X-Message-Number: 26128 Date: Tue, 3 May 2005 10:04:28 -0400 From: Thomas Donaldson <> Subject: CryoNet #26122 - #26123 To Mike Perry: I should go to bed soon because its getting late here. However: 1. Quantum computers are no longer Turing computers by any reasonable interpretation. I hope we can build useful ones, but that also looks like a hard problem. 2. I haven't read Deutsch on this question, but I would certainly agree that in some sense (very loosely speaking) we are machines, but not Turing machines. We're even highly parallel. It does not take quantum mechanics to simulate a human brain. It WILL take processors which can do things no present processors can do, like change their connections (remember those connections are our memories), grow new ones, and get more processors when needed. 3. We will not have truly simulated a brain until our manufactured brain can actually deal not with a simulated world but with the real world that surrounds us. Even a working Turing machine fails this particular test: it or the person is in a box, unable to see anything but the notes passed to it. The fundamental problem with simulating the world is that to be consistent you end up simulating the entire Universe, and get buried in the mapping the whole world problem from the Jorge Luis Borges story --- though in practise our simulation is likely to fall apart because of errors, not matter how much care we take. An artificial brain is useless unless it can deal with the real world. It's even useless to itself: who wants to live in a doll's house? SO: in one way I agree with Bob Ettinger, in another way I agree with you. Even simulating an mammal's brain raises lots of problems which have not yet got solution and sometimes don't even have any thought given to them at all (too many computer people think that it's a very simple problem, and because they never try solving it, never learn of its subtleties). However I would still agree with you in the sense that an artificial brain is certainly possible. To what extent it will be superior to our present brains, and whether we'll ever seriously WANT to build an artificial brain, are different questions, yet again. Best wishes and long long life to all, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=26128