X-Message-Number: 13222
From: "john grigg" <>
Subject: the feasibility of cryonics...
Date: Tue, 08 Feb 2000 00:22:07 PST
Hello everyone,
Cryonics has become a thread on the extropians digest once again and I want
to share with all of you some of the best posts. They are definitely worth
reading. Extropians are not the die-hard cryonicists I would have initially
thought them all to be but they do bring up some excellent points. I look
forward to reading the responses from the Cryonet.
sincerely,
John Grigg
Date: Sun, 6 Feb 2000 12:36:59 -0800From:
Subject: Re: CRYONICS: feasibility [was Re: Fox cryonics show]
Robert J. Bradbury, <>, writes:
>What I want to know is are there people who have read Ralph's
>technical essay:> The Molecular Repair of the Brain
> http://www.merkle.com/cryo/techFeas.html
>and who *still* believe cryonics is infeasible?>
>By infeasible, I mean do you have concrete reasons to believe
>that something Ralph says is in gross error or missing in the
>details of how one would molecularly reassemble the damage caused by
>freezing? Another way of asking the same question is -- How
>can you believe that trillions of nanobots with collective
>ultra-human intelligence could *not* reassemble the 3D jig-saw
>puzzle left by your frozen brain?
I am signed up for cryonics, but I have never found this essay
completely convincing. It seems to gloss over the hard part, which
is the possibility of near-universal damage to the synaptic structures
which we believe encode memories. Cryonicist Mike Darwin has written
many times about the damage he sees to brain tissue which has been
cryopreserved using current protocols. He sees devastating damage,
ice crystals cutting everywhere, breaking and tearing tissues apart as
they grow, making things look like a bulldozer has come through.
Ralph writes of evidence that brain tissue can withstand conversion of
up to 60% of water to ice and maintain some level of functionality,
and says that current protocols have kept the ice level below 40%.
But these experiments are not able to rule out the possibility of damage
sufficient to eradicate memory. They are able to get some brain waves
and other evidence that neurons are functioning to some degree, but
there is obviously significantly damage.
Ralph also suggests that because synaptic structures are large, composed
of tens of thousands of atoms, that this will facilitate the task of
reconstructing them. However this size is meaningless if the damage is
occuring at this scale. If a large fraction of these 10000 atoms are
badly disrupted it may not be possible to figure out exactly how they
were arranged before freezing.
Most of the latter part of the essay discusses the feasibility of
measuring atoms and moving them around, and I am willing to stipulate
to that. It is the middle step here, where we use our computer models to
figure out where things were before the damage occured, that troubles me.
The best analogy I can suggest is that the brain may be like a city.
When it is frozen, it undergoes a terrible bombardment, and buildings are
damaged or destroyed, rubble lying in the streets everywhere. In the
aftermath, people can sweep up and get things going after a fashion,
piles of rubble here and there. It can function to a limited extent,
but it is not at all the city it was before. This is like the cat brain
spontaneously recovering brain waves.
To rebuild the brain is like a team of archeologists reconstructing
the city, figuring out where each piece of rubble goes, getting the
architecture back where it was. That's probably not going to be possible.
We can put something together that may look nice, but it is an educated
guess at best. Real cities have idiosyncracies and quirks, and when
those are lost in the rubble they will never be restored. What we end
up with is a ficticious city, one which has similarities to what was
there before, but the original city is lost forever.
I don't know that the brain necessarily works like this; maybe there
will be enough information for a full restoration. But it seems to me
that it is possible that this is the situation, and that this model is
consistent with the limited studies which have been done. If so then
Ralph's reasoning is incorrect, and from the available data we cannot
conclude that cryonics is especially likely to work.Hal
Date: Sun, 06 Feb 2000 14:59:16 -0600
From: "Eliezer S. Yudkowsky" <>
Subject: Re: CRYONICS: feasibility [was Re: Fox cryonics show]
Forget the problem of repairing the brain. Think of it in uploading
terms. The theoretical question is: "If you know where every single
atom in a frozen brain lies, could you extract an model of the brain's
operation with such high resolution that the informational damage caused
by freezing would not be significant (on a damage scale calibrated by
the effects of neural death and quantum/thermal randomness in day-to-day
operation)?" I think this sounds reasonable; damage to structure on the
>10^6-atom-scale may appear to destroy the information contained on that
level of abstraction, but the same information should still be
obtainable from the internal structure of the mostly-untouched inner
volumes of the 10^6-atom units being shoved around. If so, then the
practical question is extracting the information without causing exactly
the sort of atomic-scale disruption that would destroy that level of
abstraction as well.- --
Eliezer S. Yudkowsky
http://pobox.com/~sentience/beyond.html
Typing in Dvorak Programming with Patterns Writing in
Gender-neutral
Voting for Libertarians Heading for Singularity There Is A Better Way
Date: Sun, 6 Feb 2000 13:58:26 -0800 (PST)
From: "Robert J. Bradbury" <>
Subject: Re: CRYONICS: feasibility [was Re: Fox cryonics show]
On Sun, 6 Feb 2000, Eliezer S. Yudkowsky wrote:
>Forget the problem of repairing the brain. Think of it in uploading>
>terms.
Well Eliezer, not everyone may want to be reanimated as an upload.
Some of us might want to putter around the galaxy in our interstellar
star-hopper until we make some fatal mistake in navigation or alien
diplomacy. Its so much more romantic that way compared with dying
a thousand deaths in an SI VR.
>The theoretical question is: "If you know where every single
>atom in a frozen brain lies, could you extract an model of the brain's
>operation with such high resolution that the informational damage caused
>by freezing would not be significant (on a damage scale calibrated by
>the effects of neural death and quantum/thermal randomness in day-to-day
>operation)?"
