What is the most fascinating question in all of science?
My vote goes to the meaning of the so-called "anthropic principle," and, judging from the traffic to www.biologos.org, the apparent design of the universe intrigues a lot of people. The "anthropic principle" derives from a profound recognition on the part of science in the past few decades that our universe does not appear to have been an accident but rather fine-tuned for life. But what exactly does "fine-tuned" mean?
As science developed in the past few centuries, a most astonishing insight emerged: Everything going on in the universe—from the swirl of thoughts in your head to the chirping of the bird outside your window to the exploding of a distant star in some far-off galaxy—is empowered by just four different interactions: the familiar forces of gravity and electricity, including magnetism, and two nuclear forces, one responsible for the fusion reactions in stars like our sun and one that causes radioactivity.
Physicists have studied these four interactions extensively, and they are now well understood. The particular strength of each interaction is perhaps their most interesting feature. You have probably played with magnets and noticed that the magnetic force is much stronger than gravity, which certainly cannot pull apart magnets that are stuck together. In the formulas for these interactions, a number called a "constant of nature" specifies their strength. If you increase the value of this constant, the interaction—or force—grows larger, and vice versa.
For many years these forces were just numbers, part of the physicists' boring formulas. But in the past few decades all this has changed. Computer modeling makes it possible to see how the values of these numbers affect the structure of the universe, from the formation of galaxies to the structure of DNA.
Consider the strength of gravity. When the Big Bang occurred billions of years ago, the matter in the universe was distributed randomly. There were no stars, planets or galaxies; there were just atoms floating around in the dark void of space. As the universe expanded outward from the Big Bang, gravity pulled ever so gently on the atoms, gathering them into clumps that eventually became stars and galaxies. But gravity had to have just the right force. If the force had been a bit stronger, it would have pulled all the atoms together into one big ball, and the Big Bang—and our prospects for life—would have ended quickly in a Big Crunch. If gravity was a bit weaker, the expanding universe would have distributed the atoms so widely they would never have been gathered into stars and galaxies. The strength of gravity has to be exactly right to get stars to form. But what do we mean by "exactly"?
It turns out that if we change gravity by even a tiny fraction of a percent—enough that would make you 1 billionth of a gram heavier or lighter—the universe changes so much that stars, galaxies and planets do not exist. And, of course, without planets there would be no life.
The other constants of nature possess this same feature. Change any of them and the universe -- like Robert Frost's traveler -- moves along a very different path. Remarkably, every one of these different paths leads to a universe without life in it. Our universe is friendly to life but only because the last 15 billion years have unfolded in a particular way that led to a habitable planet with liquid water and rich chemistry.
People who have reflected on this have many different reactions. Some speculate there must be an infinity of different universes with every imaginable combination of properties; we just lucked out to be in a universe capable of having people in it. My favorite response to the fine-tuning of the universe, though, is that of Freeman Dyson, former physics professor at the Institute for Advanced Study at Princeton University and one of the most brilliant and interesting astrophysicists living today. "The more I examine the universe and the details of its architecture, the more evidence I find that the universe in some sense must have known we were coming," writes Dyson in his 1979 autobiography, Disturbing the Universe.
I asked Dyson if 30 years later, he still feels the same way about his oft-quoted phrase.
"Yes," he said, "though I hate the word `anthropic' because that refers exclusively to humans." The Greek anthropos means a man or a human. "What it says is that the universe has to be built in such a way that intelligent creatures can ask questions about it. It doesn't mean the universe was designed for humans. That's not what I intended to say. What it means is that the universe seems to be constructed in a way that it is hospitable to life and intelligence. I still think that's true."
(The full text of this interview is available here.)
The fine-tuning of the universe is a perfect example of the BioLogos perspective: God is working continually within, through and behind the unfolding patterns of nature to bring about God's intentions and purposes. Such a claim goes beyond science. Even Dyson, with characteristic modesty, is reluctant to claim too much. But reality is more than just science, and as Christians, we can celebrate in worship the marvelous character of the world that science has unfolded for us.