Is the multiverse theory plausible? What is the multiverse?The multiverse is a topic which has attracted a great deal of attention in the past few decades, particularly in the fields of theoretical cosmology and philosophy. The notion of the multiverse has actually been employed in a number of distinct ways, and it's important to distinguish between them. This article will briefly consider three of the more common uses of "multiverse," and their implications for a Christian worldview.
The first common use of the term "multiverse" occurs in the context of "possible worlds" semantics, a technique used in the field of philosophy and modal logic. Essentially, a "possible world" is an artificial way of imagining how things in the real world (the "actual world") might have been different from how they in fact are. For example, we would say that in the actual world, I am currently 5 feet and 10 inches tall, but there exists a possible world in which I am actually 6 feet and 4 inches tall. Of course, we don't really mean that there is another universe in which I am 6 feet and 4 inches tall; we just mean that it is hypothetically possible for me to have been taller than I actually am. Put this way, the "possible worlds" semantics affords philosophers a useful way of discussing arguments involving how things could have been different from how they are (i.e., what if I were 6 feet and 4 inches tall instead of 5 feet and 10 inches tall?). The precise reason that the notion of a "possible world" is useful in this context does not need to concern us here. The crucial point to observe here is that in general, no one claims possible worlds are the same as the actual world. So "possible worlds" semantics, while being extremely useful in the fields of philosophy and modal logic, implies little about the actual world. In this sense, therefore, "possible worlds" do not really correspond to a multiverse at all; they are just a "verbal trick" which allows philosophers to tackle otherwise difficult problems in the field of philosophy. Nevertheless, the apparent similarities between "possible worlds" and other uses of "multiverse" mean that we must be careful to avoid confusing them with one another.
The second sense of "multiverse" that I want to consider here is sometimes known as the "many-worlds interpretation" of quantum mechanics. Simply stated, this interpretation of quantum mechanics attempts to address the fundamental randomness which is apparently inherent in the outcome of any given microscopic (i.e., quantum mechanical) experimental measurement. In short, rather than being able to predict what the precise outcome of any such measurement would be, physicists can only compute the probability of one outcome versus another. This state of affairs is quite different from ordinary (or classical) mechanics, in which physicists can make precise predictions for the results of experimental measurements. Indeed, this fundamental difference between quantum and classical mechanics has puzzled physicists ever since quantum mechanics was first invented in the early 20th century. In technical terms, quantum mechanics introduced a fundamental indeterminism into the laws of physics which was not present in the older, classical picture of the world.
To help explain the confusingly probabilistic nature of quantum mechanical processes, some physicists attempted to partially restore the determinism of the classical picture by claiming—without evidence—that every possible quantum mechanical outcome was in fact realized in newly created universes at every moment. In other words, every time a quantum mechanical measurement was made, our universe would split into a huge number of new universes, each corresponding to a different potential outcome of that measurement. In this sense, every possible quantum mechanical outcome is realized in some universe.
Not surprisingly, this idea is fraught with a huge number of conceptual problems, and hardly anyone in the world of physics takes it seriously at all, although this unfortunately doesn't stop many non-physicists from taking the notion of many-worlds quantum mechanics and inventing even crazier ideas which can only be called science fiction. The many-worlds hypothesis is also inconsistent with a biblical worldview, since it would appear that there exists one of many, many other universes in which no human being has ever sinned, for example, or in which Christ was never raised from the dead. Clearly, if true, this interpretation of quantum mechanics would have severe theological implications for Christianity. Fortunately, however, as already indicated, the many-worlds interpretation is not really taken seriously by most practicing physicists, and moreover, there is not a shred of experimental evidence in its support. Christians (as well as non-Christians) would do well to discard this interpretation without hesitation.
The final—and most common—use of the term "multiverse" stems from the field of theoretical cosmology, and refers to the hypothesis that many universes, very similar to ours, exist outside of our own universe; the collection of all existing universes is thus known as the "multi-verse." We can roughly define the "multiverse" in the following way: essentially, the multiverse is a collection of universes, where each universe in the collection has the potential to be much like our own in some ways, but different in other ways. For instance, different universes within the multiverse might differ in their strength of gravitational force, but be identical in other respects. Although this scenario is allowed by physics, there is absolutely no direct evidence for the existence of the multiverse, as used in this context.
So why has the notion of the multiverse attracted so much attention in recent years, if there is no real evidence to support it? To understand this, one first needs to realize that the properties of our universe—such as the strengths of the fundamental forces of nature, for example—appear to be fine-tuned to support life: if the gravitational force were much stronger, for instance, stars would burn much more hotly and quickly than they do today, making life highly improbable, but if gravity were much weaker, then stars would be too cool and would never produce the heavy metals needed to form life. In other words, there is not much "wiggle room" for the gravitational force, and too much variation in either direction would lead to a universe incapable of supporting life. On the atheistic view, then, our universe's obvious capacity for supporting life comes as quite a surprise—almost as if Someone had designed our universe to be capable of harboring life. If it's possible for the strength of the gravitational force to fall within a wide range of values, and our universe just happens to possess a gravitational force which falls into the much narrower band of life-supporting values, it becomes clear that the existence of life on earth is more than a mere accident. This argument is only strengthened when we broaden our scope to all of the features of physical laws in our universe, not just the gravitational force; when we do this, we realize that the chance of our universe on its own being capable of supporting life appears to be astronomically small, if not impossible.
On the other hand, the existence of life in our universe can be rendered much less surprising if there are many universes instead of just one, since this means that there are many more opportunities for a universe to possess the right strength of gravitational force to support life, than if only one universe actually existed. Think of it this way: imagine that we are playing the lottery, such that there are a billion lottery tickets available, but only one of which corresponds to the winning number. If you and I are the only two people in the world, and we choose just one such ticket, the odds are pretty good that we will not manage to choose the winning ticket. On the other hand, if we purchase all the available lottery tickets, we are guaranteed to stumble upon the winning lottery ticket sooner or later. The point is, the more tickets we buy, the better our chances of finding the winning ticket.
This is exactly what the multiverse allows atheists and skeptics to accomplish: it's like "buying" more universes (i.e., lottery tickets) until one ends up with one universe (i.e., the winning ticket) which is capable of supporting life. In this way, the existence of life can plausibly be viewed as an accident, and the appeal to an Intelligent Designer or Creator (ostensibly) becomes superfluous. It's for this reason that the concept of the multiverse has received so much attention in recent years.
Of course, it's crucial to emphasize here that there is no unambiguous evidence whatsoever for the existence of the multiverse—it is entirely a hypothetical construct developed for the purpose of circumventing the need for a Creator to explain the existence of life on earth. We should also point out that the multiverse theory is still left with the problem of who or what instigated the "lottery" to begin with. And even if the multiverse were one day to be discovered, this would mean nothing for the existence of a Designer, who is capable of creating a "multiverse," just as easily as He is capable of creating the universe we observe around us. Thus, the notion of the multiverse, although commonly raised as an objection to Christianity in the context of theoretical cosmology, poses no threat to the Christian who takes God at His word. Only further exploration of God's creation will reveal whether this "multiverse" is a true aspect of how God designed His creation to be, although the complete lack of compelling evidence for its existence makes this possibility seem highly unlikely.
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