X-Message-Number: 20902
Date: Fri, 17 Jan 2003 18:57:09 -0500
From: Francois <>
Subject: Reply to Yvan Bozzonetti's questions

>I am not a nanotech specialist, may be that is why I am somewhat dubious
>about its capacities. There are some questions about it:

I will do my best to give a good layman's answer.

>Assume there is one billion molecule in a cell, how much time a nano device
>would take to control and repair them? Seconds? Minutes? Hours? more?

No real need to assume a number of molecules here. A bacteria can make a
replica of itself in about 20 minutes. A complex cell, like an ameoba can do
it in a few hours. Repairing a damaged cell is probably less work than
making a whole new one, and nanodevices will probably be much more efficient
at manipulating atoms than a cell, just like a F18 jet fighter can fly much
faster than a sparrow. So I would say that a conservative estimate for a
repair time would be on the order of an hour, probably less.

>If life is taken as an example of natural nanotech, (something I disagree
>with...) then a nanodevice can't have a finner structure, both life and
>nanodevices are bottom limited by atomic scale. So a nano repair device
must
>be nearly as big as a cell. Is this true? if not why?

That is not true. For starters, a cell's volume is mostly water, and water
is not actually needed in the design of nanodevices. They can be made far
more compact, with finely interracting moving parts that can be efficiently
pacted very close together. A functionning repair nanodevice could be the
size a mitochondrion, or even smaller, and thus fit very comfortably inside
a cell. After all, a living cell can contain hundreds of mitochondria, so
adding one more object similar size to the bunch would make very little
difference.

>One nano device can repair only a small number of cells. If it takes three
>minutes to repair a cell and move to the next, at the 5th the first will
>starve to death for 15 minutes and will need a new round of repair work. Is
>is true? if not, why?

Nanodevices are not living things, in the sense that they are not made of
fragile protein working in a liquid water environment. The cryonics patients
will be frozen in liquid nitrogen. A nano device can be designed to work in
such a cold environment. They can therefore effect repairs on what will be a
solid and static object, the frozen cell. This will give them all the time
they need to proceed. Of course, a way to thaw the repaired body safely will
have to be divised. That is not a trivial problem.

>If nano repair robots are of cell size and as numerous as cells, how to put
>them all in the body? Where is the room for them?

As just explained, nanodevices will be much smaller than cells and will
easily and comfortably fit inside them. As to how to put them in, if they
are of the self replicating kind, you only have to start with one and
provide it with the raw material it needs to replicate. Through the "magic"
of exponential growth, you will soon have the needed number of nanodevices,
wich will then proceed to move to their intended locations on their own. Of
course, the whole procedure will require very sophisticated artificial
intelligence programs to control it.

>How to get them out? if there are tens of lbs of nanodevices, discard them
is
>not a simple task it seems.

You don't need to get them out. In fact, they should stay just where they
are. Each cell of the repaired body will contain its resident nanodevice
which will monitor it and effect repairs on a continuous basis. Aging and
desease will be a thing of the past. And there will be far less than ten
pounds of them. Because of their small individual sizes, I'd be surprised if
their collective bulk was much more than an ounce.

I hope these answers will be useful. I will probably not be the only one to
answer your questions and others will probably provide better and more
detailed explanations.

Francois
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