X-Message-Number: 11236
From: Thomas Donaldson <>
Subject: various comments
Date: Tue, 9 Feb 1999 00:48:27 +1100 (EST)

Hi everyone!

This Cryonet raises several questions:

1. Greg Fahy and Brian Wowk deserve praise for their work in developing
   new cryoprotectants and additives for much better preservation than we
   now have. And I understand quite well why they want to give highest 
   priority to developing these methods into ones usable for suspension
   patients. As someone who has not yet been suspended, I too would want
   better methods for FUTURE suspensions to receive high priority.

   However we still have some responsibility to those suspended in the 
   past (and in the time between now and when these new methods can become
   usable). It's clear that even our best present methods do lots of 
   damage.

   However it remains useful to see just what remains as distinct from
   just what is lost. Finding areas that have been close to totally
   destroyed doesn't answer this need. The question I'm raising is not
   whether current technology can revive present suspension patients, but
   that of just what kind of technology might do that job --- or, in the
   worst case, a very firm proof that no technology could serve. To do 
   that we also need lots more information about just what
   cells/structures/biochemicals etc actually survive. I'm not asking for
   any mindless bleating about Nanotechnology. I'm asking instead for
   actual data, which means the result of very thorough examination of
   brains frozen by present techniques, including not only electron
   micrographs, but micrographs done with various stains to show up
   individual neural structures, gross anatomy, results of attempts to
   grow the neurons remaining separately, and so on and on.

   I will add that from what we now know about brains, the hippocampus
   in particular may be dispensable for suspension patients. Certainly it
   is just as necessary as a body is for anyone alive, but just like the
   body of a neuropreservation patient, it may not be necessary to
   preserve it. (Yes, there are other areas destroyed too, but we'll have
   to see what we have left that is NECESSARY, not just useful only when
   we are awake and alive). In case this isn't obvious, I'll add (for
   those who may not read PERIASTRON) that our hippocampus plays an 
   essential role in acquiring memories and recalling them --- but when
   suspended we are not doing either of these activities.

   And yes, the "neuronal weave" to which Mike refers is likely to 
   contain our memories. So what of it remains, as distinct from what is
   destroyed? As we learn more and more about the chemical structure of
   brains, for instance, the information needed to tell to just what
   neuron a loose fragment of a dendrite might belong has increased a good
   deal (no, we cannot do this now --- at least not yet).

   I will point out finally, for clarification here, that first, it is
   quite true that many of our personal memories of our own past may
   contain surmises and even falsities, that class of memories is only
   one among several different kinds. It falls under the heading of 
   personal declarative memory. It doesn't follow, nor do I believe, that
   all of our different kinds of memory contain the same kind of surmises
   and fictional "fillers". My knowledge that Moscow is the capital of
   Russia and Vienna the capital of Austria is a form of declarative
   memory, but does not have the same character. And I leave out entirely
   procedural memory, such as remembering how to do long division or
   ride a bicycle. 

2. More comments about Tipler and finite universes, etc:
   First, clearly the existence of 2 people in the same quantum state
   cannot mean that they have either the same past history or the same
   future history. If we are finite, then lots of paths lead to one
   identical finite state, and lots of other paths lead to different
   futures. (Remember that we need not retain our memories as we
   proceed along one of these paths). So just what is it supposed to 
   mean to say that we are in the same quantum state? This problem 
   becomes even more obscure if we suppose that the two people involved
   are in different locations. Does it mean that for a very short time
   the two people were identical? (If they are awake and looking at
   the universe, then at 2 different locations they will see different
   things, and so cannot be identical --- unless we want to somehow put
   them in special rooms, or keep them unconscious). 

   To be mathematical about it, so long as the set of times at which
   I am identical to Mike Perry has measure 0, I think it would be 
   inappropriate to attach much importance to identical quantum states.
   For practical matters, we can even make the measure larger but still
   a very small proportion of my total lifespan, and I'd still think it
   unimportant. Mike and I would remain very different individuals.

   So: just what is the importance of these quantum states? Or to put
   the question differently: if we define two people as identical if
   they are identical for even a very short time, then our definition
   fails to catch some essential features to the notion of "identity".
   Among other things, no one would join my possessions with those
   of Mike merely because we were identical for 0.00005 seconds. Not
   even Mike and I would agree to that (or with an interval that small,
   even realize that we were EVER identical).

			Best and long long life to all,

				Thomas Donaldson

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