God and the multiverse

Jerry Coyne stumbled on the following, from Paul Davies:

Q: Do you think one reason the multiverse theory has become so popular in recent years is to keep the whole idea of God at bay?

A [Davies]: Yes.

Then later

“There’s no doubt that the popularity of the multiverse is due to the fact that it superficially gives a ready explanation for why the universe is bio-friendly. Twenty years ago, people didn’t want to talk about this fine-tuning because they were embarrassed. It looked like the hand of a creator. Then along came the possibility of a multiverse, and suddenly they’re happy to talk about it because it looks like there’s a ready explanation. . . Even the scientific explanations for the universe are rooted in a particular type of theological thinking. They’re trying to explain the world by appealing to something outside of it.”

In case you don’t have your scorecard handy, Coyne is a scientist with a very strong skeptical stance. Davies is a physicist who is Christian and generally “accommodationist” — that is, he tends to argue in favor of the compatibility of science and religion. [Update: Apparently I was wrong to describe Davies as Christian — see comments below. My apologies for the error.]

Coyne rightly detects the scent of bullshit here. Physicists these days talk quite a bit about theories involving multiple universes, for reasons that come out of various scientific arguments, not for anti-religious reasons at all. If you want to know more, and you’re going to be a first-year student at UR next year, take my first-year seminar, Space is Big. If you’re not, you could do a lot worse than to read Brian Greene’s book on the subject.

Coyne quotes Sean Carroll extensively to explain why Davies is wrong. From Coyne’s blog post:

The multiverse idea isn’t a “theory” at all; it’s a prediction made by other theories, which became popular for other reasons. The modern cosmological version of the multiverse theory took off in the 1980′s, when physicists took seriously the fact that inflationary cosmology (invented to help explain the flatness and smoothness of the early universe, nothing to do with God) often leads to the creation of a multiverse (see here for a summary). It gained in popularity starting around the year 2000, when string theorists realized that their theory naturally predicts a very large number of possible vacuum states (see e.g. http://arxiv.org/abs/hep-th/0302219). All along, cosmologists have been trying to take the predictions of their models seriously, like good scientists, not trying to keep God at bay.

This is all exactly right. But one thing Carroll and Coyne don’t point out is that Davies is wrong in his premise, not just his conclusion. To be specific, this is quite simply factually false:

Twenty years ago, people didn’t want to talk about this fine-tuning because they were embarrassed.

I happen to have been hanging around one of the leading cosmology groups in the world at that time (as a graduate student at UC Berkeley), and I can tell you that everyone talked about fine-tuning all the time.

At that time, multiverse-based explanations were not popular, and the various fine-tuning problems (i.e., why conditions in the Universe seemed to be surprisingly well-adapted for life) were regarded as mysterious and as-yet unsolved problems. Davies would have you believe that we didn’t want to talk about those problems because we didn’t have good (non-religious) answers to them. On the contrary, because we didn’t have answers to them, we talked about them incessantly. That’s what scientists do: there’s nothing we like more than a meaty unsolved problem! The idea that we were afraid of this sort of problem because it might force us into dangerous religious territory is the precise opposite of the truth.