Science's Alternative to an Intelligent Creator: the Multiverse Theory
Our universe is perfectly tailored for life. That may be the work of God or the result of our universe being one of many.
by Tim Folger
A sublime cosmic mystery unfolds on a mild summer afternoon in Palo Alto, California, where I’ve come to talk with the visionary physicist Andrei Linde. The day seems ordinary enough. Cyclists maneuver through traffic, and orange poppies bloom on dry brown hills near Linde’s office on the Stanford University campus. But everything here, right down to the photons lighting the scene after an eight-minute jaunt from the sun, bears witness to an extraordinary fact about the universe: Its basic properties are uncannily suited for life. Tweak the laws of physics in just about any way and—in this universe, anyway—life as we know it would not exist.
Consider just two possible changes. Atoms consist of protons, neutrons, and electrons. If those protons were just 0.2 percent more massive than they actually are, they would be unstable and would decay into simpler particles. Atoms wouldn’t exist; neither would we. If gravity were slightly more powerful, the consequences would be nearly as grave. A beefed-up gravitational force would compress stars more tightly, making them smaller, hotter, and denser. Rather than surviving for billions of years, stars would burn through their fuel in a few million years, sputtering out long before life had a chance to evolve. There are many such examples of the universe’s life-friendly properties—so many, in fact, that physicists can’t dismiss them all as mere accidents.
“We have a lot of really, really strange coincidences, and all of these coincidences are such that they make life possible,” Linde says.
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.
Physical laws clamor for life: the universe knew we were coming.“For me the reality of many universes is a logical possibility,” Linde says.
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“If you allow yourself to hypothesize an almost unlimited portfolio of different worlds, you can explain anything,” says John Polkinghorne, formerly a theoretical particle physicist at Cambridge University and, for the past 26 years, an ordained Anglican priest. If a theory allows anything to be possible, it explains nothing; a theory of anything is not the same as a theory of everything, he adds.
If the Planck satellite detects bending light, that would be evidence for the multiverse.Supporters of the multiverse theory say that critics are on the wrong side of history. “Throughout the history of science, the universe has always gotten bigger,” Carr says. “We’ve gone from geocentric to heliocentric to galactocentric. Then in the 1920s there was this huge shift when we realized that our galaxy wasn’t the universe. I just see this as one more step in the progression. Every time this expansion has occurred, the more conservative scientists have said, ‘This isn’t science.’ This is just the same process repeating itself.”
If the multiverse is the final stage of the Copernican revolution, with our universe but a speck in an infinite megacosmos, where does humanity fit in? If the life-friendly fine-tuning of our universe is just a chance occurrence, something that inevitably arises in an endless array of universes, is there any need for a fine-tuner—for a god?
“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.”
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