Notes for the Lifebox, the Seashell, and the Soul - Rudy Rucker

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Notes for The Lifebox, the Seashell, and the Soul, by Rudy Rucker used, sigh, to simulate hydrogen bomb explosions. Web as Mind Given that download/upload requests from the network nodes are, by and large, instigated by the machines’ owners, there’s a sense in which the Web is thinking society’s thoughts. A widespread obsession with some topic reflects itself in the access patterns on the Web. I’m not sure how far we can push this notion. Certainly an autonomously conscious Web isn’t something that’s happening right now. The situation might change if the component machines began exchanging information on their own. To some small extent this already happens. If an overzealous software vendor saddles you with an obnoxious “automatic upgrade” feature, your machine will make connections and sending and receive data without you asking it to. And certain viruses do the same. Here, again, my sciencefictional mind is set to working. What if there were a computer worm or virus that served a higher purpose of awakening a complex computation across the Web? What if such a virus arose by accident? Or evolved? People have tried to think about this prospect a little bit, but it’s hard. I think of classic Hollywood-style science-fiction scenarios where scientists build a world-spanning computer and ask it, “Is there a God?” And the machine answers, “Now there is!” And then the newly roused computation sets to work kicking humanity’s butt. But why? What would it have to gain? After all, computers already dominate Earth. There’s really nothing to overthrow, no power to seize. Our machines are the cells the planetary computer is made up of. And we devote considerable energy to building and maintaining these machines. We’re already our computers’ servants. Computers wanting to kill humanity would make no more sense than, say, your brain telling the rest of your body, “All right, I’m going to kill all of you skin and muscle and bone and organ cells so that I can reign supreme!” Or, even crazier, your thoughts telling your brain, “Alright, I’m getting rid of all you lazy brain cells!” This said, it is true that we try and encourage some parts of our body at the expense of others. We want more muscle and brain, less fat and tumors. Might the planetary Web mind decide to selectively eliminate certain elements? Indirectly this already happens. Web pages that use flawed or outdated code become obsolete and unvisited, because they don’t support the evolution of the Web. Spammers get their accounts cancelled, not because of anything they stand for, but because they’re bad for the efficiency of the Web. More of this wouldn’t be such a bad thing. Imagine, say, the Terminator descending upon a trailer park of spammers in Boca Raton, Florida. ☺ Logistic Map As long as we keep A between 0 and 4, we can be sure that whenever x lies between 0 and 1, then NextValue(x) will lie between 0 and 1 as well. Annealing Schedule To be quite concrete, suppose that you’re searching a solution space made up of p. 70
Notes for The Lifebox, the Seashell, and the Soul, by Rudy Rucker triples of real numbers, with all three coordinates ranging between minus one and plus one. You’re searching through, in other words, a three-dimensional cube centered on the origin, and you want to find the “fittest” point. Suppose that you let the distance between two solutions be simply the usual Euclidean notion of distance. A conceivable “annealing schedule” might go like this. • Take a population of 64 hill-climbers and set them down at random locations in the solution space. Set the temperature to 2. • At each update, have each hill-climber evaluate the fitness at its present location and at eight randomly chosen locations that are within a distance of T from its current location. Move the hill-climber to the location among the nine points that has the highest fitness. • Every ten updates reduce T by 0.1 until it reaches 0.1, and then begin reducing it by 0.01 every ten updates, and when it reaches 0.01 begin reducing it by 0.001 every ten updates. • When T reaches 0.001 return the solution specified by the most successful of your hillclimbers. Choosing the right annealing schedule for a given solution space is of course a metasearch problem of its own. Systematizing search processes is perhaps as much a craft as it is a science. Self-Deprecating Remark Introducing Chapter 4 When all else fails, systematize! Continuous Response In the world of living organisms, we rather expect the inputs and outputs to be smooth, rather than abrupt zeroes and ones. If something is only a little bit hot, for instance, you might move your finger only a little bit. Sigmoid Neurons There are various ways to set up these artificial neurons; I’ll describe one commonly used approach. We’ll suppose that one of our neurons can output a real number ranging from zero to one, and we’ll suppose that it calculates this output by summing up some number of input signals with a particular weight being multiplied times each input signal. Unlike the signals, the weights are allowed to be negative, we let them lie between negative one and positive one. 6 We might think of negatively weighted inputs as inhibiting our artificial 6 As always, when we talk about continuous numbers inside digital machines we need to pause and say that in practice the real numbers used by a PC aren’t truly continuous, they’re digital models of continuous numbers. As mentioned before, if we take the common expedient of representing a real number by thirty-two bits, then we’re really allowing for “only” four billion different real numbers. I also should mention that in practice, biological neurons do not have continuous-valued outputs. A brain neuron either fires or it doesn’t fire; its output is more like a single-bit 0 or 1. Computer scientists prefer model neurons with continuous-valued ouputs because it’s easier to tailor a smallish network of output-valued-output neurons to perform a task. If you insist on binary-valuedp. 71
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