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:


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.



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.



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.


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?



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