Introduction
As a Christian who is deeply interested in the sciences and what they bring to the table for defending the existence of God (and the truth of the Christian worldview, specifically), I have often encountered the idea that multiple worlds may exist, which seems to explain away the beginning of the universe and its designed features. When I heard that astrophysicist Jeff Zweerink (Apologetics 315 Interview) wrote an introduction booklet addressing that very challenge, it caught my attention. "Who's Afraid of the Multiverse?" (paperback, Kindle, Video) provides an introduction to the concept of the multiverse and what its implication is for arguments for God's existence. It is a short read at only 53 pages.The Multiverse Landscape
Zweerink spends the first half of the book setting the stage for why discussions of a "multiverse" are even necessary and explaining what scientists mean by the term. Various observations of the universe have led scientists to believe that the universe experienced a period of expansion speeds exceeding the speed of light. Though the evidence is strong that this took place, exactly how and what caused it to begin and end are currently under investigation. One of the types of multiverse is a necessary implication of the fact of inflation, and one of the other types is a necessary implication of a particular model for the possible mechanism of inflation. Each progressive type becomes more speculative and enjoys less scientific evidence than the previous one.The term "multiverse" has four different meanings. The first (Type 1 multiverse) is more of a misnomer because it merely refers to the area of our universe outside what we currently observe. If inflation did take place in the early moments of our universe (as observations powerfully suggest), then there exists regions in our universe that the light has not had time to travel to our telescopes yet. The regions outside the viewing area of any observer at any point in the universe are referred to as a different observable universe. Since multiples exist, the term multiverse is applied to the entire universe which contains these many observable universes.
The second (Type 2) results from a model for the mechanism that ends the inflation of our universe. This particular model is a type of inflation that operates outside our universe (in its own "space") and generates numerous Type 1 multiverses (universes). Each of these may contain different or the same laws of physics. With different laws, this potentially provides this type of multiverse the explanatory power to naturalistically accommodate the fine-tuning of the laws of physics of our universe. And with the same laws (universes that may still not ever result in life or advanced life), this multiverse potentially naturalistically explains the fine-tuning of conditions within the confines of the laws of physics to produce life (and advanced life).
The third (Type 3) is based on an interpretation of quantum mechanics. The idea is that every event (whether a decision from a free agent or a natural event- any in which another could have taken place) results in the creation of new timelines that each contain one alternative event. All counterfactuals are actually real ("counterfactual" is actually a relative term to the timeline of the viewer) and those realities are their own unique universes that will never interact with each other ever again. Because of the orders of magnitude of universes created in this theory, this is also called a multiverse. Because of the many possible interpretations of quantum mechanics, the reality of this particular type of multiverse is dependent upon which interpretation of quantum mechanics is found to be true (or which ones are removed as they are tested against reality).
The fourth (Type 4) is the most speculative of all and does not enjoy any scientific evidence supporting its existence. This type of multiverse simply posits that all mathematically possible universes exist. If it is true, then it effectively eliminates the distinctions among the other three multiverse types because they all result in universes that are mathematically possible. But since the others would not necessarily produce all mathematically possible universes, this type would contain the largest number of universes and potentially contain all the explanatory power of the previous ones combined.
Apologetic Impact of the Multiverse
Theists often use the cosmological argument and the teleological argument for God's existence. Naturalists have been hopeful that the multiverse would be able to undermine the power of these arguments by eliminating the beginning of the universe and explaining the apparent design by greatly multiplying the number of universes with different laws of physics. Zweerink demonstrates, though, how neither of these arguments is in any danger by the existence of a multiverse. He even shows how both arguments would actually be made more robust should a multiverse actually exist.Scientific Objections to the Multiverse
Be that as it may, many objections to the multiverse do exist, so the Christian should not be too excited to embrace it yet. Zweerink describes three scientific evidences that currently stand against predictions made by multiverse models. But scientific observations are not the only issues that plague the multiverse.Philosophical Difficulties
Discussing strictly naturalistic multiverse models, Zweerink shifts from the scientific to the philosophical to demonstrate more challenges. He addresses the absurdity of infinities, the crisis of identity, and the problem of justice and free will. The first issue applies only to the multiverse, but the other issues apply to any naturalistic scenario; the multiverse would just make those arguments against naturalism more powerful.Natural or Designed?
Regardless of whether or not a multiverse actually exists, Zweerink explains that the important focus for the Christian in discussions is the explanatory power of the multiverse when presented as an alternative to God. He explains five necessary criteria that a naturalistic multiverse fails to meet. He also puts forth a biblical case for the existence of realms beyond the one we experience. Not only does a multiverse not remove God from the equation (and, in fact, still requires Him), but it is not necessarily incompatible with the Christian worldview.What To Do With the Multiverse
Zweerink concludes the booklet by recommending that the Christian who's confronted with the multiverse as an alternative explanation to God to focus on the scientific and philosophical evidence that does exist, rather than entertain speculations. He reminds the reader that the focus in any discussion of this sort should be centered on the Gospel and that using the evidence presented here will help remove any kind of multiverse as a stumbling block to Jesus Christ.Reviewer's Thoughts
In recent years the idea of a multitude of universes has become a favorite "Plan B" of naturalists who wish to escape the conclusions of arguments for God's existence, but cannot. Zweerink has put together a handy booklet that will give the reader a quick overview of the models that they may encounter. For the most part, the content was easy to digest, but familiarity with the cosmological, teleological, and other philosophical arguments for God's existence is handy to help connect the dots. Zweerink did not intend to provide a comprehensive explanation or critique of every topic discussed, but he heavily noted his discussions with deeper resources for those who wish to research further.A good amount of previous apologetic knowledge is extremely helpful to the reader, and a lack of it may leave the reader confused in several areas. While I would not recommend this book for a Christian who has not been exposed to the arguments for God's existence, I highly recommend it for any Christian who interacts apologetically with scientifically minded skeptics on a regular basis, but is not familiar with or is confused by the mess of information about multiverse models available. For the informed reader, Zweerink describes important distinctions and subtleties that will help them nuance their response to the multiverse challenge.
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Thanks to Brian Auten at Apologetics 315 for originally publishing this review on his site. This review is only one of many in a project by Auten to build a solid collection of reviews of books of interest to Christian apologists. His collection grows on a weekly basis