(…) Physicists don’t like coincidences. They like even less the notion that life is somehow central to the universe, and yet recent discoveries are forcing them to confront that very idea. Life, it seems, is not an incidental component of the universe, burped up out of a random chemical brew on a lonely planet to endure for a few fleeting ticks of the cosmic clock. In some strange sense, it appears that we are not adapted to the universe; the universe is adapted to us.
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 multiverse. 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 nonreligious 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.
“I don’t think that the multiverse idea destroys the possibility of an intelligent, benevolent creator,” Weinberg says. “What it does is remove one of the arguments for it, just as Darwin’s theory of evolution made it unnecessary to appeal to a benevolent designer to understand how life developed with such remarkable abilities to survive and breed.”
On the other hand, if there is no multiverse, where does that leave physicists? “If there is only one universe,” Carr says, “you might have to have a fine-tuner. If you don’t want God, you’d better have a multiverse.”
As for Linde, he is especially interested in the mystery of consciousness and has speculated that consciousness may be a fundamental component of the universe, much like space and time. He wonders whether the physical universe, its laws, and conscious observers might form an integrated whole. A complete description of reality, he says, could require all three of those components, which he posits emerged simultaneously. “Without someone observing the universe,” he says, “the universe is actually dead.” (…)