X-Message-Number: 13321
From: Eugene Leitl <>
Date: Mon, 28 Feb 2000 03:36:36 -0800 (PST)
Subject: Re: Message #13318

Charles Platt wrote:

> I think your assumption is not correct, Steve. I have received private
> email from Ralph Merkle (who apparently prefers not to get entangled in
> the discussions here) emphasizing the applicability of encryption
> algorithms, while acknowledging the limited onboard power of nanomachines.

Excuse me, Charles, but we're totally ignoring the relevant issue here
(some deja vu, anybody?). At first, the assumed navigation and
computation bottlenecks do not exist if use destructive imaging
(i.e. disassembling the system, transiently creating a molecular map
which we either use for extraction of a computational model, or, after
advanced digital retouche tricks, for reconstruction verbatim, in the
(still frozen) flesh). Time is not a problem, since the system is
being processed in the vitrified state, and processivity is also not a
problem since the tissue can microtomed into sufficient number of
sections which get processed in parallel. So here our ass is covered.

Ok? Now for the bad part: the cryptography analogy is unfortunately
totally bogus. The damage description in

	http://www.merkle.com/cryo/cryptoCryo.html 

bears only tenuous connection to reality, and the assumption that
there is no information loss in the system because "The laws of
physics are reversible, and so in principle recovery of complete
information about the original state should be feasible" is not valid.

Now, even assuming that Edward Fredkin's thesis about Digital Physics

   http://cvm.msu.edu/~dobrzele/dp/Publications/Fredkin/Finite-Nature/
   http://cvm.msu.edu/~dobrzele/dp/Publications/Fredkin/New-Cosmogony/

is true (despite no experimental evidence whatsoever, but we're on
CryoNet here so let this not deter us), and we're indeed living in
exactly such a universe, this is unfortunately not very helpful if the
information is still Out There, but is meanwhile spread over a
lightcone with (say) 100 lightyears radius, and is still receding
fast, at the quite formidable speed of light in vacuum, or whatever
upper speed the universe rule dictate). So, still assuming that we're
living in a reversible-rule universe, this requires the Omega point
with its Aleph-null MIPS (either as indiscriminate, brute force
resurrection as computational models, or reconstruction extracted from
the information contained in the collapsing, closed spacetime) to
work.

We're firmly on religious turf here. Deus ex machina, indeed.

I'm sorry for having to resort to this truly surreal out-of-this world
type of arguments, but unfortunately this is the type of (theoretical,
head-in-the-clouds, homing-in-on-the-irrelevant) argumentation type
prevailing here. Mea culpa, etiam.

So from the practical point of view there indeed are dissipative
physical processes, where information is erased. As a gedanken, drop
an arbitrarily shaped cube of sugar into your hot beverage, and stir
until dissolved. Can we computationally reverse the time arrow?
No. This wouldn't even work in a perfectly Newtonian world, barring
infinite precision of both measurement and computation.  ?   Exactly.

A construed example? Sure. Do information-erasure processes appear in
the frozen brain? Certainly. Let us take a look at the typical state
of a patient's brain:

   http://4.3.78.106/cryo/ccr8.jpg

This is a piece of rabbit hippocampus with the ice removed by
freeze-substitution process, seen in light microscopy (below scala is
in that heathen unit mm). Let us take a closer look:

   http://4.3.78.106/cryo/ccr3.jpg

To my layman's eye, the damage pattern is fractal, i.e. showing
self-similiarity on all scales. One could compute the fractal
dimension from the image, but that's not relevant here. Gauging from
the white/black pixel ratio, the compression ratio is high. 1:3, 1:4?
Exact figure doesn't matter now. Due to volume expansion during
freezing the pressures generated within occluded yet unfrozen regions
are very high. Displacement of structures is high amplitude, light
microscopic observations show anisotropic high velocity flow during
the freezing process. Ultrastructurally, because lipid bilayers are
self-assembling, when torn apart they form new (vesicular/lammellar)
structures, thus further destroying information about their original
shape. Alas, this is not exactly neatly shattered china, ready for
puzzlework. Please nobody now say "Reynolds number", because that's
strictly irrelevant. This is about as far from an isotropic macroscale
model as it gets. Then why not a bandersnatch.

Even after above caricature of an analysis, please do not attempt weak
humour, and mention "reversibility" to me.

So, that's the bad part. Is there a good part? Let's see. At first,
this is not vitrification. Vitrificiation does much better. (How much
better, I can hopefully soon demonstrate in high-res images, both
light and electromicrographs accompanied by lots of juicy prose by
gurus we all know and love instead of my embarrassing attempts. So,
hang on there).

What is missing, is information about what happens to the system at
molecular scale. Fortunately, technology marches on, so this is
knowable in principle.

   http://www.people.Virginia.EDU/~js6s/zsfig/figureindex.html

This is still technology in statu nascendi, and can be probably
modified to image in the bulk. We don't need better resolution than
what CryoAFM can provide. (Well, at least I call that good enough:)

   http://www.people.Virginia.EDU/~js6s/zsfig/salt1.jpg

The other part of the puzzle missing is how much structural details do
we need to reconstruct the function of the original molecular
machinery, and either confabulate an functionally equivalent meatspace
model, or a purely computational model in machina (yesss!). However,
chances are good we will know, relatively soon. The human genome
project is rapidly nearing completion, Blue Gene & bioinformatics
promises to help us making sense of all the sequence data, people have
recently started making all kinds of neat things like
      
   http://www.e-cell.org/
   http://www.nrcam.uchc.edu/

and generically neural simulation involving digitized neuranatomy is
making steady progress.

So the question whether cryonics can or can not work will be
anwerable, hopefully in the foreseeable future. Blanket optimism,
however, is less than helpful in the attempt of answering that
question.

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