely.
Is it, however, all there is? The idea of a parallel world and the possibility that we are living one of an unlimited number of lifetimes is a popular one in science fiction. However, multiverses aren’t just for “Star Trek,” “Spiderman,” and “Doctor Who.” The case for universes beyond, parallel to, or remote from but mirroring our own is explored, and in some cases supported, by serious scientific theory parallel universes and multiverses are frequently discussed in conjunction with other key scientific concepts such as the Big Bang, string theory, and quantum mechanics.
THE BIG BANG THEORY, ETERNAL INFLATION, AND PARALLEL UNIVERSES
Everything we know was an infinitesimal singularity around 13.7 billion years ago. Then it exploded, expanding faster than the speed of light in all directions for a fraction of a second, according to the Big Bang theory.
In a process known as cosmic inflation, the cosmos blasted outward to 1026 times its original size in less than 10-32 seconds.
And that’s before the real expansion of matter known as the Big Bang, which was a result of all of this inflation: As inflation slowed, a torrent of matter and radiation erupted, forming the classic Big Bang fireball and the atoms, molecules, stars, and galaxies that now inhabit the vastness of space around us some scholars believe that several universes are possible, if not highly likely, due to the enigmatic process of inflation and the Big Bang.
According to Tufts University theoretical physicist Alexander Vilenkin, inflation did not halt everywhere at the same time.
While cosmic inflation ended 13.8 billion years ago for everything we can see on Earth, it continues in other locations. This is known as the endless inflation theory. In 2011, Vilenkin wrote for Scientific American about how when inflation stops in one area, a new bubble universe emerges.
Because they continue to expand eternally, those bubble worlds are unable to communicate with one another. We’d never reach the edge of our bubble, where it might collide with the next bubble universe over, because the edge is speeding away from us faster than the speed of light, and faster than we could travel.
Even if we could reach the next bubble, perpetual inflation (coupled with string theory) suggests that our familiar universe, with its physical constants and habitable conditions, may differ from the hypothetical bubble universe next to ours.
PARALLEL UNIVERSES AND QUANTUM MECHANICS
Parallel universes are based on quantum physics, the mathematical description of subatomic particles, according to some academics.
Multiple states of existence for microscopic particles are all possible at the same time in quantum mechanics, and a “wave function” contains all of them.
When we look, though, we only see one of the possibilities. We see an outcome when the wave function “collapses” into a single reality, according to the Copenhagen interpretation of quantum mechanics, as defined by the Stanford Encyclopedia of Philosophy.
The many-worlds theory, on the other hand, suggests that for every observed condition or outcome, another “world” exists in which a different quantum outcome becomes reality. This is a branching arrangement in which our visible universe branches into near-infinite options, one after the other.
Those parallel worlds are wholly separate and unable to collide, so while there may be many versions of you living lives that are slight — or dramatically — different from yours in this world, you’d never know. According to physicist Sean Carroll, in his book “Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime,” the many-worlds hypothesis is the most “courageous” approach to the quantum mechanics conundrum (Dutton, 2019). He also claimed that it is the most straightforward theory, notwithstanding its flaws.
One of these flaws is that the many-world concept is untestable. This is a crucial aspect of scientific thinking, as it is how the scientific community creates ideas that can be tested through observation and experimentation. It’s bad for science as a whole if there’s no way to gather evidence to refute a theory.
INFINITE UNIVERSES, INFINITE SPACE?
A flatter version of multiple worlds is believed by some physicists. That is, if the cosmos we live in continues indefinitely, the building elements of matter can only organize themselves in so many different ways as they assemble across limitless space. Any limited number of particle kinds must eventually replicate a specific layout. In a large enough region, such particles should theoretically be able to repeat arrangements as huge as entire solar systems and galaxies.
As a result, your entire existence, right down to what you ate for breakfast yesterday, maybe replicated somewhere in the cosmos. That is, at least, the theory.
According to astronomer Ethan Siegel’s 2015 Medium essay, if the universe originated at a limited moment, as nearly every physicist agrees, an alternate version of you is unlikely to exist.
“The number of conceivable outcomes from particles in any Universe interacting with one another grows to infinity faster than the number of possible Universes increases owing to inflation,” according to Siegel.
“So, how does this affect you?” Siegel penned an essay. “It signifies that it’s up to you to make this Universe worthwhile.”
THE UNIVERSE OF MIRROR-IMAGE
Researchers from the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, have postulated that the universe began with the Big Bang — and that a universe existed on the opposite side of the Big Bang timeline, stretching backward in time, that was a perfect mirror image of our own.
