X-Message-Number: 13304
From: "john grigg" <>
Subject:  posts on the feasibility of cryonics....
Date: Fri, 25 Feb 2000 16:43:36 PST

I wanted to share with everyone some excellent posts from the extropian 
digest on the feasibility of cryonics.  I think there is some real food for 
thought here.  I am still looking forward to Eugene Leitl's upcoming study 
on the structural damage to  cryonically frozen brain structure.  Billy 
Brown took in my view a somewhat unrealistic view of things that was 
critiqued by Eugene Leitl and Hal Finney.  Charles Platt has already weighed 
in on his view of the post.  As much as I believe that cryonics will 
ultimately work, I do have problems with overly optimistic views of how 
brain repair and memory restoration will be something we can simply have 
late 21st century science take care.


sincerely,

John Grigg


Date: Mon, 21 Feb 2000 13:41:32 -0800 (PST)
From: Eugene Leitl <>Subject: RE: Why 
Cryonics
Billy Brown writes:
 > I'd go a lot further than this.  First off, accidents that destroy the 
brain
 > are fairly rare, so even if you die young your odds of getting a
 > halfway-decent suspension are pretty good.  It is pretty hard to die in a
 > way that prevents your body from arriving at a hospital within an hour or
 > less - just don't get yourself killed while you're off camping in the 
middle
 > of nowhere.
Uh, do you you have actual numbers for this brash assertion? Are you
claiming that essentially all patients are suspended after one hour or
less after death has occured (not pronounced)? Don't think so.
 > Second, and more important, most people have an excessively narrow view 
of
 > what constitutes an adequate suspension.  Remember, if cryonics patients 
are
 > ever revived at all, that means we're positing nanotech advanced enough 
to
 > repair any kind of physical damage.  The only thing that matters in that
 > situation is whether the information that defines your memories and
 > personality can be recovered from your brain tissue.
This sentence is insoncistent. Clearly there is physical damage that
is irrepairable (say, incineration, or a week stored at RT) which
destroys essentially all information about a particular individuum.
 > Now, what people tend to overlook is that the problem of deducing the
 > original information content of a scrambled brain is isomorphic to the
 > problem of deducing the information content of an encrypted message.  
Given
Another assertion. Based on what?
 > modern cryptographic techniques and abundant computing power, that means
 > that no non-random form of damage can prevent a successful revival.  A
Sure, you're already immortal. Why bothering with a suspension at
all? Future science will reconstruct yourself from trajectories of
atmospheric CO2. Or from a piece of apple pie, whatever is closer athand.
 > completely random encryption is unbreakable, and so is a completely 
random
 > source of damage.  However, very few types of physical injury produce 
truly
 > random changes at the molecular level.  If the history of cryptography is
Yeah, right.
 > any guide, we should expect that even the most subtle kinds of regularity
 > can be used to reverse the effects of even the most radical 
perturbations. >
 > What does this all mean in English?  Basically, that burning your brain
I could comment, but I don't want to offend anybody.
 > destroys information, but dropping a rock on it doesn't.  Most of the 
damage
 > sources that cryonicists agonize over, like freezing damage and ischemic
 > injury, are very regular in nature and hence should be very easy to 
reverse.
 > So, your odds of getting an adequate suspension are very high no matter 
how
 > you end up dying.
I knew cryonics was a religion, but I never saw it demonstrated so clearly.


