The idea that there could be other universes beyond our own , evolving in parallel or as part of a multiverse, is over two thousand years old . However, the conception that we have today arose as a result of a possible interpretation of quantum physics . What was proposed as a mere theoretical game, a mathematical curiosity without further importance , has become one of the most popular scientific concepts among those who are not professionally dedicated to science. Such has become this popularity that the Marvel franchise, probably the most successful (in terms of money raised, at least) in the history of cinema, has dedicated the plot of more than one film to this concept.
With the premiere of the latest installment of the Marvel Cinematic Universe, the studio has given authentic prominence to this concept, making it the common thread of the plot of the film entitled Dr Strange: Into the Multiverse of Madness (2022). In the film we see how Stephen Strange seems to disrupt the normal functioning of our universe , making it coincide with other instances of it, other parallel universes within the multiverse. This allows him to explore the limits of his powers and of reality itself.
But does what they propose make any sense? Or should we understand it as simple fantasy? After all, Marvel movies, especially those released in the last few decades, tend to try to justify their plot devices from science , albeit vaguely. In the Avengers saga, for example, mention was made and considerable weight was given to concepts of quantum mechanics or those related to time travel . On many occasions this simply translates into using scientific-sounding words to describe their plans , rather than explaining or applying any knowledge accepted by current science.
The concept of the multiverse, or of an infinity of universes that coexist in some way, first emerged in ancient Greece . The defenders of atomism believed that there were infinite atoms occupying an infinite vacuum for an infinite time . These collided and bounced, giving rise to infinite worlds, among which ours was one more of that incomprehensible quantity. These ideas fell into disuse but were not completely forgotten, and we can find mention of them during the Middle Ages and well into the 20th century , during which they took on a new meaning as a result of the increasing development of quantum mechanics . This mechanics includes the concept of superposition , in which a certain quantum system is capable of occupying a state that would seem to be the mixture or the sum of several different states .
To make sense of this, it has been proposed, among other things, that the various possible states that make up the state of a superposition system would each correspond to the state of one of several universes exactly identical except for that discrepancy . For example, in the famous Schrödinger’s cat thought experiment, in which according to quantum physics the cat could exist in a superposition of “alive” and “dead” states . The multiverse interpretation would be that the cat exists in both states, but in different universes . However Schrödinger proposed this example precisely to show how macroscopic systems cannot be governed by quantum laws .
In this way, every time a quantum system finds itself in superposition of states, we would really be seeing a consequence of the existence of this multiverse . However, this hypothesis is very unscientific. Although the superposition was a kind of window to other supposed universes, the truth is that there is no physical way to access the slightest information about them . If we interact with one of these superimposed systems, even in the most subtle way (by causing a photon or other particle to hit it), we will cause it to collapse into one of the many (or even infinite) states it could be in. Appear. That is, even if in our particular universe Schrödinger’s cat turned up dead, we would have no possible way of contacting (or even observing) the universe in which the cat has survived the experiment .
So if we can’t interact in any way with these parallel universes, and they can’t interact with us, what does their existence give us? If we do not have access to them, it means that the hypotheses that explain the multiverse cannot be tested , neither to deny them nor to accept them. These explanations sometimes seem to be closer to theological approaches than to scientific ones. The multiverse, at least as we conceive it today, requires a leap of faith on our part, as it has no tangible or measurable consequence on our reality.
The problem of course is not in the exoticness of this theory or in the counterintuitiveness. Quantum mechanics or relativity have consequences that, to our ape brain, might seem illogical. However, these theories make predictions about the world around us that can be tested and that, in addition, have been successful. An anything-goes theory, such as the multiverse, has little explanatory power, little ability to describe and make sense of the workings of the universe. Referring to the existence of infinite universes to try to make sense of the peculiarities of the universe [link to “Why does the universe (exactly) expand?”] that we inhabit would be as unjustified as invoking a mythological creator being.
In short, if we have to answer the question that gives the title to this article in a few words, the answer would be “yes, please” for those who are dedicated to creating science fiction stories and it would be “it doesn’t matter” for the vast majority. of those who dedicate themselves to thinking about these issues. The most honest answer, however, is probably “we have no way of knowing.”
REFERENCES:
Ellis, J, Silk, 2014, Scientific Method: Defend the Integrity of Physics, Nature. 516 (7531), doi:10.1038/516321a
