Re: Cryonics and information theory

From: Eliezer S. Yudkowsky (
Date: Mon Jul 07 2003 - 17:27:54 MDT

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    Rafal Smigrodzki wrote:
    > Eliezer wrote:
    >>One problem I have, though, is that it still looks to me like it
    >>would be better to just chop off the head and drop it into a bucket
    >>of liquid nitrogen as fast as possible.
    > ### Probably a bad idea. The freezing damage (microstructural) is extensive,
    > maybe reversible with some as yet not-invented technique, but quite possibly
    > too severe after all. Vitrification, and the, recently proposed by Alcor,
    > intermediate temerature storage at just below the glass transition phase,
    > should greatly reduce the damage, even including the gross fractures.

    on't tell me about "freezing damage". Tell me about information loss, in
    the information-theoretical sense of that term. I don't care about
    "fractures" or "damage" - tell me what happens to the configuration space.

    > ### You are correct to look at the problem from the information theory point
    > of view, but the specific application of your reasoning is IMO
    > inappropriate - freezing does much more damage in terms of information loss
    > (just a guess, prompted by looking at fresh-frozen brain sections)

    How can you guess this by looking at slides? You can sever a neuron and
    half and what matters is not that it has been torn in half, but whether
    the jagged edges uniquely identify the other piece of the puzzle. This I
    would expect them to do. Furthermore, one of the critical questions is
    how much information is subtly stored in molecular properties that
    correlate to pre-freezing conditions; how can you tell this by looking at
    a slide?

    But IANAB, so feel free to correct me.

    >>If dendrites and axons retract into the cell body within half an hour
    >>after the neuron has been starved of oxygen (!!!),
    > ### This is not true.

    Maybe I've got it wrong. What's the correct time?

    Eliezer S. Yudkowsky                
    Research Fellow, Singularity Institute for Artificial Intelligence

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