X-Message-Number: 26862 Date: Sun, 21 Aug 2005 09:09:56 -0400 From: Thomas Donaldson <> Subject: answers to Yvan Bozzonetti For Yvan: 1. On the question of whether or not a parallel processor with N processors can be precisely simulated by one with M < N processors, I have no references but can point out some obvious examples: suppose that you a fleeing a tiger, and for that reason you have all your muscles and senses working SIMULTANEOUSLY on the task of fleeing the tiger. A single processor could not do even part of this task without failing to do its different parts simultaneously. Suppose each processor in the M processors was much faster than a single processor in the N processors. Yes, depending on what you have to do, you could use such a system to simulate some of the actions of the N processor brain, though it would be clear that close observation would show that the N processors were working simultaneously while the M processors weren't. Perhaps your machine could be fast enough to flee tigers. Still, sooner or later something would come along which the N processors could handle while the M processors could not: a barrage of cannon fire, missles, and other things much faster than tigers. 2. The internet is physically spread out internationally. Nor, when compared to formation of new connections in brains, does it work very fast. Your first task here is to compress the internet into something the size of a human brain; your second task is to make it work faster. And the internet also requires special software to work at all; this software would need to be modified so that it worked more like a brain. (I'm sure that all the users of the Internet would be delighted :-)). The crucial point here is the telephone wires or radio waves from satellites with which the Internet works. Since in many countries everyone already has a telephone, the Internet can use that system to make its connections. In a real brain, there may not be any connection between two neurons, so that it would need to be created, just like installation of a telephone (or setting up a standardized radio connection amid all the other such connections). 3. Synapses are complex. It's a separate question whether or not they work like parallel machines, with every single feature of a synapse working at once. I don't know of any neuroscience experiment which looks at that question: most work on synapses deals with issues such as their responses to different transmitter chemicals and what structures and chemicals produce those responses. A lot of complexity comes from the series of chemical responses a synapse makes to a chemical input. If you find parallelism in the operation of single synapses (I don't mean complexity but parallelism) I would certainly be interested. It would, of course, make our brains even more parallel than they are now, and increase the problem I discussed in 1). above. As for creating a computer simulation of a neuron, that would be interesting and valuable, even if we'll need to keep aware of the boundaries of that simulation ie. the points at which it fails. Point 1 above tells of one such point at which such simulations can fail. Best wishes and long long life for all, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=26862