If you want your sci-fi story to sound more scientific and believable, try adding the word multiverse. For example, the famous Marvel is particularly fond of the concept of the multiverse, whether it is Spider-Man or Doctor Strange, can not escape the multiverse routine.
Poster for the Marvel movie Doctor Strange 2: Crazy Multiverse. (Photo: Marvel Studios)
So, which of these strange ideas are borrowed from science, and which are pure fiction?
Simplified Multiverse: A Vast Universe
Will there be other Earths? Could there be other people who look a lot like us and live on a planet that looks like ours? This is scientifically possible, because we have no idea how big the universe really is.
According to cosmological principles, the distances we can see are actually limited, and the observable universe contains space spanning tens of billions of light years, but we don't know how much space is beyond the scope of light.
If there is more space beyond that, which is also filled with galaxies, stars, and planets, the possibility of another Earth is much greater. With enough space and enough planets, the very small possibilities become possible.
In addition, in fictional stories of the multiverse, the protagonist often needs some superpowers to travel between Earth and "other Earths", such as Doctor Strange's spells and magic, which in some ways also happen for a reason.
According to Albert Einstein, we can't travel through space faster than the speed of light. While it's scientifically possible to travel through the universe in more exotic ways, such as wormholes, we don't yet know how to make them, and they don't seem to appear naturally in the universe either. And there's no reason to think that they would happen to connect us to another Earth, rather than randomly appearing somewhere in an empty space.
True Multiverse: Changes in the Laws of Nature
The multiverse of the sci-fi world may seem crazy, but from a scientific point of view, it is simply too gentle, too normal, too familiar.
That's because the fundamental components of our universe, including quarks, electrons, light, and so on in protons and neutrons, can emerge amazing creations, such as human life. Your body is an amazing machine that collects energy, processes information, and even builds miniature machines to repair itself.
However, physicists have discovered that this ability to make life forms possessed by the fundamental building blocks of our universe is extremely rare. If electrons are too heavy, or the force that binds atomic nuclei together is too weak, things in the universe can't even be "glued" together, let alone appear as wonderful as living cells or even life.
How did our universe get the right "recipe"? Perhaps, we are just lucky enough to win the cosmic lottery. Perhaps, on a much larger scale than we can see, the rest of the universe has different fundamental elements.
In any case, our universe is really just one of the options, a particularly fortunate option, and the many other multiversees are likely to be the ones that "didn't win the lottery."
This is the scientific multiverse, which is not simply more "our universe", but a universe with different basic components. Most of them are lifeless, and only in very, very, very rare cases will combinations suitable for life forms appear.
In contrast, the multiverse in science fiction simply rearranges the familiar atoms and fundamental forces (plus a little magic) in our universe. This is not enough.
Cosmic inflation and the Big Bang
To explore the multiverse scientifically, one has to go back in time to the far-reaching past of our universe. One idea, known as cosmic inflation, holds that in the first moments of the universe's birth, it expanded very rapidly.
But how do you make a universe expand so rapidly? The answer may be a new type of energy field that controls the universe's first moments, causing rapid expansion before giving it all the dominance to more familiar forms of matter and energy, namely protons, neutrons, electrons, light, and so on.
Cosmic inflation could create a multiverse. In the simplest way to understand, according to this idea, most of the space is expanding, expanding, and the size is constantly doubling from moment to moment. On each "cosmic island," new energy fields spontaneously and randomly convert energy into ordinary matter with extremely high energies, releasing what we now think of as the Big Bang.
If these high-energy disrupt and reset the fundamental properties of matter, then each cosmic island can actually be considered a new universe with different properties. In this way, we have created a multiverse.
So, does the multiverse really exist?
In the cycle of the scientific method, the multiverse is in the exploratory phase. If it's true, we already have an idea to explain something.
But as Professor Alex Verlenkin, one of the founders of the multiverse theory, said in his book What is the Multiverse, "In the face of these ultimate problems of the universe, cosmologists and detectives have no advantage over each other, relying on circumstantial evidence to infer the unobservable part of time and space through measurements of the observable universe." These restrictions make 'the exclusion of reasonable doubt' more difficult". The crux of the matter is that we also need more direct and conclusive evidence.
Interestingly, some new cosmological developments have been shocking enough that seemingly contradictory descriptions have been combined to describe our universe, which may be both bounded and boundless, that it is changing and static, that it is eternal, but that it has a beginning.
"It's crazy, crazy enough to be true." Nils Bohr said.
#创作团队:
Compile: M ka
Typography: Wenwen
#参考来源:
https://theconversation.com/the-multiverse-is-huge-in-pop-culture-right-now-but-what-is-it-and-does-it-really-exist-181781
Alex Verrenkin, What is the Multiverse, CITIC Publishing Nautilus, January 2021
#图片来源:
Cover image: Silver Spoon, Wikimedia Commons
首图：Thomas Hawk, Flickr, CC BY-NC