Question: "What is the multiverse theory?"
Answer: In summary, the multiverse theory was invented to explain away the clear evidence of design in the universe along with the fact that the universe is finely-tuned to support life (the anthropic principle). The multiverse theory essentially states that there are multitudes of universes, each formed entirely randomly, with our universe being the only one (or one of a few) that randomly developed in such a way that it supports life. According to the multiverse theory, the appearance of “intelligent design” in our universe is the result of the pieces coming together just right, with no guidance/oversight from any Being. Rather, in this theory, our universe being fine-tuned for life is simply a matter of chance – with millions or billions of universes, it was bound to happen.
The multiverse theory is based on the supposition that what we have to this point considered to be “the universe” is but a small component of a vast, possibly infinite, assemblage of universes. The multiverse principle is an attempt to evade evidence for the apparent fine-tuning of cosmic laws, values and constants such that the universe would be conducive to bio-habitability. The core thesis of the multiverse concept attempts to expand one’s probabilistic resources beyond that which is available in the observable universe such that the likelihood of attaining a single bio-habitable universe by chance is rendered more plausible.
There are several fundamental problems with this proposition, the key problem being that it is both unnecessary and ad hoc. There is no good scientific reason to think that we reside in one universe within a multitude of parallel universes. There is also no reason to think that there should be a mechanism for generating such universes, each with its own fundamental constants and values. The proposition thus only succeeds in throwing the paradox back one step, as one could then easily ask who built the generator to give rise to this cosmic lottery. A second difficulty with this hypothesis is that a universe which is in a state of continuous expansion cannot be eternal. It stands to reason, therefore, that it is possible only a finite number of universes could have been generated, and there is no guarantee that a finely tuned bio-habitable universe would have emerged.
In conclusion, in the absence of independent philosophical and/or scientific evidence for the existence of a universe-ensemble, the concept remains nothing more than radical metaphysical conjecture. The exquisite fine-tuning of the contingent laws and constants of the universe for the emergence of complex life remains best explained by an intelligent Being outside of space and time. The popular worldview has, for decades, been that the universe did not have us in mind – that we exist as an infinite cosmic speck within a vast cosmic arena. In recent years, however, new insights have turned this paradigm on its head. Now we see evidence that life was planned, that it was intended (Psalm 19).