Even before the advent of Everett and his idea of multiple universes, physicists were at a dead end. They had to use one set of rules for the subatomic world, which is governed by quantum mechanics, and another set of rules for the large-scale, everyday world that we can see and touch. The complexities of moving from one scale to another twist the brains of scientists into bizarre shapes.
For example, in quantum mechanics, particles have no definite properties until no one is looking at them. Their nature is described by the so-called wave function, which includes all the possible properties that a particle can have. But in a single universe, all these properties cannot exist simultaneously, so when you look at a particle, it takes one state. This idea is metaphorically depicted in the Schrödinger's cat paradox - when the cat sitting in the box is simultaneously alive and dead, until you open the box to check. Your action turns the cat into a warm and lively one or a stuffed animal. However, scientists cannot agree with this either.
In the multiverse, you don't have to worry about killing the cat with your curiosity. Instead, whenever you open a window, reality splits into two versions. Unclear? I agree. But somewhere out there there may be another version of the event that just happened before your eyes. Somewhere there it did not happen.
It remains to find out what reasons scientists have found to tie this incredible theory to the facts.
So reality can be endless
In a 2011 interview, Columbia University physicist Brian Greene, who wrote Hidden Reality: Parallel Universes and Deep Laws of the Cosmos, explained that we are not entirely sure how big the universe is. It can be very, very large, but finite. Or, if you go from Earth in any direction, space can drag on forever. This is approximately how most of us imagine it.
Promotional video:
But if the cosmos is infinite, it must be a multiple universe with infinite parallel realities, according to Green. Imagine that the universe and all the stuff in it are equivalent to a deck of cards. Just like a deck of 52 cards, there will be exactly the same number of different forms of matter. If you shuffle the deck long enough, eventually the order of the cards will repeat the original order. Likewise, in an infinite universe, matter will eventually repeat itself and organize itself in a similar way. A plural universe, the so-called multiverse, with an infinite number of parallel realities contains similar but slightly different versions of everything that is, and thus provides a simple and convenient way to explain repetition.
This explains how the universe begins and ends
People have a special passion - and it is connected with the ability of the brain to form circuits - we want to know the beginning and end of each story. Including the history of the universe itself. But if the Big Bang was the beginning of the universe, what caused it and what existed before it? Is the universe waiting for the end and what will happen after it? Each of us has asked these questions at least once.
The multiverse can explain all of these things. Some physicists have suggested that the infinite regions of the multiverse could be called brane worlds. These branes exist in multiple dimensions, but we cannot detect them because we can only perceive three dimensions of space and one dimension of time in our own brane world.
Some physicists believe that these branes are piled together like slabs, like sliced bread in a bag. They are separated most of the time. But sometimes they do. In theory, these collisions are catastrophic enough to cause repeated "big bangs" - so that parallel universes start over, over and over.
Observations suggest multiple universes may exist
The European Space Agency's Planck Orbital Observatory collects data on the cosmic microwave background, or CMB, a background radiation that has been glowing since the early and hot days of the universe.
Her research also led to possible evidence for the existence of a multiverse. In 2010, a team of scientists from the UK, Canada and the United States discovered four unusual and unlikely circular patterns in the CMB. Scientists have suggested that these marks may be "bruises" that remained on the body of our universe after colliding with others.
In 2015, ESA researcher Rang-Ram Hari made a similar discovery. Hari took the CMB model from the observatory's celestial image and then removed everything else we know about it - stars, gas, interstellar dust, and so on. At this point, the sky should have been mostly empty, apart from background noise.
But it didn't. Instead, at a specific frequency range, Hari was able to detect scattered spots on a map of space, regions that were about 4,500 times brighter than they should have been. Scientists have come up with another possible explanation: these areas are prints of collisions between our universe and the parallel.
Hari believes that if we do not find another way to explain these marks, "we will have to conclude that Nature, after all, can play dice, and we are just one random universe among many others."
The universe is too big to rule out the possibility of parallel realities
There is a possibility that multiple universes exist, although we have not seen parallel realities, because we cannot deny its existence.
This may sound like a clever rhetorical trick at first, but think about this: even in our world, we found many things that we never knew existed, and these things happened - the 2008 global crisis is a good example. Before him, no one thought it was possible at all. David Hume called this kind of event "black swans": people will think that all swans are white until they see black swans.
The scale of the universe allows us to think about the possibility of the existence of multiple universes. We know that the universe is very, very large, possibly infinite in size. This means that we will not be able to detect everything that exists in the universe. And since scientists have determined that the universe is about 13.8 billion years old, we can only detect the light that has managed to reach us during this time. If a parallel reality is farther than 13.8 light years away from us, we may never know about its existence, even if it exists in the dimensions we distinguish.
