Multiverse theory, the theory that there are an infinite number of universes, is a controversial idea that, while attractive and full of promise, is practically unverifiable, making it difficult to grant it scientific status. Although multiverse theory is not currently recognized as science according to Kuhn and Feynman’s definition of science, its philosophical implications and possibilities remain important.
In the winter of 2014, the movie Interstellar was a box office success, attracting 10 million moviegoers. It was a stroke of genius to bring the concepts of relativity and multiverse theory of modern physics to the screen in a realistic way. These worldviews of the universe have been introduced to the public through various movies and novels, the most prominent of which is multiverse theory. Multiverse theory is the idea that there are an infinite number of universes, some similar to ours and some completely different, that exist and are progressing simultaneously. It’s a theory that has been largely dismissed as fiction by the general public, but recently some physicists have been able to prove it mathematically and claim that it’s no longer fiction. They say that the math is beautiful enough and that it can explain the universe well. Nevertheless, the classification of multiverse theory as a science is controversial because it suffers from a fatal flaw: it is an unverifiable theory.
Despite its popularity in both the scientific community and popular culture, multiverse theory remains controversial. While it’s theoretically appealing and holds a lot of promise, it’s practically unverifiable, which is why it’s hard for it to be recognized as science. There are three reasons why multiverse theory cannot be verified.
First, the premise of the multiverse itself is unprovable. Multiverse theory is designed to explain why the fundamental constants of nature are within such a narrow range that life can exist. It claims that there are an infinite number of other universes out there, made with all possible constants, and that ours is just the one that has the conditions to support life. For this theory to be valid, it would have to prove the existence of universes with different fundamental constants of nature than ours, which is nearly impossible.
Second, multiverse theory is not verifiable with current observational techniques. Multiverse theory is based on superstring theory, which claims to be valid through model-dependent realism. However, none of the natural phenomena predicted by superstring theory have been observed, including the multiverse. In his book “Not even wrong”, theoretical physicist Peter Voigt describes superstring theory as “a collection of theoretical physicists’ wishful thinking” because it has not produced results that can be tested experimentally. In other words, the observations required for model-dependent realism have not yet been made with current technology.
Third, multiverse theories are not testable. Even if the phenomena predicted by the multiverse theory are confirmed through the analysis of many observational data, it cannot be guaranteed that the phenomena are caused by the multiverse theory. In other words, unless the observations are compared with a universe other than ours as a control, the multiverse theory is not reliable.
From the above, it is clear that multiverse theory is not verifiable. However, theoretical physicists argue that the verifiability of a theory and the validity of a theory are two different things. Just because a theory is unverifiable doesn’t mean it shouldn’t be plausible. In his book The Many Universes, Brian Green argues that
“The mathematical system of classical mechanics deals with the position and velocity of everyday objects, from rocks and balls to the moon and sun, and so the theory has been tested by countless experiments. Classical electromagnetism, however, came about after a crucial phase of ‘abstraction’. In the 20th century, basic science became increasingly dependent on properties that cannot be touched or seen.”
As science moves from the past to the present, it inevitably derives theories based on increasingly inaccessible objects, and like relativity and quantum mechanics, which have been verified by observations, he believes that multiverse theories will soon be verified by advances in observational technology and differentiated verification methods that will lend credibility to the observations. Therefore, it is argued that even if the multiverse theory is currently unverifiable, it should not lose its scientific status as long as it has validity as a theory.
Of course, it may be unreasonable to reject a theory that is sufficiently mathematically verifiable as science just because it cannot be experimentally verified. However, the field of science has historically ensured rationality and verifiability. Two of the most powerful scientific theories of modern times, relativity and quantum mechanics, have gained widespread support and the status of science because observations have been consistent with the predictions of the theories. On the other hand, many theories that were theoretically sound, such as the pendulum theory, the spiral model of the atom, and the permanent steady state cosmology, lost ground because they failed to stand up to real-world verification. Historically, even if a theory is mathematically provable, if it cannot be verified, it is not recognized as science. But what if verification is not possible at all? If we were to categorize all theories as science because they are untestable and we don’t know whether they have failed or succeeded, we would be making a huge error in recognizing the afterlife and many religions as science. Therefore, the question of what constitutes “science” is crucial in determining whether multiverse theory falls within the category of science.
First, let’s look at Thomas Kuhn’s and Feynman’s definitions of what science is, and then we’ll look at multiverse theory. Thomas Kuhn defines science as a research endeavor that is organized to support the current paradigm. Currently, the paradigms that are universally accepted as valid are relativity and quantum mechanics. A new paradigm that has emerged to overcome the limitations of relativity and quantum mechanics is superstring theory. The question is whether the new paradigm is strong enough to overpower the old paradigm, and superstring theory is not yet strong enough to replace the old paradigm. Therefore, multiverse theory is not yet a science because it is not a research activity to support the old paradigm. Another interpretation is that Feynman, in his book “What is Science?”, defines science in terms of three items. First, a methodology and a stream of thought that can lead to new facts. Second, the derivation of certain rules based on observations. Third, the invention of new technologies based on those rules. Multiverse theory doesn’t fit into the first definition because we don’t yet know if there are other universes besides our own, and we can’t verify whether the theory itself is fact or fiction. It also doesn’t fit into the second definition because it deals with unobservable objects and its predictions have never been verified. Since multiverse theory is not a technology, it naturally does not fall under the third definition either. Therefore, multiverse theory cannot be said to fall under Kuhn and Feynman’s definition of science.
We have seen that multiverse theory is currently unverifiable, and we have seen from Thomas Kuhn and Feynman’s definition of science that unverifiable science cannot be treated as science. Therefore, we should not include multiverse theory in the category of science. Until it is verified, it should remain science fiction based on science.
As we have seen, the reasons why multiverse theory cannot be verified lead us to conclude that it does not belong in the category of science. This is important to maintain the standards of modern science, which emphasize scientific thinking and verifiability. The philosophical implications and possibilities of multiverse theory can remain an interesting and important topic of research, but it is difficult to give it scientific status when it cannot be verified.
