hal@finney.org wrote:
> Sure, in principle, but then you are back to Eugene's super-gods who can
> reconstruct everyone from atmospheric molecule motions. Once information
> has degraded into heat, there is no practical technology which is going
> to be able to re-create that information. And such degradation is exactly
> what happens in chemical reactions that increase entropy. Distinguishable
> states transform into indistinguishable states. Macro scale information
> (at least at the molecular and structural level) changes into micro
> scale information (meaning heat).
Well, if you are talking about incinerating the brain, or dissolving it in
acid, or something equally drastic, I agree. But the kinds of injuries that
actually occur with any significant frequently aren't nearly that severe.
For example, a few hours of ischemic injury would leave a quiet recognizable
brain. You've got lots of molecules that have been degraded in some way
(denatured proteins, etc.), but the general structure of the cells is
preserved and most of the damaged components are pretty much where they
started. If you understand what healthy cells are supposed to look like,
and you know the chemical pathways that cause the damage, restoring the
tissue to its original state should not be a big deal.
> I maintain that given our current state of knowledge, we simply don't
> know whether there is sufficient information in frozen tissue to
> reconstruct its initial state to any particular degree of precision.
Hmm. I rather suspect that our real disagreement is here. IMO, current
evidence adequately supports the assumption that information storage in the
brain is not localized - i.e. that each bit is stored as part of the pattern
of interconnections of a very large number of neurons, rather than in the
state of some particular part of a single cell.
That means that you don't need to put every atom exactly back in its
original position to get a successful reconstruction. The important
features are relatively large, highly redundant structures containing vast
numbers of molecules. Obliterating those structures beyond recognition will
require far more damage than you would normally see - you'd have to drop the
brain in a blender, or do something equally drastic. I'm not sure how much
natural decay it would take, but it seems obvious that we're talking about
days or weeks rather than hours.
If, however, you believe that all of the fine structure within an individual
cell is important, that would make the problem much more difficult. Then
you would have to get each molecule back to exactly its original position
and state, so the amount of damage required to prevent reconstruction would
be much lower. I still think, however, that you make insufficient allowance
for the fact that reconstruction isn't limited to just looking at the frozen
tissue and following simple atom-shuffling algorithms.
Billy Brown
bbrown@transcient.com
This archive was generated by hypermail 2b29 : Thu Jul 27 2000 - 14:04:06 MDT