Surfing the Gnarl by Rudy Rucker Read Free Book Online Page B

automata, Wolfram concluded that there are basically three kinds of computations and three corresponding kinds of natural processes.
    Predictable.
Processes that are ultimately without surprise. This may be because they eventually die out and become constant, or because they’re repetitive. Think of a checkerboard, or a clock, or a fire that burns down to dead ashes.
    Gnarly.
Processes that are structured in interesting ways but are nonetheless unpredictable. Here we think of a vine, or a waterfall, or the startling yet computable digits of pi.
    Random.
Processes that are completely messy and unstructured. Think of the molecules eternally bouncing off” each other in air, or the cosmic rays from outer space.
    The gnarly middle zone is where it’s at. Essentially all of the interesting patterns in physics and biology are gnarly. Gnarly processes hold out the lure of being partially understandable, but they resist falling into dull predictability.
    (3) Wolfram’s third tenet is that all gnarly computations are in fact universal computations. “Universal computation” is used in the technical computer-scientific sense of a computation that can in fact emulate any other computation. Universal computations aren’t at all rare. Every desktop or smartphone computer is a universal computer in the sense that it can, given enough time and memory, model the behavior of any other such computer.
    Given that physical processes are a type of computation, it’s natural that the virtual worlds of our videogames support a kind of artificial physics. The objects in these little worlds bounce off” each other, the projectiles follow trajectories shaped by “gravity,” the race-cars skid and spin out when they make overly sharp turns.
    Wolfram says we can turn things around. An interesting physical process is a gnarly computation, any gnarly computation is a universal computation, therefore any interesting real world process can, in principle, emulate any other naturally occurring process.
    In some sense we’re all the same: a cloud can emulate an oak tree, a flickering flame can model a human mind, a dripping faucet can behave like the stock market.
    If this strikes you as a strange way to think, you’re in good company. The universality of naturally occurring gnarly computations is something that the older generation of scientists finds baffling and outrageous.
    (4) Nothing of any significance in the natural world is predictable. Science’s dreams of ultimate mastery are self-aggrandizing horseshit.
    How so? As argued in point (3), all the interesting naturally occurring computations are gnarly computations, and these gnarly computations are universal computations with the ability of emulating each other. Given these facts, it’s possible, via some ironclad computer-science legerdemain, to prove that the interesting processes of nature are inherently unpredictable. The problem is that if you can predict the behavior of a particular universal computation, you run head-on into the Unsolvability of the Halting Problem, a paradoxical result proved by the early computer scientist Alan Turing in 1936.
    What, by the way, do I mean by “predicting a process”? This means to have some procedure for determining the processes result very much faster than the time it takes to simply let the process run. The point of result (4) is that there are no quick short-cut methods for finding out whata gnarly computation will do. The only way to really find out what the weather is going to be like tomorrow is to wait twenty-four hours and see. The only way for me to find out what I’m going to put into the final paragraph of a book is to finish writing the book.
    It’s worth repeating this point. We will never find any magical tiny theory that allows us to make quick pencil-and-paper calculations about the future. Sometimes scientists—or science-fiction writers—have speculated that