From: Eugen Leitl (eugen@leitl.org)
Date: Wed Aug 28 2002 - 15:33:34 MDT
On Tue, 27 Aug 2002, Terry W. Colvin wrote:
> But you ommit here the "information loss" (i.e. brain damage) associated
> with the freezing process. Evidence indicates that this is considerable
Considerable, yes. Will the scrambling destroy the structural information
encoding the you-process? We don't know. It doesn't look very good right
now, but we certainly can't say it is impossible. It's a gamble, and one
where you can improve your chances a lot by prior strategy.
> with current or forseeable techniques. We can't even freeze a kidney, let
> alone a brain...
Actually, I'm pretty certain we can freeze a human/rabbit kidney, and
achieve a better than 10% (off the wall number) of own graft long-term
survival. I'm not tracking what 21st Century Medicine is doing these days,
but I haven't seen any major showstoppers while being there. Tissue
viability looks very good indeed. Microsurgery on small critters is more
the difficulty here. However, I think the damage will be big enough so it
will fail to revolutionize the renal transplant business.
> And once the information is lost, even developing a thawing process that is
Similiar to death, information lossage is a nonboolean metric.
> 100% efficient and looses no information at all, you'll still have a badly
Fat chance.
> damaged brain. Remember that your brain will be frozen after you die, and
D00d, you died. And spent some time at normothermia. I'd assume that's
some damage.
> unlike other tissues which can survive for significant periods (hours or
> more) with no oxigen, brain damage becomes irreversible after a couple of
> minutes.
I'm sorry, but this is compleat bullshit. Try again. How does 15 of
normothermic ischemia sound like? And why do you assume that
"irreversible" has the same meaning in native biological context or in
DSP on molecular-resolution maps of vitrified flesh?
> Science is based on evidence. Evidence indicates that freezing your brain
> will destroy it, if it's not already too badly damaged even before the
Destruction is boolean. Rather try damage.
> procedure starts (do they guarantee they'll start freezing within a minute
> of your heart stopping?).
No. But you have a rather good chance if stabilization starts within a
hour. (If you can engineer your demise, chances become dramatically
better, as de facto euthanasia is being done even today).
> Although examples of great success like skin, corneas, sperm or embryos are
> given to show that it's possible to preserve complex tissues or organs this
> way, the reality is that these examples come from the best laboratory
> results, obtained among lots of failures. So you don't see cryogenic
> depositories of skin or corneas for transplants, and the only reason sperm
> and embryos fare well is that only a few cells need to survive the process
> in these cases.
True. But, the processes used are extremely crude.
> My conclusion is thus that cryopreservation of human brains is not science
> but misguided faith and quackery.
Cryonics is firmly mired in snake oil, cryobiology per se is not. One of
the tragedies is that the cryonics community feels no incentive to get out
of the cargo science business. Similiar to religion, it is very
comforting.
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