Parallel worlds, alternate dimensions, the multiverse – all these concepts have existed
in fiction for decades. Like other sci-fi ideas such as time travel and alien visitors, they've
become a cornerstone of the genre, something audiences can take in stride without much
explanation. But what’s the line between real life and fiction when it comes to multiple universes?
This is Unveiled, and today we’re answering the extraordinary question:
what does multiverse mean in fiction, and what does it mean in reality?
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‘Multiverse’ is the collective term for all the parallel universes in a given,
total ‘reality’ – which, in the case of fiction, is usually the entire world portrayed by its
creator. This creator could be one person, like Terry Pratchett, whose “Discworld” novels
occasionally utilize multiverses; or it could be an enormous company, like the two current world
leaders in multiverse storytelling, Marvel and DC. There’s often a practical reason behind this. In
superhero comic books, for instance, we’re getting close to having a century of continuity. With so
many different people working on so many comics and storylines for so long, and with storylines
that often conflict with each other, multiverses emerge as a natural way to unify all those
different ideas relatively easily. But multiverses don’t just exist in fiction, nor do they only
exist to reconcile problems in fictional worlds. They might be a way to reconcile problems in our
actual universe, too, problems like our current lack of a unified, grand theory of everything.
In theoretical physics, multiverses and similar ideas – like planes of existence that are
imperceivable to humans – emerge as a result of ‘theories of everything’. A theory of everything
is a hypothetical framework that would encompass all of physics - reconciling general relativity
and quantum mechanics. Both general relativity and quantum mechanics have been validated,
but are ultimately incompatible at certain scales. The most famous potential theory
of everything is arguably string theory. String theory is a little notorious for
its weirdness and complexity, postulating that particles are not single objects,
but long one-dimensional ‘strings’. Because they only exist in one dimension, versus humans who
exist across four dimensions, they’re deceptively simple, and appear to us like single ‘points’.
String theory has a major problem, however, a problem exemplified by M-theory, an even
WEIRDER version of string theory. M-theory unifies the five different versions of string
theory – all called superstring theories – into one. But it’s inelegant and requires
11 dimensions to work. Again, as far as we know, we’ve only got four dimensions in our universe:
three spatial – length, width, and depth – and one temporal, time itself. While four or five spatial
dimensions are ideas we can theorize about to an extent, when we’re trying to reach ELEVEN of them,
the challenge becomes incomprehensible. It's not just string theory that leads to such ideas,
either. Even cosmic inflation, something we know for a fact is happening, could be
a potential driving force behind the generation of parallel universes, too – the Big Bang may
have been THAT powerful. This endless inflation could even be creating various ‘bubble universes’,
which all expand in their own way as well, with everything coming from the initial singularity of
the Big Bang. But it's not likely we could ever reach one of these other bubbles. And perhaps
the reason it’s taking so long to come up with a theory of everything is that we’re not currently
accounting for these different universes, separate or related to our own as they may be.
In fiction, however, ideas like string theory aren’t usually taken into account when it comes
to the multiverse. The multiverse simply exists, often as a solution to inconsistent stories or
temporal paradoxes; rather than having time travel create a paradox, a parallel universe is created
to account for any differences. Getting back to an original universe or timeline can pose a
lot of problems, however. In reality, it’s also theorized that every single decision everybody
makes could spawn a parallel universe in itself, with almost no differences except for that one
thing - even if it does trigger a butterfly effect that could eventually, potentially lead to HUGE
changes overall. In this way, there are possibly infinite multiverses with infinite possibilities,
both in fiction and reality. Sometimes in fiction, parallel universes don’t even need
to abide by the same laws of physics, and the same could again be true in reality.
In real life, there are no omniscient fiction authors who know exactly how things will go and
how events lead on from each other. You’d have to have the knowledge of a god to be able to see
a butterfly effect in action in the real world, for example, beyond a few small instances of one
thing leading to another in your life. We just don’t know how situations could change based on
people making different decisions. There’s also the fact that fictional multiverses are, again,
often tied up with time travel. In the real world, most of the evidence still suggests that backwards
time travel is impossible, because you’d have to break the speed of light to manage it. So, a
mechanism to create a parallel universe to account for a temporal paradox might not actually exist.
In the here and now, there’s also no real reason why a new universe would NEED to be
made to account for different choices, even massive choices that have huge repercussions
for our species. And even in an existing multiverse, the different universes might
not have any real connection to each other at all. Maybe they’re not even infinite,
and there’s a set number of universes out there, none of which interact with each
other. We just don’t know, and that’s one of the biggest problems with multiverse theories. But,
in fiction, they’re almost always clearly linked; those problems are sidestepped.
In reality, and like many areas of hypothetical cosmology,
string theory included, it’s interesting to research, but there are plenty of naysayers.
Still, once black holes were believed by some to be far too weird to actually exist,
and THOSE people were proven wrong, so perhaps the multiverse will go the same way. But if the
multiverse and parallel universes do exist … could we - the humans of real life - travel
between them like the characters of sci-fi? There have arguably been hints toward yes.
In 2020, bizarre stories surfaced in many outlets claiming that NASA had discovered
evidence of a “parallel universe where time runs backwards”. What NASA was actually talking about
was the strange behavior of neutrinos in the Antarctic ice sheet. Nonetheless, the idea
of this baffling mirror-world took off in some circles. But still, if such a universe did exist,
traveling to and from it would probably be out of the question. How would a human from one universe
survive in a universe where the passage of time was reversed? It’s possible that if you tried to
cross into such a place, you’d perish immediately. Your body just isn’t built to travel backwards
through time, and likely neither would the bodies of anyone living in the mirror world be built to
travel forwards. The same could then be true for other universes, in general, even ones that don’t
have such drastic differences. Maybe it’s simply impossible to get between them, if they do exist
in reality, as you’d have to build a ship somehow capable of traversing boundaries that facilitate
the literal breaking down of reality. And, really, we know even less about how to do that than we do
about most other hypothetical concepts, like time machines or traveling through wormholes.
And finally, in fact and not fiction, many theories suggest that parallel universes would
be built from exotic matter instead of our own normal baryonic matter. And this could, again,
mean that we’re physically incompatible with these worlds. And, still, there are other problems, too,
such as even if we WERE able to reach a parallel universe, and even if it didn’t harm us… then
what if that parallel world doesn’t have any intelligent species of its own? What if the
intelligent species are unreasonably far away from whatever route we took into their world? We’ve
already not been able to find other examples of intelligent life in just our own universe, so what
really are the chances that we’d be able to find it in a different one? Unless a parallel version
of humanity is trying to break through into our world at the exact same time – which actually HAS
happened in fiction – it just doesn’t seem all that likely that we’d have much luck, in fact.
But what’s your verdict? Is the multiverse more science-fiction,
or could it yet be a true reality?
Ultimately, as far as we know, there’s no real way to prove the existence of the multiverse,
at present. And if our universe and another did ever collide,
then there’s a chance that neither would survive the encounter.
For us to verify its existence, another world would need to be observed,
and it remains one of the most theoretical areas of modern physics out there. All of
which means that it’s not surprising that it has become so popular in science fiction.
What do you think? Is there anything we missed? Let us know in the comments, check out these other
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