Tim Folger at Discover Online has a great piece on the choice confronting contemporary thinkers about what lies behind the universe's fine-tuning.
For those new to the discussion, fine-tuning refers to the fact that almost every fact about the universe has to be almost exactly what it is in order for the universe to be the kind of place in which higher life forms could thrive.
This means that hundreds of forces, parameters, values, etc. must be set to, in some cases, incredibly precise tolerances in order for the universe to exist at all and to be able to support life.
To take just one example, Hugh Ross invites us in Why the Universe Is the Way it Is to imagine that the universe were an aircraft carrier. If so, then had the mass at the beginning been off so much as the mass of a single fleck of paint, the universe would never have formed. Actually, Ross goes on to say, the tolerance is much less than that. In fact, if the mass of the universe were the same as the mass of an aircraft carrier it would only have to have been off by the mass of a billionth of a trillionth of the mass of an electron for the carrier to be unable to support living beings.
In the Discover article Folger interviews scientists who consider this amazing precision and conclude that there really are only two alternatives. Either the universe was intentionally designed or it's just one of a vast number of worlds which each possess different laws and forces. Amidst so much diversity the existence of a universe like ours, they aver, becomes much more probable:
Call it a fluke, a mystery, a miracle. Or call it the biggest problem in physics. Short of invoking a benevolent creator, many physicists see only one possible explanation: Our universe may be but one of perhaps infinitely many universes in an inconceivably vast multi�verse. Most of those universes are barren, but some, like ours, have conditions suitable for life.
The idea is controversial. Critics say it doesn't even qualify as a scientific theory because the existence of other universes cannot be proved or disproved. Advocates argue that, like it or not, the multiverse may well be the only viable non�religious explanation for what is often called the "fine-tuning problem"-the baffling observation that the laws of the universe seem custom-tailored to favor the emergence of life.
On the other hand, if there is no multiverse, where does that leave physicists? "If there is only one universe," says Bernard Carr, a cosmologist at Queen Mary University of London, "you might have to have a fine-tuner. If you don't want God, you'd better have a multiverse."
Precisely. In order to avoid having to admit that there's a God a lot of people are prepared to believe in a near infinite number of universes that they can neither see nor measure nor say much at all about. I daresay that were it not for the fact that the alternative was God, no scientist would be seriously entertaining a theory whose only purpose seems to be to serve as an escape hatch for atheistic materialists.
Folger's article does a fine job of explaining all the relevant ideas and will help you become conversant on an issue which we will no doubt be hearing much more about as science continues to discover more and more examples of the astonishing precision with which our world is engineered.
You might also want to pick up Hugh Ross' book which describes this precision in a fashion very accessible to those with a minimal background in science. It can be ordered by phone from my friend Byron at Hearts and Minds Bookstore.
RLC
