On 8/18/2011 1:40 PM, meekerdb wrote:
On 8/18/2011 8:26 AM, Stephen P. King wrote:
On 8/18/2011 10:31 AM, Bruno Marchal wrote:
Hi Stephen,
On 17 Aug 2011, at 16:08, Stephen P. King wrote:
Hi,
Recently a link was referenced that discussed how serial
sectioning of brains is being automated:
http://www.mcb.harvard.edu/lichtman/ATLUM/ATLUM_web.htm I have a
question about this. Will this technology yield a model of the
dynamics of brain activity or will it be another taxonomy of brain
structures? It seems that dynamics are completely missing from the
narrative about scanning and uploading our brains into Turing
Machines. How exactly is a topological map of the structure of the
brain contain any information about the specifics of brain activity?
At best it might allow us to toss out models of dynamics that
have implications that would contradict the topology structure, but
nothing at all about how the topologies evolve.
I don't find the references now, but I remember having read that
some animal, like frogs, can freeze and resume the brain activity
after that. Some experience on rat shows that long term memory is
preserved in freezing, and that during freezing the activity of the
brain is really near zero. Short term memory is not. A cryogenized
person might survive with an amnesia of the last 5-6 minutes.
The dynamic of the brain is coded in the neurotransmitter
concentrations, not in the ionic potential along the axions. That
might be an argument for saying that the comp subst. level *might*
be high.
Bruno
http://iridia.ulb.ac.be/~marchal/
Hi Bruno,
Freezing would not always destroy the potentials that generate
the dynamics, thus momentum information is preserved. The microtome
is measuring pure positions of the neurotransmiters, etc. Even if we
have a precise map of all the molecules, that information is
conjugate to the momentum information. To copy a mind we need both,
thus the conjugacy makes faithfull copying and uploading impossible.
There is an inherent upper bound on the resolution of the scan thus
indeterminacy and therefore, as you argue, we only bet that the copy
has 1p continuity (bijective isomorphism or faithful homeomorphism)
with the original. I believe that this is a key feature of your result.
Onward!
Stephen
But this is exactly the point Tegmark addresses in his paper. The
temperature of the brain is such that the thermal induced uncertainity
of orders of magnitude above the QM limit. So faithful copying at the
quantum limit cannot be relevant.
Brent
This is not even a quantum limit issue! The point is that the
scanning will only capture position information. That is insufficient to
define the potentials, gradients, etc. that are the dynamics, momenta,
etc. aspects. The HUP is just a version of the conjugacy that exists in
the classical regime that we see in the case Fourier transforms; the
conjugate of a collection of delta functions is not a *single* specific
set of sine curves. At best we have an equivalence class... My point is
that if we cannot even define the Hamiltonian from the position data,
how can we even start talking about unloading using microtome data?
Onward!
Stephen
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