X-Message-Number: 21051
Date: Tue, 4 Feb 2003 06:19:01 -0500
From: Thomas Donaldson <>
Subject: CryoNet #21045 - #21050

For Mr Kluytmans, again:

The energy used to make an object is not the same as the energy
which may be stored in the object. You discuss diamonds as materials
for nanotech devices. Fine. What chemical (and other) energies 
are used in making those diamonds, remembering that some of that
energy will be lost and not recoverable from the diamonds themselves?
You do not cite any work which looks at this question. To be fair, we
have no nanotech devices of the kind you envision which would let
us use experiments to work out this energy. A valid argument for
nanotech substitutes for red blood cells would calculate the energy
needed to make them, not just the energy that remains with them
after they're made.

As for replacing our body parts with nanotech devices, it's 
appropriate to consider red blood cells as an example. The first
thing I would ask is that of just what evolutionary pressures
caused us to make only red blood cells with the lifespans they
have. I don't claim to be an expert on red blood cells and would
be interested in what such an expert might say. However I will
suggest that, given their role, making red blood cells capable 
not just of self-repair but also of fending off external threats
from viruses, bacteria, etc etc turns out to require more energy
and leave the red blood cells less efficient as carriers of O2
to our other cells. I would also ask if the red blood cells of
different species of mammal (not all animals use hemoglobin in
the first place) might have different lifespans. 

Finally, I will point out that if all our red blood cells are
replaced by nanotech substitutes, it would not take long (say
no more than 50 years) for bacteria, funguses, and other such
life forms to start growing on them. So just where would THAT
put us? Think of what's happened with all the antibiotics we've made.
Any good nanotech device of ANY kind would basically have to contend
with how everything in our world will change in response to it.

             Best wishes and long long life for all,

                  Thomas Donaldson

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