Robin Collins, professor of philosophy at Messiah College (who also holds a PhD. in physics [double PhD. types really make me feel inferior]) has written an interesting response to the Multiverse scenario in his paper God, Design, and Fine-Tuning:
One major theistic response to the many-universes generator scenario, whether of the inflationary variety or some other type, is that a “many-universes generator” would seem to need to be “well-designed” in order to produce life-sustaining universes. After all, even a mundane item like a bread machine, which only produces loaves of bread instead of universes, must be well designed to produce decent loaves of bread. If this is right, then invoking some sort of many-universes generator as an explanation of the fine-tuning only kicks the issue of design up one level, to the question of who designed the many-universes generator.
The inflationary scenario discussed above is a good test case of this line of reasoning. The inflationary/superstring many-universes generator can only produce life-sustaining universes because it has the following “components” or “mechanisms:”
i) A mechanism to supply the energy needed for the bubble universes: This mechanism is the hypothesized inflaton field. By imparting a constant energy density to empty space, as space expands the inflaton field can act “as a reservoir of unlimited energy” for the bubbles (Peacock, 1999, p. 26).
ii) A mechanism to form the bubbles: This mechanism is Einstein’s equation of general relativity. Because of its peculiar form, Einstein’s equation dictates that space expand at an enormous rate in the presence of a field, such as the inflaton field, that imparts a constant (and homogenous) energy density to empty space. This causes both the bubble universes to form and the rapid expansion of the pre-space (the “ocean”) which keeps the bubbles from colliding.
iii) A mechanism to convert the energy of the inflaton field to the normal mass-energy we find in our universe. This mechanism is Einstein’s relation of the equivalence of mass and energy (i.e., E = mc2 ) combined with an hypothesized coupling between the inflaton field and normal mass-energy fields we find in our universe.
iv) A mechanism that allows enough variation in the constants of physics among universes: The most physically viable candidate for this mechanism is superstring theory. As explained above, superstring theory might allow enough variation in the variations in the constants of physics among bubble universes to make it reasonably likely that a fine-tuned universe would be produced. The other leading alternatives to string theory being explored by physicists, such as the currently proposed models for Grand Unified Field Theories (GUTS), do not appear to allow for enough variation.
Without all these “components,” the many-universes generator would almost certainly fail to produce a single life-sustaining universe. For example, Einstein’s equation and the inflaton field harmoniously work together to enormously inflate small regions of space while at the same time both imparting to them the positive energy density necessary for a universe with significant mass-energy and causing the pre-space to expand rapidly enough to keep the bubble universes from colliding. Without either factor, there would neither be regions of space that inflate nor would those regions have the mass-energy necessary for a universe to exist. If, for example, the universe obeyed Newton’s theory of gravity instead of Einstein’s, the vacuum energy of the inflaton field would at best simply create a gravitational attraction causing space to contract, not to expand. Thus no universes would be formed.
[By the way, I make no claim to understanding most of this. But there are at least a few of you out there who do. And I forgot to add this part:]
In addition to the four factors listed above, the inflationary/superstring many-universes generator can only produce life-sustaining universes because the right background laws are in place. For example, as mentioned earlier, without the principle of quantization, all electrons would be sucked into the atomic nuclei and hence atoms would be impossible; without the Pauli-exclusion principle, electrons would occupy the lowest atomic orbit and hence complex and varied atoms would be impossible; without a universally attractive force between all masses, such as gravity, matter would not be able to form sufficiently large material bodies (such as planets) for life to develop or for long-lived stable energy sources such as stars to exist.
In sum, even if an inflationary/superstring many-universes generator exists, it along with the background laws and principles could be said to be an irreducibly complex system, to borrow a phrase from biochemist Michael Behe (1996), with just the right combination of laws and fields for the production of life-permitting universes: if one of the components were missing or different, such as Einstein’s equation or the Pauli-exclusion principle, it is unlikely that any life-permitting universes could be produced. In the absence of alternative explanations, the existence of such an a system suggests design since it seems very unlikely that such a system would have just the right components by chance. It does not seem, therefore, that one can escape the conclusion of design merely by hypothesizing some sort of many-universes generator.