Pick a universe, any universe. How many hypothetical universes would support life?
Possibly only one, say the authors of a new study. Published in the July issue of Science, the report says that if the physical forces within stars were only slightly different, our universe would be almost devoid of carbon and oxygen, and life would not exist.
The findings bring scientists face to face with the question of design. "I am not a religious person, but I could say this universe is designed very well for the existence of life," said Heinz Oberhummer, astrophysicist at the University of Vienna, Austria.
Mr. Oberhummer and his colleagues used computers to simulate the process by which helium burns to produce carbon and oxygen during the red-giant stage of a star's life. They found that even slight changes in either the strong or weak nuclear force would destroy nearly all the carbon or oxygen inside stars-making life impossible.
"The basic forces in the universe are tailor-made for the production of ... carbon-based life," Mr. Oberhummer told Space.com.
It's a new day when scientists who are not "religious persons" are compelled to use the language of design. Mr. Oberhummer's discovery adds to the enormous number of "cosmic coincidences" uncovered by cosmology-intricate balances among the universe's fundamental forces. For example, if the force of gravity were only slightly stronger, all stars would be red dwarfs, too cold to support life. If it were slightly weaker, all stars would be blue giants, burning too briefly for life to develop.
In the atom, the mass of the neutron is delicately balanced with that of the proton; otherwise, protons would decay into neutrons, making life impossible.
"Imagine a universe-creating machine, with thousands of dials representing the gravitational constant, the charge on the electron, the mass of the proton, and so on," said Steve Meyer of Whitworth College. "Each dial has many possible settings, and even the slightest change would make a universe where life was impossible." Yet each dial is set to the exact value needed to sustain life-for no known reason.
As Mr. Oberhummer put it, "we have no idea why the strengths of the forces are fine-tuned" to support life. The reasonable answer seems to be that someone intended it that way.
To avoid that surprising conclusion, cosmologists are scrambling to craft alternative explanations. Some adopt the "many worlds" hypothesis, suggesting that there exist an infinite number of universes. Most would be dark and lifeless, but by sheer probability a few might be suitable for life-and we happen to live in one.
How do scientists account for these zillions of universes? Some say mini-universes crowd together within a larger universe like bubbles in foam. Others propose an oscillating universe-continually expanding, collapsing, then expanding again to form new universes with different physical laws. Strangest by far is physicist Hugh Everett's notion that all possible states of a quantum interaction are actualized, so that slightly different versions of our universe are constantly splitting off-creating a near-infinitude of new universes at every moment.
What's the evidence for other universes? There is none. By definition, they cannot be observed. Nor has anyone offered a plausible scientific explanation for how they arise. "There is no hint as to what causal mechanism would produce such a splitting," complained philosopher John Earman-which renders it akin to a "miracle."
Moreover, the hypothesis violates the principle of simplicity. As Guillermo Gonzalez of the University of Washington told WORLD, "Invoking an infinitude of unobservable universes to explain the one observable universe is a grotesque violation of Occam's razor," the principle that entities should not be multiplied unnecessarily.
Other cosmologists try to explain design by a quasi-pantheistic philosophy that attributes intelligence and foresight to the universe itself. In The Fifth Miracle, Paul Davies says, "the laws of the universe are cunningly contrived to coax life into being"; they "somehow know in advance about life and its vast complexity." This year's Templeton prize-winner, Freeman Dyson, muses that "the universe in some sense must have known we were coming."
Of course, the idea of a conscious universe, or of unknowable universes sprouting like mushrooms, goes beyond science and into philosophy. This opens a new opportunity for Christians, says philosopher William Lane Craig. "Cosmology has broken down the boundary between physics and metaphysics," he told WORLD. "And once the door is opened to metaphysics, you can't stop the theist from coming in the door, too."
If the universe appears
"tailor-made" for life, perhaps the simplest explanation is that it was tailor-made.