1. Introduction

The exploration of the multiverse has become a subject of profound interest among scientists and philosophers alike. Within the realm of cosmology, the multiverse theory postulates the existence of a vast ensemble of parallel universes, each operating under its own set of physical laws and conditions. This essay embarks on an intellectual journey into the intricacies of the multiverse, delving into its theoretical underpinnings, implications, and the philosophical and scientific inquiries it engenders. It also underlies the potential ramifications in expanding the understanding of reality, and the intricate questions it raises at the intersection of science and philosophy; at the same time, it aims to suggest that such existence is a means to an end rather than an end in itself. It opens the door of ponderance in many fields rather than giving a direct answer to the uncertainties that exist in the philosophy of science and our general understanding of the universe. Though this exploration extends and branches into several fields, the question will ultimately guide scholars back to reflect upon what is meant by humanity and how such belief in the multiverse would affect the human existence.

This essay argues and justifies the belief of a multiverse, though it may remain to be observationally unproven. From a philosophical lens, a multiverse theory is able to resolve the present coincidences like the fine-tuning problem. Moreover, elucidating the interplay between a concept that resides at the intersection of science and philosophy and its relevance to daily existence entails comprehending its implications in regard to morality, ethics, and religion. This endeavor involves questioning the foundational assumptions in these domains and establishing connections to everyday life.

2. Contextual background

To assess how likely a multiverse is to exist, it is first necessary to understand what is meant by that term. Several competing multiversal models have been developed.[1] The multiverse might be comprised of an infinite number of universes sitting in regions of space far beyond the boundaries of the known universe, as envisaged by Alan H. Guth in the inflationary scenario.[2] Alternatively, it could be made up of universes that exist at different points in time, as per the cyclic model of Paul J. Steinhardt and Neil Turok.[3] It is also possible that alternate universes exist in the same space but in a different branch of the quantum wave function, as advocated by Hugh Everett.[4]

Perhaps the most scientifically accepted idea of a multiverse is tied to the concept of inflationary cosmology. Following the Big Bang, the universe expanded rapidly and exponentially in a process called cosmic inflation. The mechanisms governing this process remain mysterious, but one of the best explanations developed so far relies on eternal inflation. That model suggests that the universe ceases to expand in certain bubble-like pockets of space. These pockets then develop into new universes because spacetime continues to expand away from them, leaving them isolated. Infinite universes are generated because the space between the bubbles, which is still inflating, makes room for more bubbles to form. Because this process has occurred since the Big Bang and will continue to occur, the universe humans inhabit represents just one out of an infinite multiverse of bubbles. These bubbles would not all share the same properties as our own — each universe that emerges would do so with its own laws of physics, collection of particles, arrangement of forces, and values for fundamental constants.[5]

Another compelling multiverse theory relies upon Everett’s many-worlds interpretation of quantum mechanics, a model arising from a mathematical explanation of how matter behaves. Quantum physics is built on the idea that many properties of matter – such as location and speed – are not pre-determined but random. Quantum mechanics suggests that multiple states of existence for subatomic particles are possible simultaneously; a "wave function" encapsulates all such possibilities. When any given particle is observed or measured, the wave function "collapses" into a single reality.[6] The many-worlds interpretation of this phenomenon suggests that measurements taken are not the only values possible. Rather, as the fundamental ontology of the physical world rests on the quantum state, all different branches of this quantum state represent different classical worlds. This approach gives good and indirect evidence for the existence of such a quantum mechanical multiverse.[7]

3. Approaching the Multiverse Problem

The basic problem of a multiverse proposal rests not on the uncertainty of its existence, but on proving this theory altogether in the scientific field. This ties into the problem of the cosmic visual horizon. Due to the speed of light, all the parallel universes lie outside the observable horizon and will remain beyond observation, regardless of technological advancements.[8] Thus, the proposal of a multiverse is beyond falsifiability, and no conventional means would work to prove it.[9] There are even strong objections arguing that the multiverse shouldn’t be considered science, like the dictum of Karl Popper, which held that a theory should be falsifiable to be scientific.[10]

Though there is no hope of testing it observationally, of the diverse number of multiverse theories, all suggest the spacetime that has been observed is not the only reality. Theoretically, if cosmic inflation and quantum field theory both hold true, then the existence of some sort of multiverse seems likely. But as a concept that lies on the edge of science and philosophy, its existence matters not in the disputes of the scientific world but in a perceptional supposition that grants individuals the freedom to imagine all the possible implications that arise from this idea.

