X-Message-Number: 12987 From: Date: Thu, 23 Dec 1999 16:30:17 EST Subject: simulation by clockwork Still another attempt to illuminate some problems with computer simulation: In our thought experiments, we need to get away from electronic computers, which tend to impress and bedazzle. Instead, think of strictly mechanical computers, like a Babbage engine or a Turing tape or a glorified abacus--clockwork. Its parts are cogwheels and rods and ratchets and driveshafts and disks and rollers and pistons and styluses etc. It might be driven by steam, or by electric motors powered by sunlight, but best to think of it as spring driven, like an old-fashioned watch. You just set it, wind it up, then stand back and observe. Physically impossible? Maybe not, if on the nano scale. In any case, we are only concerned with the principles involved. Now, what does a digital computer do? It generates numbers. It starts out with two stores--the program and the initial data, the latter representing the initial state of the simulated system, such as a person and his environment. Over time, the computer generates successive sets of numbers corresponding to calculated successive states of the simulated system. It is a serial computer. It only generates one new number at a time. Almost all the numbers it generates are intermediate steps in calculations or instructions, not new parameters of the simulated system. Even when a new number pertains to a new parameter of the simulated system, it usually pertains to only PART of that parameter, since any state or aspect of a state usually requires several numbers. Most of the time, nothing is happening--i.e., no meaningful number is changing; the machinery is just getting ready to shift another number. For example, maybe a pendulum is swinging--but that does not correspond to a change in the simulated system. The "simulation" changes only when one of the "meaningful" numbers changes, and even then only after the whole set of numbers for a particular parameter has changed. (If we need a specific example, a position vector cannot change until all of its new coordinates have been calculated, and these are calculated one at a time.) It ought to give you a queer turn also to remember that the assignment of labels to "meaningful" numbers is arbitrary to the programmer. How does the clockwork gadget (or the simulated subject) "know" which symbols (numbers) represent "real" parameters of a system and which represent something else, such as intermediate quantities in a calculation or instruction? One could argue--yes, we have been over this before--that the logic space is so dense (in some sense, so to speak) that only one possibility exists. The analogy would be an artificial language, built up in such a way that any intelligent alien, no matter how different from us, could not misinterpret it. But the analogy seems very, very fragile and unreliable. Even if the relationships could somehow be shown to be unique, we would still be left with the claim that feelings and thoughts and actions are (or can be) nothing but relationships between sets of numbers. Don't stake your life on that. Robert Ettinger Cryonics Institute Immortalist Society http://www.cryonics.org Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=12987