Bruce Gordon: problems with inflationary multiverse cosmologies

From Evolution News. Dr. Bruce Gordon reflects on whether the new BICEP2 results offer any support for the multiverse.

First, quick review of the Big Bang so we’re clear on the challenge that poses for naturalism:

Now, Big Bang theory has its theoretical basis in general relativity, which predicts that the universe is spatiotemporally expanding in the future direction and thus would be contracting if we were to reverse the direction of time. As Roger Penrose and Stephen Hawking showed in the late 1960s, no matter which general-relativistic model of our universe is chosen, this contraction leads to a beginning point in the finite past — a singularity, to use the technical term — from which not just matter and energy, but spacetime itself, emerged. This coming into existence of the universe from nothing (no space, no time, no matter, no energy, and hence no physical laws either) is what is known as the Big Bang. It is, as the agnostic astronomer Robert Jastrow once observed, startling evidence for the doctrine of creation ex nihilo. He famously put it this way:

For the scientist who has lived by his faith in the power of reason [editorial aside: Jastrow might better have said “faith in the sufficiency of materialist explanations” because the inference from the ex nihilo generation of the universe to a transcendent intelligent cause is eminently reasonable], the story ends like a bad dream. He has scaled the mountain of ignorance; he is about to conquer the highest peak; as he pulls himself over the final rock, he is greeted by a band of theologians who have been sitting there for centuries.

This having been established, as the physicist George Gamow demonstrated in 1948, one of the predictions of Big Bang theory is the existence of gravitational ripples and cosmic background radiation (CBR) that are an “echo of Creation,” as it were, throughout the whole observable universe. This cosmic background electromagnetic radiation was discovered in 1965 by Robert Wilson and Arno Penzias, a discovery for which they were awarded the Nobel Prize. In this regard, the alleged detection of gravitational waves would serve as further confirmation of the correctness of Einstein’s theory of general relativity and of the nature of the Big Bang itself. If corroborated by the scientific community, it would be a hugely important discovery, not just because of the evidence it provides for gravitational waves, but also because of the way this discovery is linked to another theory, namely, inflationary cosmology.

Inflationary cosmology is an enhancement to the standard Big Bang cosmology, and some models of inflationary theory can create additional universes. Some people are hoping that this will address the fine-tuning argument.

But Dr. Gordon is having none of that:

Of course, the inflationary mechanism is often regarded as generative of an unending and rapid succession of universes with the idea that, if enough universes are produced by such means, the improbabilities just mentioned don’t matter. Several things need to be said about this “inflationary multiverse” proposal:

(1) First of all, as pointed out by one of the physicists involved in the BICEP2 project, Kent Irwin at Stanford University, the BICEP2 results do not address the truth or falsity of inflationary multiverse theories.

(2) Secondly, attempting to swamp the improbabilities intrinsic to inflation by multiplying the number of universes it generates to the point of compensation has consequences that undermine scientific rationality. In a materialist multiverse resting on the hypothesis of an undirected and irreducibly probabilistic quantum inflationary mechanism that lacks any principle of sufficient material causality, anything can happen for no reason at all. What is more, quantum-mechanically speaking, everything that can happen, no matter how improbable, does happen, and it happens with unlimited frequency. In this environment we can have no confidence that the future will resemble the past in a way that legitimates uniformitarian assumptions and the very inductive inferences that make science possible. In short, taken seriously, the inflationary multiverse proposal completely undermines scientific rationality.

(3) Thirdly, at least two paradoxes result from the inflationary multiverse proposal that suggest our place in such a multiverse must be very special: the “Boltzmann Brain Paradox” and the “Youngness Paradox.” In brief, if the inflationary mechanism is autonomously operative in a way that generates a multiverse, then with probability indistinguishable from one (i.e., virtual necessity) the typical observer in such a multiverse is an evanescent thermal fluctuation with memories of a past that never existed (a Boltzmann brain) rather than an observer of the sort we take ourselves to be. Alternatively, by a second measure, post-inflationary universes should overwhelmingly have just been formed, which means that our existence in an old universe like our own has a probability that is effectively zero (i.e., it’s nigh impossible). So if our universe existed as part of such a multiverse, it would not be at all typical, but rather infinitely improbable (fine-tuned) with respect to its age and compatibility with stable life-forms.

(4) Fourthly, a mechanism that generates universes ad infinitum must have stable characteristics that constrain its operation if it is to avoid breaking down and sputtering to a halt. In short, universe-generators have finely tuned design parameters that themselves require explanation. So postulating a universe-generator to explain away the appearance of first-order design in a single universe does not obviate the inference to design, it merely bumps it up to the next level. Avoiding an infinite regress of explanatory demands leads to the recognition of actual design terminating in an Intelligence that transcends spacetime, matter and energy, and which, existing timelessly logically prior to creating any universe or multiverse, must also therefore exist necessarily, and therefore require no further explanation of its own existence.

(5) Fifthly and finally, as demonstrated by Arvind Borde, Alan Guth, and Alexander Vilenkin in 2003 (see further reading suggestions below), any inflationary multiverse has a beginning in the finite past: while inflationary models can, in theory, be eternal into the future, it is mathematically impossible for them to be eternal into the past. This means that the inflationary multiverse entails creation ex nihilo in precisely the same manner as the Big Bang. The universe thus manifests dependence on a transcendent reality in respect of its origin, but what is more, in virtue of the manifest absence of sufficient material causation in many aspects of its persistence as a quantum-mechanical phenomenon, the material universe also manifests dependence on a transcendent reality in respect of its operation (for an extended argument to this effect, see my article on quantum-theoretic challenges to philosophical naturalism referenced in the suggested readings).

What all of this reveals, of course, is that it’s intelligent design all the way through and all the way down and that theophobic scientific materialists, once they get past knee-jerk denials, must come to terms with what is, for them, a worldview-defeating fact.

The Boltzmann Brain paradox in point 3) came up as a problem with inflationary multiverse cosmologies in the recent Craig-Carroll debate.

I bolded part 4) because as Dr. Robin Collins has argued before, the multiverse-generation mechanism does not get rid of the fine-tuning, it just pushes it up one level. And I bolded part 5) because Dr. Gordon is alluding to the Borde-Guth-Vilenkin (BGV) theorem there, which always comes up in debates on cosmology. The theory applies to inflationary cosmologies: they still require an absolute beginning. These are serious problems that we should not gloss over when people push a speculative model like the multiverse in order to escape the fine-tuning argument.

I always thought of Dr. Gordon as kind of a moderate Canadian guy, but I love that last line, don’t you? :) Don’t fear the reaper, naturalists.

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