4. Implications

4.1. Epistemology

The uncertainty surrounding the multiverse proposal is not a misfortune; rather, it compels individuals to accept its undeterminable nature and challenge the traditional notions of scientific inquiry by positing the existence of unobservable and inaccessible parallel universes. This inquiry extends epistemologically as such existence questions the very definition of scientific knowledge and creates space to redefine it. From the ancient Greeks, knowledge has been classically defined to be a “justified true belief.”[11] In this context, the multiverse, for now and in the near future, will remain to be “unjustified” due to the lack of observational evidence. While the multiverse is disputed regarding its status as knowledge, its existence should not rely solely on empiricism when there are sufficient reasons to believe in such existence.

From an anthropic lens, the universe is fine-tuned for life and a multiverse solves the fine-tuning problem. Out of the infinite possible ways the values of the fundamental constants can range from, the physical constants in the universe humans inhabit have just the right values needed to allow complex structures and living things to thrive, like the mass of electrons, the strength of gravity, or the lifetime of neutrons. Viewing the universe as one among the infinite universes provides a tidy explanation for this apparent coincidence when tracing back to the early history of the universe, where individual universes are influenced by random fluctuations of quantum mechanical origin. Our universe appears to be one of the logically possible universes and to be in the conditions that make it viable for life to emerge.[12]

Another way to see the fine-tuning problem is to attribute this apparent coincidence to the contemplation of an observer, as the anthropic principle described. It suggests that the reason the observed universe has specific values for fundamental constants is that conscious observers can only exist in a universe that allows for their existence. In other words, if the values were different, the emergence of intelligent life would not be possible, and humans would not exist to contemplate fine-tuning. Therefore, it is not surprising that humans find themselves in a universe with the necessary conditions for life. It is a consequence of the selection bias imposed by the existence of conscious observers, resolving the fine-tuning problem. [13] The anthropic principle further brings attention to the fact that observations and scientific theories are inherently limited by the conditions and properties of the universe. It challenges scientists to consider whether the current understanding of the fundamental laws of nature is a result of a selection bias and whether it can be generalized to all possible universes.

Exploring both the anthropic principle and the fine-tuning problem encourages scholars to reflect upon these principles, as they examine the lens of a multiverse theory and contemplate the formation of the universe and its significance in relation to our place within it. To believe in the existence of a multiverse is to push the limits of knowledge. It prompts reflections in better understanding human’s role in the universe, the causes for existence, and potential reasons the constants and physical laws are the way they are. These beliefs and inferences are philosophically valid. And the exercise of the imagination is an equally valid way of producing knowledge that roots itself in beliefs. Under such a controversial topic, the difference between knowledge and belief can become blurry, as the pursuit of knowledge in this instance is beyond the application of empirical methods. It is the belief in a multiverse that determines the extent of knowledge that can be obtained; thus, the belief itself should be reconceptualized in fresh light to redefine knowledge.

4.2. Ethics

Aside from epistemological considerations, there are ethical motivations for invoking a multiverse. A major debate in ethics relates to the concept of free will. Various arguments have been posited for and against determinism. The most theoretically compelling version of hard determinism is grounded in the laws of physics: it suggests that whatever occurs can be predicted by applying knowledge of physical laws, which are universal and immutable. The implication is that every decision individuals make is predetermined because each comes in response to various predictable interactions between forces and matter. The only strong argument against this model is tied to a non-multiversal interpretation of quantum randomness, which suggests that subatomic outcomes cannot be predicted since the same laws generate different results. Individuals are therefore unable to predict which decisions will be made by resolving all equations in advance. However, believing in Everett's multiverse and accepting this interpretation, which assumes that all possible outcomes of quantum events occur in different parallel universes, leads to the conclusion that quantum interactions are not random. Consequently, the concept of free will would be negated, as there would exist no capacity to make independent choices. Life would be fundamentally devoid of purpose, as every decision made would be replicated in an infinite number of alternate ways across parallel universes.

It is possible that this kind of pointlessness would cause an increase in immoral activity. This is because, when people stop believing they are free agents, they stop seeing themselves as blameworthy for their actions. However, in practice, this pointlessness would be unlikely to change human behaviour. Multiverses are not the only threats to the idea that life has meaning. The unplanned, evolutionary development of human beings and the inevitability of deaths both suggest that existence is devoid of any essential meaning. However, having no essential meaning does not mean having no meaning at all.

