It is now a reasonably well acknowledged facti that our Universe is “finely-tuned” for life. In other words, small differences in its fundamental laws and their numerical constants and initial conditions would mean that, not only “life as we know it”, but any form of physical life would be impossible. This is because the kinds of natural parameters and structures friendly to life (“biophilic”) are very particular. Long-term physical life requires concentrations of energy extracted from the surroundings combined with deep local drops in entropy, multiple and diverse interacting components operating as one integrated whole, and an environment which is sufficiently stable to permit time for growth or development but sufficiently “flexible” or non-constrained to allow non-repetitive, non-uniform arrangements of matter to exist. We need an interplay of stability with spatio-temporal complexity, of overarching order with potential for great variability. Complex instability or simple stability are easier to achieve and thus the natural expectations a priori. For example, small variations from the constants that determine our Universe’s properties would have meant nothing existed but a fairly uniform bath of radiation without matter or no elements except Hydrogen and Helium, or even a short-lived universe that only had time to “explode” and soon after collapse gravitationally.
Given that such “fine-tuning” is present, there are different inferences which can be made from this evidence. One is obviously the theist one which posits a supernatural and intelligent cause, God, who deliberately created Nature to be biophilic and, in particular, capable of producing &/or supporting intelligent life such as our own by “rigging” its laws and their constants. Then the suitability of the Universe for life is seen as due to the intention of God to create life and intelligence outside Himself, in the same way as the general and elegant mathematical ordering of the Universe is seen as due to the intention of God to create beauty and harmony outside Himself. The extraordinarily low probability of the biophilicity of Nature due to mere chance is also seen as evidence for the existence of such a God.
A second possible inference is that we are just extremely lucky and this biophilicity is a fluke, there being no need for a supernatural cause. However, given that calculations of the odds of biophilicity produce unimaginably small numbers, sometimes even when limiting consideration only to one “perfect” parameter at a time — numbers that are less than one in x, where x is much larger than the number of subatomic particles in the known universe (!) — atheists are becoming less inclined to pick this option. Instead, another two options are put forward, sometimes separately, sometimes together.
A third reaction notes that since we have not yet discovered the TOE (Theory of Everything), it may be that when we do so, the TOE actually sets the various constants or boundary conditions of nature at particular levels or within tightly constrained ranges. In this case, it is argued, the assumption that they could have taken on a much larger range of non-biophilic values is falsified and the previously calculated low probabilities become worthless. The problem with this is that even if it is true, it only moves the problem up one level, posing the question now as to why the TOE is so constructed that it automatically generates just the right numbers for life. Indeed, this whole escape route ignores the fact that it is the fundamental laws themselves that are already mysteriously biophilic, quite independently of the constants. Sometimes it is then argued that the TOE will be a mathematically “necessary” theory, as if a priori scientific or theoretical considerations can somehow rule out all or most other mathematically self-consistent alternatives. But this is clearly nonsense, since there are no mathematical reasons to exclude any self-consistent mathematical model, of which there are an infinite number, and there can be no empirical reasons either, since these are by definition a posteriori and thus irrelevant to any comparison with possible alternative universes. Given that on normal atheistic assumptions only mathematical and empirical propositions have any validity (following Hume and the later “logical positivists”), this leaves no room for justifying the “necessity” of a biophilic TOE.
The fourth possible inference, and a more apparently reasonable escape route from a theistic explanation, is to note that a number of plausible TOEs (albeit incomplete ones, as all are) are most naturally interpreted as predicting multiple universes, each varying somewhat from the others, and normally an infinite number. In the latter case the smallness of odds with regard to particular biophilic combinations of constants and boundary conditions is irrelevant, since no matter how unlikely these combinations, as long as they are not strictly impossible they are certain to occur and occur infinitely often. Given that, in such a situation, only biophilic universes (which are then inevitable) could possess rational living beings asking why their particular universe was biophilic, “observer selection” is said to answer their question: in other words, the reason our universe is biophilic is that it is a lucky exception to the norm made 100% probable by infinite “trials”, and we wouldn’t exist to ask the question unless we were in such a universe. The attentive reader will perhaps have noticed already that such a response to the evidence still does not deal with why the fundamental mathematical “shape” of the TOE allows for any biophilic universes within its ensemble and then makes them inevitable by intrinsically infinite fecundity. Neither quality is by any means a necessary consequence of every possible TOE. Although the number of theoretically possible mathematical equations that could describe a TOE is incalculably or indefinably infinite, as is the number within that set that would be biophilic, such that normal probability measures are useless, the extreme sensitivity of biophilicity to small (structural or numerical) variations from our actually operative TOE along with the requirements considered in the first paragraph above are sufficient to indicate that no scientific “multiverse” theory can make biophilicity a priori anything but highly improbable. In other words, one aspect of the “unlikelyhood” of biophilicity has been dealt with, but the most fundamental aspect has been ignored, leaving the evidence for design intact.vi
Unfortunately, not only have atheists incorrectly seen multiverse models as a way of undermining evidence for the biophilic design of Nature, but a number of Christians have agreed with them and reacted in a knee-jerk and dogmatically negative fashion to multiverse theories. So have some non-religious scientists and philosophers for various reasons. What I aim to do in this essay is to examine the objections and show that none of them shows multiverse theories are either irrational and unscientific or theologically “threatening” and inadmissable. However, this is far from showing they are true. As yet there is no clear empirical evidence for or against any multiverse theory.
