God, Artificial Life, and Summer Camp

When I was but a lad of 14 at summer church camp, one of our speakers was arguing for the existence of God, based on the state of the universe around us. “Look at all of this!” he said, indicating the trees, the fauna, and the people that surrounded him. “How could all of this have come to be by chance? Do you know how complex the human body is? One faulty gene, and our bodies wouldn’t work. And look at the planets! If the earth had been just a bit closer to or a bit farther from the sun, life would be burned out of existence or frozen. If gravity were just a fraction greater or weaker, the solar system wouldn’t hold together. If nuclear forces were different, the sun wouldn’t work. Life hangs by the tiniest of threads, and only exists because God painstakingly set everything up exactly the way it had to be for all of this to work!”

“That,” I thought to myself, “is a pretty lame argument. If there is a big control panel from which the universe’s physical laws can be set, they have to be set to something or another. And though even a slightly different setting wouldn’t result in the universe as we know it, it would result in some kind of universe, and some kind of life. By rolling the dice of Creation, it might be phenomenally unlikely that we would come up with what we see around us, but it’s unavoidable that we come up with something, and this version of the universe is no more unlikely than any other.” I left that camp at the end of the week with the smug self-satisfaction only achievable by 14 year olds who think they know more than anyone else.

Recently I’ve been reading Steven Levy’s Artificial Life, a fine survey of the field from its origins to the current state of the discipline. One of the interesting personalities Levy touches on is Chris Langton, who catalyzed the development of the field as a recognized scientific discipline. As part of his work, he created a huge number of “virtual universes” — systems within a computer that had their own laws that governed them and entities that inhabited them. These entities were just little bits of software, but sometimes behaved in startling and lifelike ways, growing, changing, and reproducing themselves.

As Langton’s experience with his artificial entities increased, he began to notice that some of his virtual universes were much better able to sustain his entities than others were. Where the rules of a universe kept information from moving around readily, his entities weren’t able to exhibit lifelike behavior — or indeed any behavior at all. (Remember, these universes were built inside a computer, so they consisted entirely of information.) It was analogous to taking a frog and freezing it solid, which quickly ends its lifelike behavior. When the rules allowed information to move too rapidly, the entities quickly broke down into chaotic, unordered behavior, just as a frog again stops displaying lifelike behavior if you put it in a blender.

But between these two extremes, Langton found a fairly narrow range in which his entities could move, develop, reproduce, and otherwise behave in a lifelike way. Only by carefully balancing the laws in his virtual universe between static and dynamic behaviors could he make it a hospitable place for life.

As I read that, I suddenly thought of the speaker at our summer camp long ago, and recognized that though the settings on the cosmic control panel might indeed fall anywhere, the range in which the universe could support life might well be a good deal smaller than I’d realized. If the real world and these virtual worlds of Langton mirror each other in that way (and work in the field seems to indicate that they probably do), then maybe that summer camp had something to teach an uppity 14 year old after all.