J. Warner Wallace, in his new book God’s Crime Scene: A Cold-Case Detective Examines the Evidence for a Divinely Created Universe, investigates the causes of the fine tuning of our universe. One of the most popular explanations is that there exists multiple universes (the multiverse) and ours is just lucky enough to have the fine tuning that permits life.
Wallace presents the multiverse theory as an explanation for fine tuning as follows:
Multiverse explanations, however, point once again to an external causal agent: a mechanism capable of creating an incredibly large number of universes, each with its own set of physical laws. Most of these universes in the multiverse collection are incapable of permitting life. Our universe, however, through “a series of cosmic accidents,” just happens to support our existence.
Multiverse theories overcome the incredible odds against life (and explain the appearance of fine-tuning) by increasing the chances of such a life-permitting universe. Multiverse theorists have proposed the creation of multiverses through a number of mechanisms, most commonly by way of “eternal inflation,” or “quantum tunneling.” Some physicists suggest the existence of an eternal, primordial vacuum (as we discussed in the last chapter).
According to proponents of eternal inflation models, if an infinitely old vacuum has been experiencing inflation, and the tiny bubble universes we described have emerged, each bubble universe might have its own characteristics and physical laws. Other physicists (such as Alex Vilenkin) propose “quantum tunneling from nothing” to explain the existence of an ensemble of universes without eternal inflation. In these quantum tunneling models, diverse universes pop into existence, because in “quantum mechanics the behavior of physical objects is inherently unpredictable and some quantum processes have no cause at all.”
In both eternal inflation and quantum tunneling models, the universes (some older than others) emerging from the vacuum coexist within the larger multiverse. In each of these proposals (eternal inflation, quantum tunneling, and even string theory models), the existence of a vast array of universes makes one like ours an inevitability.
Given a vast array of universes, one of them was bound to support life, goes the argument. The different forms of the multiverse theory each attempt to describe the mechanism for the creation of all these universes, but the outcome is the same: a massive number of universes.
But do these multiverse theories truly explain the fine tuning of our universe? Wallace thinks not. First, he argues that the multiverse theory lacks evidential confirmation.
Like string theory or M-theory proposals, multiverse models lack observational or experimental evidence. Scientists can’t access other universes in the multiverse because they are separated within the vacuum by too great a distance (and according to these theories, this distance is growing). As a result, many scientists, especially string theorists, are suspicious about the existence of a multiverse. Some call it a “fantasy”; others call it “intellectually bankrupt” or a “cheap way out.” Lacking evidential support, many physicists see the multiverse theory as deficient when compared to efforts to find unity within the laws of physics.
But eternal inflation models face an even greater barrier. Our expert witness Alexander Vilenkin has already testified (along with Arvind Borde, Alan Guth, and Audrey Mithani) against the possibility of an eternal, uncaused, expanding vacuum. According to these experts, if inflation (expansion) has been occurring in this vacuum, it must have had a beginning and therefore cannot be eternal.
In part 2, we will look at 3 more reasons multiverse theories fail to adequately explain the origins of fine tuning.