X-Message-Number: 11003
Date: Thu, 31 Dec 1998 11:30:24 -0500 (EST)
From: Charles Platt <>
Subject: Expansion and Identity

> Message #11000
> Date: Wed, 30 Dec 1998 23:58:16 -0800
> From: Keith Rene Dugue <>
> Subject: Vitrification and Thermal stress
> To: Thomas Donaldson  Thermal stress is caused by differential
> coefficients of expansion and/or temperature gradients. Assuming the brain
> can be cooled isothermally ,differing coefficients of expansion in the
> brain should still cause some  thermal stress. How can this be eliminated
> or reduced? 

It's always a shock to see a substantial, immediate issue raised here. A 
pleasant shock, needless to say.

Different coefficients of expansion would of course create problems when
the temperature changes substantially and everything is in the solid
state. The question is, what ARE these coefficients of expansion for, say,
bone vs vitrified brain? Frankly I don't know, and I'm not sure that
anyone does know. I suspect a larger problem has been temperature
differential during cooldown. If the outside of a patient is 20 degrees
colder than the inside, you're going to get thermal stresses even if every
part of the body shares the same coefficient of expansion. 

Cryonics organizations generally cool the patient slowly, from dry-ice
temperature on down, in an attempt to minimize the temperature
differential. CI will tell you (as I understand it) that their procedure
is so successful, they have no, no, no evidence of cracking at all. Alcor
will tell you (as I recall) that their "crackphone" has detected many
events during a similar cooling procedure. Since I believe CI does not use
a detection device similar to Alcor's, I am unsure why they feel so 
confident. Maybe they can tell us here. 

One of the interesting asides at the 21st Century Medicine conference was 
from Brian Wowk, who noted that some of the new compounds he is working 
on may achieve vitrification at relatively high temperatures--ABOVE -79 
Celsius, the freezing point of carbon dioxide (dry ice). If this turns 
out to be true, storage will become cheaper, simpler, and possibly less 
liable to cause cracking.

Generally speaking I believe cracking has received relatively little
attention compared with other forms of freezing damage, because we tend to
feel that it will be easier to repair. Reassembling pieces of a person
should be considerably easier than inferring billions of connections in
the brain after neurons and axons have been decimated by millions of
microscopic ice crystals. 

Note: I am not a cryobiologist, and am self-educated in this field. The 
above paras should not be considered definitive.



As always, discussions of identity on CryoNet, while perennially popular,
are perennially pointless and constitute a distraction from the real
issues. We can ALL agree that identity is lost in two of the three
processes used after death: burial and cremation. We may ALL agree that
there could be SOME chance of identity being preserved by
cryopreservation. Therefore, obviously, the #1 task is to refine our
techniques of cryopreservation as much as possible. When we get to the
point where a brain can be preserved and then resuscitated without
significant damage, we will FIND OUT whether identity has been preserved,
which will render subsequent discussions irrelevant. I believe we may be
about 10 years from achieving this, but the people doing the work are not
the ones indulging in philosophical debates on CryoNet. 

--Charles Platt

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