Date: Mon, 21 Feb 2000 21:28:48 -0600From: "Billy Brown" 
<>
Subject: RE: Why CryonicsEugene Leitl wrote:
>Uh, do you you have actual numbers for this brash assertion? Are you
>claiming that essentially all patients are suspended after one hour or
>less after death has occured (not pronounced)? Don't think so.
Heavens, no.  I'm merely claiming that it is hard to die in such a way that 
you can't be suspended.  If you die of an illness, you'll probably be at a 
hospital when it happens.  If you die in an accident, odds are there will at 
least be paramedics on the scene by the time you go.  Since they do check 
for organ donor ID, that gives you an excellent chance of ending up frozen. 
Of course, you could always get buried in an avalanche, or die while scuba 
diving, or otherwise manage to evade the emergency medical care system, but
the number of people who go out this way is a very small fraction of the 
total death rate.
>This sentence is insoncistent. Clearly there is physical damage that
>is irrepairable (say, incineration, or a week stored at RT) which
>destroys essentially all information about a particular individuum.
My point was simply that information preservation is the only thing that 
matters.  Damage that makes you look really messed up, but does not actually 
destroy information, won't affect your chances of being reconstructed by 
mature nanotechnology.  This is an important point because information loss 
is not visible to the naked eye, and it is quite easy to rack up lots of 
nasty-looking but irrelevant incidental damage.
>  > Now, what people tend to overlook is that the problem of deducing the
>  > original information content of a scrambled brain is isomorphic to the
>  > problem of deducing the information content of an encrypted
>message.  Given>> Another assertion. Based on what?
I thought that one was obvious.  Well, let's try a comparison:
When decrypting a message, you have an unknown body of information (the 
message) that is known to be organized according to certain rules (the 
language of the message).  The information has been subjected to some 
complex series of nonrandom transformations (encryption), and the object of 
the exercise is to reverse those transformations and recover the original 
state of the information.
When reconstructing the mind of a cryonicist, you have an unknown body of 
information (the patient's memories and personality) that is known to be 
organized according to certain rules (human neurology and psychology).  The 
information has been subjected to some complex series of nonrandom 
transformations (ischemic injury and freezing damage), and the object of the 
exercise is to reverse those transformations and recover the original state 
of the information.Do you see a problem with one of the comparisons here?
>Sure, you're already immortal. Why bothering with a suspension at
>all? Future science will reconstruct yourself from trajectories of
>atmospheric CO2. Or from a piece of apple pie, whatever is closer at> hand.
Yeah, right.  Thermal noise *is* random, and no known or projected
cryptographic technique would be capable of reversing it.> Yeah, right.
>I knew cryonics was a religion, but I never saw it demonstrated> so 
>clearly.
Come now, Eugene, you can do better than that.  We've got plenty of
experience with advanced cryptography to draw on, thanks to the cold war. 
We've had people break seemingly solid codes time and again, by exploiting 
the tiniest nonrandom features of the encryption technology.  I'm merely 
claiming that we can apply the same mathematical techniques to the task of 
deducing the original state of a frozen brain.  Ischemic injury, AFAIK, is a 
very complex but highly ordered cascade of chemical reactions.  It seems 
perfectly plausible that you could simulate the process in reverse to figure 
out what the original tissue looked like. The same is true of freezing 
damage.  Using cryptographic analysis is just a different way of performing 
the same computation, like using a neural net instead of a procedural 
algorithm. Or maybe it was the rock-on-the-head comment that got you?  But 
all we're talking about there is low-velocity collisions - we could simulate 
that now if the number of particles involved weren't so large.  It only gets 
tricky if there is enough energy involved to give you chaotic phenomena like 
turbulence, and even that might not be a show-stopper.  After all, we've had 
at least one code broken because it used local barometric pressure readings 
to seed its random number generator, and weather is pretty darn chaotic too.
Billy 


Date: Mon, 21 Feb 2000 22:45:32 -0800From: 
Subject: RE: Why CryonicsBilly Brown, <>, writes:
>Ischemic injury, AFAIK, is a very complex but highly ordered cascade of
>chemical reactions.  It seems perfectly plausible that you could simulate
>the process in reverse to figure out what the original tissue looked like.
>The same is true of freezing damage.  Using cryptographic analysis is just 
>a
>different way of performing the same computation, like using a neural net
>instead of a procedural algorithm.
I think the problem with the cryptographic analogy is that cryptographic 
transformations are, by design, reversible.  All the information in the 
plaintext is intentionally preserved, in scrambled form, in theciphertext. 
However, chemical reactions are biased in the direction of increasing 
entropy.  The body's metabolic reactions have to constantly fight this trend 
in order to maintain order.  Once there is injury or death, the forces of 
entropy will come into play.  Increase of entropy means loss of information. 
  So I think it is likely that most injuries, including trauma, ischemic and 
freezing injury, will involve some loss of information.
The unanswered question is whether this information loss is sufficient
to obliterate personality, memory, and other important brain state.
I don't think we know enough at this time to give any sort of definitive 
answer to this question. This was my objection to the Ralph Merkle essay 
mentioned a couple of weeks ago; I thought he was excessively optimistic in 
claiming that the
answer was largely known.  But other people who have actually looked at 
frozen brains, including Eugene and cryonics "godfather" Mike Darwin, seem 
to have a more pessimistic view.  Hal
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