“Instead of saying there was a different universe before the big bang, we’re saying the universe before the big bang is, in some ways, an image of the universe after the big bang,” Neil Turok, a Perimeter Institute researcher, told Live Science, a sister site of Space.com.
Everything would be reversed, including protons, electrons, and even acts like cracking an egg. Atoms would be made out of antiprotons and positively charged electrons, while eggs would uncrack and return to chickens. That universe would eventually contract, presumably to a singularity, before extending out into ours.
To put it another way, both worlds were born at the Big Bang and blasted backward and forward in time at the same moment.
ARGUMENTS FOR AND AGAINST MULTIVERSITY
Arguments in favor of the notion of the multiverse
Inflation in the universe
In the early moments of its existence, our cosmos expanded tremendously, but was this expansion uniform? If not, it means that distinct portions of space grew at different speeds, possibly isolating them.
Constants in mathematics
What makes the universe’s laws so precise? Some argue that this happened entirely by coincidence — that we are one universe among many that just happened to have the correct numbers.
The universe that can be seen
What lies beyond the observable space that surrounds us? No one knows for sure, and until we do (which may never happen), the idea that our universe will continue to expand endlessly is intriguing.
Objections to the Multiverse Theory
We will never be able to put multiverse theories to the test. We will never be able to see beyond the observable cosmos, thus should hypotheses be given credit if there is no means to debunk them?
The principle of Occam’s Razor
Sometimes the most basic concepts are the most effective. Some scientists argue that the multiverse theory is unnecessary. It doesn’t resolve any paradoxes and only adds to the confusion.
There is no proof.
We can’t prove or disprove any multiverse idea, and we can’t even deny them. There is no proof that multiverses exist at this time, and everything we can observe suggests that there is only one universe – our own.
IN FICTION, PARALLEL UNIVERSES
Parallel universes and the multiverse have been referenced in numerous works of myth and fiction. In Norse mythology, as well as Buddhist and Hindu cosmology, overlapping worlds emerge. The concept of several universes colliding first appeared in literature in Edwin A. Abbott’s novella “Flatland: A Romance of Many Dimensions” (Seeley & Co., 1884), and it can still be seen in current films like Marvel’s “Doctor Strange” from 2016. According to the New York Public Library, an entire genre of Japanese graphic novels known as isekai deals with protagonists transferred to parallel universes.
Almost every “Star Trek” series features a mirror world, and the 2009 reboot film starring Chris Pine and Zachary Quinto shifted following “Star Trek” films into an entirely new timeline that diverges from the original series.
And comic books, as well as their film adaptations, explore the concept of parallel worlds in great depth. Multiple universes and their crossings are explored in recent Marvel Comics storylines (both film and print), DC’s Flashpoint narrative, and 2018’s “Into the Spider-Verse.”
The following is a partial list of fictional appearances of multiverses, split-timeline worlds, and parallel universes:
- Spider-man: No Way Home
- Into the Spider-Verse (2018)
- Terminator Genisys (2015)
- Phineas and Ferb the Movie: Across the Second Dimension (2011)
- Star Trek (2009)
- Donnie Darko (2001)
- Run Lola Run (1998)
- Sliding Doors (1998)
- Back to the Future 1-3 (1985, 1989, 1990)
- The Adventures of Buckaroo Banzai Across the 8th Dimension (1984)
- Star Trek: Discovery, multiple episodes, Enterprise, multiple episodes, Deep Space Nine, multiple episodes, The Next Generation, “Parallels” (Episode 11, Season 7) (1993), and The Original Series, “Mirror, Mirror”, (Episode 4, Season 2) (1967)
- Doctor Who, multiple episodes
- Sliders, entire series
- Community, “Remedial Chaos Theory” (Episode 4, Season 3) (2011)
- Rick and Morty, multiple episodes
- Futurama, multiple episodes
- Eureka, multiple episodes
- Agents of Shield, multiple episodes
- “The Chronicles of Narnia” series (Geoffrey Bles, 1950-56) by C. S. Lewis
- “His Dark Materials” series (Scholastic, 1995-2000) by Phillip Pullman
- The “Discworld” series (HarperCollins, 1983-2015) by Terry Pratchett
- “Men Like Gods” (Macmillan, 1923) by H. G. Wells
- “The Dark Tower” series (Donald M. Grant, 1982-2012) by Stephen King
- BioShock Infinite, 2013
- Kingdom Hearts, 2002-2020
- Chrono Cross, 1999
- Half-Life, 1998-2020
- Metroid Prime 2: Echoes, 2004
- Zero Escape, 2009-2016