X-Message-Number: 2266 From: (Thomas Donaldson) Subject: Re: cryonics: #2258-#2263 Date: Tue, 18 May 93 10:25:11 PDT About the proposed resuscitation scenario: 1. The newly created version of the patient should NOT be created in the frozen state. Thawing itself will cause fatal damage, even assuming that we can project from the patient's state to what that patient's state would be if frozen in a perfect condition. This point has been made before. 2. It will take more than AI alone to recover the patient from a map of the location of his/her molecules. We still need to understand a good deal more about just what the state of a live person is, chemically. We don't yet understand how memory works, nor IN DETAIL where it is stored. Therefore no amount of AI can tell us how to put it back there. Since such storage and even the detailed anatomy of the patient's nervous system will very likely be unique to that patient, simple comparisons with others won't help. Finally, one major problem still remains after these: since we don't under- stand memory, we have no firm idea whether it even still exists in the frozen patient. I myself, and I believe most cryonicists, have joined not because we feel that survival of memory is certain, but because some acquaintance with the LIKELY forms of storage has convinced us that memory will PROBABLY survive --- not that it will DEFINITELY survive :-( sorry! 3. The problem of understanding how we work, of course, is a problem in biology. The same is true about survival of memory. Preserving location of every molecule gives far too much extraneous information, since we are not so much the location of molecules as an ever-changing system within which our molecular parts are created and destroyed constantly. We have not summarized the state of a river by listing the position of its molecules. A human being, or a very intelligent computer, would need a good deal more information before he could describe that river simply on the basis of its molecules; that information could not be derived simply from the list. The reason is that from the list alone it's impossible to decide whether some concatenation of molecules is random or essential to the riverness of the river. And if an AI system DID understand rivers, it would not look for position of molecules but for the higher level features which characterize rivers. Those features (of which for human beings we still lack a complete understanding, or one sufficient enough to recreate an individual) which the AI system would want are these higher level ones. I'm not saying that AI systems couldn't do this because they were AI. That is a red herring. I'm describing what a repair system of any kind should look for, and what it needs to find it. The "river", for a frozen patient, is damaged. To do any repair the AI system must first examine many cases of undamaged rivers to work out just what is a river, and what an undamaged one looks like. It would then be able to seek out exactly the information it needs --- which is not in the positions of molecules but in SOME of their relationships to one another (and not precisely, either: a subset of their possible relationships to one another). Incidentally, verifying that one of a subset of relationships exists is a much harder computational problem than verifying position of molecules. It looks hard enough to me that the computational problem alone would make such a method of revival fail. Best and long life, Thomas Donaldson PS: About the last paragraph, an addendum. The problem I see is a combinatorial explosion: we aren't looking for individual molecules but for a relationship. If we have a list of molecular positions, then we must test all candidate subsets for this relationship --- and the number of subsets of a set is 2^N, where N is the number of elements of the set. In the case of a human brain, that number is very large ... Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=2266