George Johnson in The New York Times reviews a book by physicist Leonard Susskind who is a strong advocate of the idea that there are a near infinite number of mini-universes in our universe, like bubbles in a bubble bath. According to Johnson this theory is appealing. Here's what he says:
Three years ago in "The Cosmic Landscape: String Theory and the Illusion of Intelligent Design," Leonard Susskind, a professor of theoretical physics at Stanford, spun a tale of a multitude of different universes - nooks and crannies of a transcendent multiverse, or "landscape," each ruled by a different physics. This is probably the most controversial interpretation of superstring theory (some of Susskind's colleagues absolutely hate the idea), but it has its appeal. With so many universes out there, the fact of our own existence need not inspire worship and awe. We just happen to occupy one of the niches where the laws are favorable to carbon-based life.
Notice in what the attraction of this theory consists for Johnson. It's not that it is empirically verifiable or that it explains the data or that it is aesthetically elegant. No. For Johnson and others the appeal of the multiverse is that it allows us an out, an escape, from the conclusion that our world is so incredibly organized that it all but screams for an explanation grounded in an intelligent engineer.
According to Johnson, if a world representing every possible physics exists then a world with our physics must exist, and we shouldn't be astonished by its extraordinary fine-tuning and precision. Nor need we conclude that an intelligent designer created it. Johnson is doing metaphysics and calling it science. The multiverse is appealing not because the science confirms it but because it allows us to side-step the conclusion that there's a God.
Susskind himself once said that the only two alternatives are an infinite number of universes or a designer deity. The idea of a deity is presumably philosophically unpalatable so he opts for the multiverse, and Johnson, who also finds a deity philosophically unacceptable, follows along.
But this idea that we are justified as scientists in embracing the theory of the multiverse because it's metaphysically useful raises a host of questions: Why would a scientist, qua scientist, want to avoid the conclusion that there's something more to the universe, an intelligence, that science has been unable to discern so far? Why should a scientist, qua scientist, be invested in the answer to the question of what is ultimately real anyway? Isn't that outside the scientific purview? Shouldn't questions about the cause and structure of the universe be settled, for scientists, at least, on empirical grounds rather than metaphysical flights of fancy?
Philosopher and psychologist William James once wrote that any rule of thought that would prevent me from finding a truth, were that truth really there, is an irrational rule. The rule of thought that says that any explanation of ultimate reality must be a naturalistic explanation - which is the rule embraced by many scientists - would prevent us from concluding that God is really the ground of creation even if God really is that ground. According to James, then, it's irrational to accept the multiverse simply because it's the only alternative to transgressing the bias among many scientists against explanations which invoke intelligent causation.RLC