Multiple universes make sense in terms of atheism
As Stanford University physicist Andrei Linde explained in a 2008 interview, if the physical world obeyed slightly different rules, life would not be able to exist. If protons were 0.2% more massive than they are now, for example, they would be so unstable that they would decay into simple particles instantly without the formation of an atom. And if gravity were a little more powerful, the result would be monstrous. Stars like our sun would be squeezing tight enough to burn their fuel in a few million years, preventing planets like Earth from forming. This is the so-called "fine-tuning problem".
Some see this precise balance of conditions as proof of the participation of an omnipotent force, a supreme being who created everything that greatly anger atheists. But the possibility of the existence of a multiverse, in which this force will simply be in a separate reality with all the factors necessary for life, suits them perfectly.
As Linde said, “For me, the reality of multiple universes is logically possible. We can say: perhaps this is some kind of mystical coincidence. Perhaps God created the universe for our good. I don't know anything about God, but the universe by itself could reproduce itself an infinite number of times in all possible manifestations."
Time Travelers Can't Break History
The popularity of the Back to the Future trilogy has led many to get carried away with the idea of time travel. Since the film came out on screen, no one has yet developed a DeLorean capable of traveling back and forth in time, decades or centuries. But scientists believe that time travel may be at least theoretically possible.
And if possible, we could find ourselves in the same position as the main character of "Back to the Future" Marty McFly - at the risk of unintentionally changing something in the past, thereby changing the future and the course of history. McFly accidentally prevented his parents from meeting and falling in love, thereby successfully removing himself from family photographs.
However, a 2015 article suggested that the existence of the multiverse does not make such hassle mandatory. “The existence of alternative worlds means that there is no single chronology that can be violated,” wrote Georg Dvorsky. On the contrary, if a person goes into the past and changes something, he will simply create a new set of parallel universes.
We could be a simulation for an advanced civilization
All of these topics about parallel universes that we have discussed so far have been extremely interesting. But there is something else interesting.
In 2003, philosopher Nick Bostrom, director of the Institute for the Future of Humanity at Oxford University, wondered if everything we perceive as reality - in particular, our separate parallel universe - could be just a digital simulation of another universe. According to Bostrom, it would take 1,036 calculations to create a detailed model of all of human history.
A well-developed alien civilization - creatures whose technological level will make us look like cave dwellers of the Paleolithic - could very well have enough computing power for this all. Moreover, modeling each individual living person will not require any completely dizzying electronic resources, so there can be much more real creatures modeled on a computer.
All this could mean that we live in a digital world, like in the movie "The Matrix".
But what if this advanced civilization is itself a simulation?
People have thought of multiple universes since time immemorial
It will be extremely difficult to prove this. But here one cannot but recall the old sayings that are attributed to either Picasso or Susan Sontag: if you can imagine something, it must exist.
And there is something in this. After all, long before Hugh Everett sipped his cognac, many people throughout human history imagined different versions of the multiverse.
Ancient Indian religious texts, for example, are filled with descriptions of many parallel universes. And the ancient Greeks had a philosophy of atomism, which argued that there is an infinite number of worlds scattered in the same infinite void.
In the Middle Ages, ideas of multiple worlds were also raised. The Bishop of Paris in 1277 argued that the Greek philosopher Aristotle was wrong in saying that there is only one possible world, because this casts doubt on the almighty power of God to create parallel worlds. The same idea was revived in the 1600s by Gottfried Wilhelm Leibniz, one of the pillars of the scientific revolution. He argued that there are many possible worlds, each of which is endowed with a separate physics.
All this fits into our scheme of knowledge about the Universe
It will be extremely difficult to prove this. But here one cannot but recall the old sayings that are attributed to either Picasso or Susan Sontag: if you can imagine something, it must exist.
And there is something in this. After all, long before Hugh Everett sipped his cognac, many people throughout human history imagined different versions of the multiverse.
Ancient Indian religious texts, for example, are filled with descriptions of many parallel universes. And the ancient Greeks had a philosophy of atomism, which argued that there is an infinite number of worlds scattered in the same infinite void.
In the Middle Ages, ideas of multiple worlds were also raised. The Bishop of Paris in 1277 argued that the Greek philosopher Aristotle was wrong in saying that there is only one possible world, because this casts doubt on the almighty power of God to create parallel worlds. The same idea was revived in the 1600s by Gottfried Wilhelm Leibniz, one of the pillars of the scientific revolution. He argued that there are many possible worlds, each of which is endowed with a separate physics.
All this fits into our scheme of knowledge about the Universe.
Ilya Khel