Deus ex Machina
The world seems very solid when you stub a toe, and the suggestion that it might all be a mere pattern of bits appears downright silly. But even an idea that's not taken seriously or literally can have a powerful influence.
The clockwork universe was first of all a theological notion. A clock was thought to imply a clockmaker; and yet, once the clock was wound and set in motion, there was no further need for divine intervention. Thus the religion of the clockwork universe was a cool and inoffensive minimifidianism, with a creator but no presiding ruler. In a similar way, a computational theology might suppose a departed programmer, who clicked on the button marked "Go" and then walked away. But even without a meddlesome programmer on the scene, free will is hard to find in a computing or computed universe. Our actions seem to be ruled by an algorithm whose scope we cannot know.
Perhaps there is a way out. In principle, every detail of a computer's future can be deduced from its present state. Nevertheless, anyone who writes programs has occasionally been surprised by their behavior. Some of the surprises are unpleasant: They are bugs. From another point of view, though, surprises are the whole point of computation. If you could work out in your head everything a program might do, you would have no need to run it on a machine. This idea can be stated more strongly: Some programs are "incompressible," in that no shorter program yields the same result, and there is no faster way of learning what the program does than to run it from start to finish. If our program turns out to be incompressible, we may be acting in ways the programmer never anticipated.
Maybe we can even keep the program and dispense with the programmer. Just as the need for a clockmaker gradually faded from the clockwork universe, perhaps a computational universe could evolve without a computermaker. There is much interest lately in self-organizing systems, emergent computation and evolutionary algorithms. What these buzzwords have in common is the theme of computations done without any need for someone to specify the program in full detail. One of these ideas might allow us to compute our lives away in comfortable anonymity and autonomy.
And a further flight of metaphysical fancy can wipe out the last traces of computational creationism. In the tower of simulations built upon simulations, the ever-nagging question is who built the computer at the top of the tower. But an obvious topological trick will rid us of this inconvenience. Simply wrap the tower around and connect the bottom to the top, forming a vicious circle. In this ring of worlds, we simulate ourselves.
© Brian Hayes