I have so far ignored the most outlandish multiverse alternatives to the theistic explanation for fine tuning. I will deal with them briefly here.
One is the Everett “many-worlds” interpretation of Quantum Mechanics (QM), which relates closely to the “environmental decoherence” interpretation at its most persuasive. It “solves” the mystery of why the infinite and continuous set of possible solutions to QM wave equations governing matter collapse to discrete and particular actual observed events by claiming that every possible solution is in fact made actual in a distinct version of our Universe. This theory has a number of problems, including the fact that it would seem, contrary to claims commonly made on its behalf, it cannot explain without begging the question why we are never conscious of weird superpositions of what we know from experience to be mutually incompatible events. For example, there is nothing in its mathematics that prevents us from seeing the famous Schrodinger’s Cat as a mixture of the Dead and Alive state!
Another multiverse theory, that of Lee Smolin, posits that each black hole can create a new universe with somewhat different physical parameters from its source universe. Thus, since universes which encourage black hole formation will “reproduce” more, and do so with (limited) random variation in their laws and constants from generation to generation, a process analogous to biological evolution will ensure an infinite number of universes rather like ours will exist with every combination of physical parameters, and so biophilic universes become inevitable. However, this theory still needs an overarching TOE that is biophilic, and so does not really solve the problem. Also, there is no evidence that black holes can produce new universes at all, let alone of the right type, and entropy considerations would imply that anything they did produce would have very different and biophilically inferior initial configurations to our own universe.
Finally, there are the astonishing theories of Tegmark and Lewis, which can be placed in the category of “modal realism”. The former, a scientist, suggests that all possible mathematical structures for the TOE are instantiated in some universe or multiverse. The latter, a philosopher, goes broader still and says all possible universes exist, without requiring a mathematical underpinning. Such propositions are a “solution” to the fundamental problem of necessity and contingency: why does this “state of affairs” obtain and not another one just as possible on a priori principles? Their answer is that no answer to this question is possible, so the question must have a false assumption: that is, it falsely assumes all the other contingencies do not in fact exist in reality. By thus collapsing the contingent and the necessary into one infinite category where all that is possible, is, they have taken the opposite path to Leibniz, who solved the aforementioned problem by saying that this Universe must be the best of all possible Universes, so God “had” to choose to create this one if He created at all, in order to be consistent with His perfect nature. Ironically, such modal realists appeal to Occam’s Razor, the principle that the explanation that multiplies causal entities the most is the least likely to be true! They do this by arguing that, although their theories infer the existence of infinitely many unobservable Universes (or Multiverses), they rely on a singularly simple ontological premise, “all that could possibly exist does exist” and do not then need to complicate things by adding further premises or reasons which would limit reality to a very particular configuration with very particular properties and laws.** The problems with this scenario, apart from offending against common-sense, are as follows. First, it completely ignores the ontologically and logically prior problem of why anything exists at all rather than nothing. So, its appearance of explaining why things exist in particular ways is an illusion, as it explains the existence per se of nothing whatever, instead asking us to accept multifarious, complex existence as a brute fact and then taking the easy route to explain why existent entities have certain essences or natures: they are this way because it is possible to be this way, and every way it is possible to exist does in fact exist. Second, without a supervening and particular law of reality, there is no way of determining what is “possible” and what is not, so we still end up with some separate, singular and contingent TOE-like principle which requires explanation of both its existence and its “potency”, that is, the reason it necessitates the existence of other things. In other words, extreme modal realism doesn’t really solve the problem of contingency at all. Third, such ontological promiscuity includes an infinite number of universes almost exactly like our own except that their physical behaviour must diverge radically from ours at some point in time.** This could be due to a constant that obeys something like a weird and extreme (but mathematically possible) function, such as x = x0 + e1,000,000,000,000,000,000,000,000(t-t0), where x0 is the “normal” value and t0 is the time at which it “takes off” absurdly. Or, if non-mathematically consistent possibilities are allowed, it could be due to pixies with a weird sense of humour making the Universe appear to follow mathematical laws until they decide to pull the rug from under our comfortable scientific sensibilities. After all, what is logically impossible about the latter? However, what this means is that our appeal to inductive reasoning, which generalises laws from consistent observations over time and is essential to science, would be seemingly unjustifiable rationally, since we would have no reason to think we do not inhabit one of these many “crazy” universes. And yet, inductive scientific reasoning works. Therefore, I think we can safely ignore these kinds of multiverse theories too.
Instead, I am here addressing Multiverse theories that are genuinely plausible and based on a single, overarching mathematical TOE as yet to be determined, in order to show they are compatible with Christian theism. It is not my intent to describe or analyse their specific physics, but to look at their significance metaphysically and theologically…