Albert Camus’s work on absurdism demonstrates a distinction between essential and acquired meaning; his model frames human experience as the search for rational meaning in a fundamentally irrational world.[14] He uses the myth of Sisyphus to explain how meaning can nonetheless be generated. In the myth, Sisyphus is punished to roll a boulder up a hill for eternity. He never quits, according to Camus, because he accepts the absurdity of his task but derives his own meaning from it. Every time he rolls the ball up the hill can be configured as a spiteful victory against Zeus. He sticks at it because he imbues it with value. At the end of the Myth, Camus says that we have to ‘imagine Sisyphus happy’. It is a failure in scale to say life is meaningless because humans make meaning on a small, personal scale, whereas the world is absurd only on a global, or cosmic, scale. To perceive oneself as one of the infinite iterations is to view humanity from a different lens and to derive meaning for who we are in this universe.

4.3. Religion

From a religious Christian perspective, an infinite multiverse fundamentally complicates ideas about God. Christians see God as an omnipotent, omnibenevolent being.[15] Were there infinite multiple universes, God could not be all-loving since every possible outcome would occur, including many involving great suffering. Some universes would have less suffering than ours, while others would have more deaths, grief, distress, loneliness, and illnesses. If God were responsible for them all, the concept of omnibenevolence, as traditionally understood, would be called into question. Humans could not be living in the best of all possible worlds, as Leibnitz suggests.[16] If kindness is defined only as what God does throughout every universe – not some idea independent of him – and many of these universes have intense amounts of what we deem suffering, then our understanding of kindness becomes totally relative. If there were infinite versions of universes with every possible outcome occurring, God could not be omnipotent because he could not create a universe where an event would not happen, or a decision had not been made.

On the individual level, such proof would undermine the idea of having a personal relationship with God. If there are infinite versions of any given person, the extent to which any one version engages with God becomes infinitesimal. Moreover, if infinite versions of an individual exist simultaneously, and each iteration represents the sum of all possibilities, an individual would acquire godlike attributes. However, despite these conceptual challenges, the drive to seek divine consolation may still continue whether or not individuals believe in such existence.

From the perspective of a Buddhist, the multiverse existence may not affect any of the core beliefs in the religion or the practices of individuals. Seeing human life as a cycle of suffering and rebirth and believing in the process of enlightenment to escape the cycle casts no effect on the present existence and experience of whether or not infinite iterations of an individual exist. Suffering is inevitable according to the Buddha, and it is created by desire, but could be avoided through enlightenment. This would not be affected by the belief in a multiverse since human suffering will not be reduced and cannot be avoided simply because of the belief in other versions of each individual. The experiences across different universes are irreplaceable. That said, such belief will not affect the present experiences in any way. The Buddhists will still be likely to practice meditation and engage in ethical conduct the way they do to act for goodness for future rebirths. This thought experiment will likely redirect attention back to the current living, as one acknowledges that what matters the most are the present experiences.

The belief in a multiverse and its implications in different religions can vary greatly; for Christianity, it may challenge the most fundamental conceptions of the divine and question the creation of universes as a part of the multiverse, while for other religions like Buddhism, it is merely a thought experiment to ponder upon, at most touching upon the afterlife for individuals to question where their rebirth would put them in – to be in the present universe or to be a part of a completely new system.

5. Conclusion

In this paper, the multiverse problem has been approached from a new angle: in the grey area between science and philosophy, between knowledge and belief. It has proposed a new way of understanding knowledge when ideas like the multiverse lie beyond the conventional way of classification and understanding. To believe in its existence is a prerequisite to obtaining new knowledge; to accept the uncertainty that revolves around it is what grants imagination to extend into realms of philosophy and religion. Lastly, the exercise of imagination along with such belief enables individuals to personally relate and gain a new understanding of ethics and religion, more broadly, in relation to the origin of humanity itself. Acknowledging the universe among the infinite possibilities entails recognizing the multitude of potential implications it can entail. This, once again, emphasizes that the only aspect within one's control is the unaffected present. Therefore, regardless of the existence of infinite iterations of individuals or the empirical proof of a multiverse, the breakthroughs in thought are undeniable.

The idea of a multiverse will continue to be debated in the scientific community and among philosophers. For the science world, such understanding is likely to spur breakthroughs in both methodology and theoretical understanding in the search for a unifying equation of the observed reality, like the presently focused research on string theory and quantum gravity. For philosophers, this discussion will likely continue and emerge around other topics like the nature of causality, the potential of parallel or alternate histories, and the implications for concepts such as determinism and free will. Last, as a concept that engages great minds in science and humanities, it calls for an interdisciplinary collaboration between physicists, mathematicians, philosophers, and cosmologists, which may lead to fruitful exchanges in interdisciplinary research.

Acknowledgements

I would like to express my sincere gratitude to my supervisors who helped me throughout the process for their invaluable guidance, expertise, and support. I would also like to extend my appreciation to my family and friends for their love and encouragement throughout this endeavor. Their belief in my abilities and their constant encouragement were a source of motivation and inspiration.