Before he died, renowned astrophysicist Stephen Hawking revealed a surprising fact: our universe is just one of many, which are finite and similar to one another. The parallel universe theory opens a door to the possible existence of alternate universes; we might be able to go there through black holes in space and time towards parallel universes where there would no longer be death, only multiple, independent lives.
What are parallel universes?
The contributions of quantum physics to relativity theory derived in a revolutionary vision of the universe's dimension that changed the very idea of reality, life and death for humans itself: the theory of the parallel universe.
According to this scientific theory, humans would have an existence with multiple chances for development and growth. That means we would not have just one life, but many, because even if we die in one universe we'll remain alive in other alternative dimensions. This is definitely a controversial theory that has been exploited by futuristic science fiction.
In fact, the first physicist who first proposed the parallel universe theory, Hugh Everett (1930-1982) gave up on his career, discouraged by the lack of support towards his theory from other physicists. The truth is, from a logical point of view, Everett's theory eludes many issues connected to more conventional interpretations of quantum mechanics.
The theory was developed in 1957 within the field of quantum physics, which sets the dimensional simultaneousness principle. This principle states that two or more physical objects, realities, perceptions and non-physical entities can co-exist in the same space-time. That brought on the multiple world theory, according to which the universe unravels into many alternative cosmic regions.
But then, why can't we find these other universes? According to scientists, the 5 senses humans have allow us to grasp reality in three dimensions only, and we would require many more to be able to watch and know other alternate dimensions. Thus, in order to do that, we should overcome our sensory limitations.
The parallel universe hypothesis and the theory of black holes
The Big Bang theory explains that the universe experienced a bright expansion. During a certain period of time, sections of space evolved at different speeds, thus creating different bubble universes. By picking up Hugh Everett's traces and basing himself on the theory of how the universe came to be, Stephen Hawking reached an amazing conclusion.
It was a few months prior to his death when the renowned astrophysicist, with his pupil Thomas Hertog, made public the results of a study which, according to his knowledge, has the main advantage of being able to be demonstrated through scientific observation.
The Hawking-Hertog hypothesis states that our universe is just one alternate reality of many, and that the parallel worlds currently in existence are not only finite, but similar worlds to one another as well. The idea comes from Hawking's 1983 studies, when he established that, after the Big Bang occurred, an endless amount of universes with a wide range of characteristics should have been created.
To these contributions, the discovery of black holes was added. Black holes are cold traces of dead stars which generate a concentric core whose gravity force no element in the universe can resist.
- Find out more about black holes: can you travel through space and time?
These great holes open in the midst of galaxies like great vacuums inspired the theory of space and time travelling. According to Stephen Hawking himself, these structures embody the second principle of thermodynamics, and they would act as portals through which we might be able to travel through space and time.
These observations brought the possibility of black holes being the door to parallel universes, which would basically entail the disappearance of the idea of death. A person would experience different lives at the same time in several independent dimensions.
Four fun facts on parallel universes
The idea of the existence of parallel universes which we can reach through black holes and live several lives at the same time in independent realities completely turns around our idea of reality. There are some fun facts as curious and surprising as the theory of parallel universes itself.
1. Aliens exist
The tempting idea of the existence of unknown parallel worlds was the motivation for the performance of computer simulations that offered revealing results: the existence of other dimensions with a larger proportion of dark matter would be compatible with the appearance of galaxies and places where life could come to occur.
Rumours stimulated the scientists' imagination that established through their studies that there could be alien civilisations in a hypothetical parallel universe trying to find reality, and perhaps other universes. Will we ever meet?
2. The theory of multiple existences
This is the most fascinating consequence of the parallel universe theory, because it brings up the idea that, when an important life choice comes around, we can always choose one alternative and the opposite thanks to parallel realities. In the same way, one could be an important emperor in one universe, and a homeless person in another.
There's also several stories online which, if real, would bring us an actual possibility for the existence of parallel universes.
One of those stories states that two girls riding a car turned into the wrong direction and found themselves in an unknown dimension with an altered reality and non-humans. Another story talks about the appearance at a Tokyo border control point of a man with a passport from Taured, a place that doesn't exist on Earth. When the police tried to catch him, he vanished.
3. Schrödinger's cat theory
Schrödinger cat's theory comes from a quantum physics experiment performed in 1935 by Austrian physicist Erwin Schrödinger. It is a test of intuition that proves the existence of parallel realities.
The experiment is about a cat trapped in a box with a poisonous gas bottle and a device with one radioactive particle with a 50% chance of disintegrating, which would release the poison and kill the cat. When the time runs out, the chances of the device activating and the cat being dead are 50%, and the chances of the device remaining dormant and the cat being alive are 50% as well.
When the scientist opens the box, the cat will be alive or dead. But according to quantum physics, electrons have the property of being able to be in two places at the same time, therefore able to be spotted by two receivers, so the cat is both alive and dead: it's an overlap. When the box is opened and the cat is found alive or dead, we will be altering the laws of quantum physics, thus disturbing the overlap status.
According to this experiment, the observer's intervention remains limited by the use of logic, which can't sort out the co-existence of multiple chances by itself.
4. Parallel universes influence one another
This is one of the latest discoveries about parallel universes. Scientists in Griffith University in Australia not only believe that parallel universes exist, but that they also influence one another through a subtle repulsion force. This so-called interaction makes it easier to understand quantum studies.
The multiverse theory and everything it entails is a challenge of quantum physics against the cause and effect laws, which come from logic. When faced with that bewilderment that brings down the entire scientific and rational construction of the last centuries, the theory of a coordinated action between universes is an apparently soothing simplification.
Stranger Things, The Cthulhu Mythos... Parallel universes inspiring sci-fi
Such stimulating ideas, of course, have come to inspire sci-fi creators. One of the first in exploiting the seductive idea of parallel worlds was the cosmic horror writer H.P. Lovecraft: the great attraction between the Cthulhu Mythos lies on creating imaginary, yet real spaces that blurred weird fiction with the possibilities of reality.
The efficiency of The Cthulhu Mythos lied on the fact that the author located the scenes in imaginary places which were supposedly connected to real, yet unknown, locations in the United States.
One of the most important masterpieces in that sense was Isaac Asimov's Gods Themselves, where he presents an alien conspiracy from a parallel universe to take away the energy of the Sun. Other authors have used this resource, such as Stephen King with The Mist, brought into cinema by Nick Darabont. Movies and TV shows have also used this resource; for instance, Paul W.S. Anderson in Event Horizon, or the Netflix hit show Stranger Things.
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