It’s no surprise that the universe is habitable

It’s not unusual to hear the argument from incredulity (‘here’s something that’s really weird, therefore god exists’), but it is rare that you hear it coming from a Professor of Philosophy. But that’s exactly what Prof Robin Collins, at the evangelical Messiah College in Pennsylvania, is doing over at Science and Religion Today (and on the PBS series Closer to Truth: Cosmos, Consciousness, God).

His basic idea is that the universe is finely tuned to be hospitable for life. Since we don’t have a particularly good explanation yet for exactly why the universe turned out the way it did, this counts as evidence for the existence of god!

Here’s an excerpt:

I believe we can say that the fine-tuning of the universe provides significant evidence in support of divine creation over this hypothesis. The reason for this can be articulated in terms of what is often called the “likelihood principle,” but which I call the “surprise principle.” Roughly, this principle states that whenever a body of evidence is much more surprising under one hypothesis than another, it counts as evidence in favor of the hypothesis under which it is least surprising.

… it could be argued, given the fine-tuning, that the existence of a life-permitting universe is very surprising under the brute fact hypothesis, but not under theism. Therefore, by the surprise principle, fine-tuning provides significant evidence in favor of theism over the brute fact hypothesis. Nonetheless, it does not prove theism is true, or even show it is the best explanation of the universe. So faith—understood as a special mode of knowing similar to our ethical intuitions—still plays an essential role in belief in God, but the fine-tuning offers significant confirming evidence for this belief. In any case, the fine-tuning evidence offers a significant challenge to those who claim that the findings of science undercut belief in God.

Well I have some news for Prof Collins. It isn’t a surprise that the universe we live in is suitable for people to live in – in fact it’s bleeding obvious! If the universe was not habitable, then we wouldn’t be able to live in it, and we wouldn’t be able to sit around pontificating on its origin.

This, of course, is the ‘anthropic principle’, and as explanations go it’s almost – but not quite – as unsatisfactory as the ‘god hypothesis’. But it’s perfectly plausible and, no matter how many potential universes there are out there, it’s entirely unsurprising that the one we’re is, like the little bear’s porridge, just right.

But here’s another flaw in Prof Collins’ argument. It’s an argument from ignorance – otherwise known as the ‘god of the gaps’ approach. It presumes that our current understanding is complete and entire, and that anything we don’t understand counts as evidence for the existence of god.

In fact, Fred Adams of the University of Michigan in Ann Arbor has recently shown that all this talk of the universe being fine-tuned is based on a false, simplistic premise. Here’s how the New Scientist reported it:

Claims of fine-tuning have generally been based on what happens when you vary a single characteristic of the universe, say the strength of gravity, while holding all others constant. That, says Adams, is too artificial a scenario to tell you anything about whether there are other universes that can support life. “The right way to do the problem is to start from scratch,” he says. “You have to turn all the knobs and find out what happens.”

Adams selected a range of possible values for each of these constants, then put them into a computer model that created a multitude of universes, or a virtual “multiverse”. Each universe within the multiverse used different values for the three constants and was subject to slightly different laws of physics.

About a quarter of the resulting universes turned out to be populated by energy-generating stars. “You can change alpha or the gravitational constant by a factor of 100 and stars still form,” Adams says, suggesting that stars can exist in universes in which at least some fundamental constants are wildly different than in our universe.

And though some universes were filled with things we might not usually think of as stars – radiating black holes or bodies formed of dark matter – they all gave out enough energy to power some form of life, and lasted long enough for life to evolve.

Adams reckons his results, which will be published in the Journal of Cosmology and Astroparticle Physics, suggest that the “specialness” of our universe could well be an illusion. And this is only the very beginning of what can be probed to undermine the idea that our universe is fine-tuned for life. There are plenty more constants and processes that can be tinkered with, he says.

Adams’s approach is “extremely interesting”, says Michael Murphy of Swinburne University of Technology in Melbourne, Australia. “I’ve long had a suspicion that this talk of fine-tuning needs constant questioning and re-examination,” he says. “It’s sometimes hard to recognise that living somewhere else in a different way might be just as easy.”

And Adams isn’t the only one working along these lines. Stephen Hawking and Thomas Hertog (of Denis Diderot University, Paris) have recently proposed an interpretation of string theory that cuts down the apparent improbability of our ‘inflationary’ universe by recognizing that the probability estimate needs to be weighted by volume of the universe.

Now, of course the god theory doesn’t actually predict that the universe is improbable – because the god theory doesn’t actually predict anything at all. So proving that the universe isn’t improbable won’t count as evidence against the existence of god – at least the religious won’t be persuaded. But at least it will reduce the numbers of specious ‘god of the gaps’ arguments by one!