X-Message-Number: 3547
Date: Fri, 30 Dec 94 08:20:13 EST
From:  (Perry E. Metzger)
Subject: CRYONICS: "Flash Freezing"

 (J. Coetzee) says:
>I know cells can be be flash freezed and then revived. According to M. 
>Darwin activity should continue in these cells at a slow rate..
>If so, then if it was possible to flash freeze a living human and then 
>flash thaw him he should have not suffered damage from it. If this 
>assumption is correct then all research should concentrate on a cooling 
>method such as those used in computers with metal coolers. When an 
>electric current is reversed through it the metal cools off..

One wonders if Mr. Coetzee comes up with these incredibly, er,
interesting (I suppose thats a polite word) ideas on his own, or if he
uses a randomizing process -- he produces so many of them, after
all. Mentioning not only the notion of flash freezing big thick
objects, but mentioning the Peltier Effect as a way to flash freeze
these big thick objects, and also mentioning "flash thawing",
certainly deserves some sort of prize.

I would suggest that Mr. Coetzee answer his own question. Its very
easy to do. Heating and cooling of objects can be modeled with very
simple differential equations first developed by Isaac Newton that
operate on the trivial principle that the rate of cooling or heating
is proportional to the temperature difference. Model a human being as
a solid cylinder about thirty or fourty centimeters across and about
two meters long -- for simplicity you can just assume an infinitely
long cylinder until you get to the thermal stress part of the exercise
where it starts to count. Assume the same constants as water -- they
should be close enough for this purpose. The simply assume that the
outside of this cylinder is held suddenly at some low temperature --
pick your favorite cryogenic liquid's temperature -- with the entire
cylinder at some uniform temperature -- something around 35 degrees C
should be good enough for purposes of this exercise. You should very
quickly see how "flash" flash freezing ends up being. You can figure
out on your own the sort of thermal stresses being placed on the body
in question by this exercise -- thats part of the fun. Remember that
humans are made of widely varying non-uniform materials and will
experience far greater thermal stresses.

Then, just for fun, although the question would have been moot even
before you asked if you'd been thinking, I suggest you call up a
manufacturer of Peltier Effect cooling devices. You can figure out
from the constants for water how much heat you have to move out of
that cylinder of water to get it from 35 degrees C to some low
temperature -- and you can ask the manufacturer how much heat their
devices can move per unit time. Remember that to "flash" cool things
with your theoretical peltier-effect "flash cooler" you are going to
have to move all that heat in a flash. Not, of course, that it would
make any difference, as you would have calculated above the
impossibility of making use even of an infinite store of liquid helium
for this purpose.


Perry

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