From the Guardian's Cif Belief...

Is there a God or a multiverse? Does modern cosmology force us to choose? Is it the case that the apparent fine-tuning of constants and forces to make the universe just right for life means there is either a need for a "tuner" or else a cosmos in which every possible variation of these constants and forces exists somewhere?

This choice has provoked anxious comment in the pages of this week's New Scientist. It follows an article in Discover magazine, in which science writer Tim Folger quoted cosmologist Bernard Carr: "If you don't want God, you'd better have a multiverse."

Even strongly atheistic physicists seem to believe the choice is unavoidable. Steven Weinberg, the closest physics comes to a Richard Dawkins, told the eminent biologist: "If you discovered a really impressive fine-tuning ... I think you'd really be left with only two explanations: a benevolent designer or a multiverse."

The anxiety in the New Scientist stems in part from the way this apparent choice has been leapt upon by the intelligent design people. Scientists don't like that since it seems to suggest that ID offers a theory that cosmologists are taking seriously. It doesn't of course: ID wasn't science before the multiverse hypothesis gained prominence, just a few years ago; and it hasn't become science since.

Further, if you bow to ID, the implication is that science should brush certain ideas under the carpet just because its ideological opponents find false succour in them. Physics has already learnt not to do that: some cosmologists ignored the hypothesis of a big bang for a while, believing it lent credence to the account of creation in the Bible. The big bang, though, turned out to be hugely more likely than the steady state theory that preceded it. The correct stance is to recognise that reading creation myths as scientific theory is just a category mistake.

Which is precisely why the choice between God or a multiverse is false too. If divinity is an explanation for anything, it is not a scientific explanation. A scientific explanation is precisely that, an explanation from within the laws of science. God, for believers, is the condition without which science cannot even get going; divinity is a final explanation for the laws of science, as a philosopher of religion would say.

To confuse the two is the fundamental theological mistake made by ID. It is also why you could have God and a multiverse without creating any significant theological problems. Believers don't have to choose. They can have both if they want.

That said, there are other, powerful reasons for rejecting a multiverse. Finding conclusive evidence in support of the hypothesis seems highly unlikely; even its advocates admit as much. Worse, it is not clear a multiverse explains anything anyway ??" stating instead that everything is possible somewhere. If science routinely proceeded on that basis, it would have to conclude that God exists in some universes, following Richard Dawkins' reasoning that whilst God is highly unlikely, the possibility cannot be ruled out tout à fait. (That said, Dawkins' argument is itself flawed, because if God existed the deity would be a necessary not contingent being, and so not subject to the laws of probability.)

In the New Scientist, appeal is made to another alternative, so-called "top-down" cosmology. The idea here is that observation is needed to bring the universe into full being. It borrows from one interpretation of quantum mechanics, in which observation is needed to decide whether a particle is in one state or another ??" the paradox famously caught in the thought experiment of Schrödinger's Cat. The originator of these kind of hypotheses, the theoretical physicist John Wheeler, put it this way: "(The cosmos) has not really happened, it is not a phenomenon, until it has been observed to happen."

As you might suspect, such cosmologies are themselves highly speculative, to say the least. For one thing, physicists are far from settled on just how to interpret quantum mechanics, which is to say that observation may yet prove to play no part in it. Also, it is unclear just what is meant by observation in this context.

Roughly, though, one idea would be that "observers" are creating the universe, or to put it another way, the universe emerges with observation. In the early stages of the universe, before human observers, it might be that the interactions of subatomic particles would function as observations, since they in some weak sense "recognise" one another in their interactions. Over the aeons, conscious observers finally emerge. In the future, perhaps some even more subtle notion of observation will come about and human consciousness itself will come to be seen as but part of the story.

Time will tell, or not. What is fascinating now, though, is that these new cosmologies arguably introduce into physics phenomena like mind, purpose and intentionality, since that is what human observation is. In other words, if the choice between God or a multiverse is misconceived, it also masks a far more interesting possibility, namely a radical change in what is understood by physics: top-down cosmologies would introduce metaphysics into the equation, in particular teleological notions.

The possibility that the universe has directionality or purpose, even if self-contained ??" that is, not making any appeal to an external deity ??" has been forcefully rejected by most of modern science. But maybe the extraordinary phenomenon that is an evolving universe containing conscious observers is itself forcing science to reconsider.