This is pretty much the question I'm trying to get at. Hal responded
to some degree expressing his doubts. From my perspective, thequestions
are:
(a) Does the process of ice crystal formation develop enough force
to break interatomic bonds or will the crystals almost universally
disrupt H-bonds and Van der Waals interactions?
(b) What is the probability that within a some fixed (sub-cellular) volume
that I will have identical surfaces that preclude putting things back
together exactly the way they were originally?
With regard to (b), I find it hard to believe using nanodis-assemblers
that I could not remove all of the ice *entirely* (e.g. creating
approximately a freeze-dryed brain), then map all of the surfaces
and not discover *exactly* where the various synapses should be
positioned and setup the required repair operations. I'd envision
you would have nanobots carefully positioned around the broken
pieces, preprogrammed to slowly heat the tissue and execute vector
movements designed to properly reposition things. Only if the damage
includes the breaking of covalent bonds [e.g. (a)] does the process of
repair become more difficult (having to replace broken chromosomes,
proteins, etc.).> I think this sounds reasonable; damage to structure on the
> >10^6-atom-scale may appear to destroy the information contained on that
>level of abstraction, but the same information should still be
>obtainable from the internal structure of the mostly-untouched inner
>volumes of the 10^6-atom units being shoved around. If so, then the
>practical question is extracting the information without causing exactly
>the sort of atomic-scale disruption that would destroy that level of
>abstraction as well.
Since we seem to be able to do this level of "atomic" surface sensing
(molecular fingerprint recognition using AFMs) and you have things like
laser driven decomposition of surface layers (currently used for things
like DNA sequencing via mass-spec), this seems highly feasible to me.
Furthermore, taking apart a small number of cells will give you the
genetic blueprint (and consequently the 3D blueprint) of all of the
molecules (excepting perhaps viruses or nutrients) that should be
in the cells. I see this as no different from paleontology where
you can recognize a dinosaur from a fragment of bone sticking out
of a rock formation. My sense of the molecular biology of the brain
at this point is that you could probably destroy the contents of
every single cell so long as you did a highly accurate inventory.
Then once you get all of the cell membranes and synapses in place, you
fill the cell with water, repopulate the molecular contents andoff you go.
The contents of the cell is probably highly flexible as well.
I would guess that as long as you get things "balanced" sufficiently
that the cells will "run", you will be ok. The only places where
the contents is important are when you are dealing with internal
messangers involved in increasing synaptic strengths. Since you
"died" anyway, it will probably be like coming out of a coma
or a very deep sleep, so I suspect any disruption of short term
memory formation, because you don't get the molecule counts
completely correct, is going to be unimportant. You might end
up being a different person than you would have been had you
not undergone the suspension and reanimation but it begs the
question of whether or not some of us end up as different persons
because we experience high or low blood sugar once or twice a day.Robert
Date: Sun, 6 Feb 2000 19:04:49 -0800From:
Subject: Re: CRYONICS: feasibility [was Re: Fox cryonics show]
Robert J. Bradbury, <>, writes:
>This is pretty much the question I'm trying to get at. Hal responded
>to some degree expressing his doubts. From my perspective, the
>questions are:
> (a) Does the process of ice crystal formation develop enough force
> to break interatomic bonds or will the crystals almost universally
> disrupt H-bonds and Van der Waals interactions?
I am concerned about synaptic structure. I don't know how rigidly the
synapse is held together, but I suspect that a growing ice crystal could
separate, perforate and even shred the membranes. I would suspect that
cell membranes are not strong enough to withstand ice crystal penetration.
I have the impression that synapses are relatively gently bound together.
> (b) What is the probability that within a some fixed (sub-cellular)
>volume
> that I will have identical surfaces that preclude putting things back
> together exactly the way they were originally?
The problem is that the shapes may not match very well once the ice
is removed. As the ice is forming, the material around it is at least
a semi liquid. Water flows out of the cells and they would partially
collapse due to dehydration. The cells themselves would be shoved
around by the ice, tugged and torn, and their shapes will change.Hal
Date: Mon, 7 Feb 2000 00:29:52 -0800From: "Zeb Haradon"
<>
Subject: Re: CRYONICS: feasibility, and AI vision
If cryonics is physically/mathematically possible, then it is
technologically possible, and barring a return to the dark ages, will be
technologically feasible. What I mean by physically/mathematically possible
is that there may not be enough information in a frozen brain to interpolate
what the corresponding working brain looked like. Suppose my brain is
frozen, it changes from (unfrozen) state Z to (frozen) state Z'. If for all
(frozen) x', there is one-and-only-one corresponding (unfrozen) x, then a
few billion nanocomputers running in parallel and given a 3D scan of my
frozen brain (Z') should be able to figure out how to put everything back
together into Z. However, it may be that too much information is lost,
perhaps there are several different possible states that can result in a
frozen Z'.I toyed with the idea of proving that it's possible, today, using
AI
computer vision techniques. The idea would be to come up with a computer
vision program which can look at microscopic slides of groups of cells that
had been frozen and are suffering ice damage, and return a picture of what
the group of cells looked like before being frozen. Use a neural net, and
train it on several (thousand) examples, where you have photos of the cell
group both before and after freezing, so you can use the correct examples to
train the net. After much learning, if it's possible, and if it's designed
correctly and has enough computing power, it should be able to get it right.
Unfortunately, I know very little about implementing the techniques of
computer vision.
- --------------------------------------------------------------------------
Zeb HaradonMy personal website:http://www.inconnect.com/~zharadon/ubunix/
A movie I'm directing:http://www.elevatormovie.com
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