Actually Tegmark already proposed a similar no go theorem.

BTW, it is weird people that continue to talk about the Penrose- 
Hameroff argument.
Hameroff is OK with the idea that a brain could be a machine (of the  
quantum kind).
Penrose is not OK, with that idea. Penrose, in his book and papers,  
makes a proposition that brain are not machine, not even quantum  
machine, i.e. that brain are really not turing emulable. It is the  
only example of non-comp position made by a scientist. I recall, with  
Quentin recently, that quantum computer are Turing-emulable (albeit  
very slowly).


On 18 Aug 2009, at 13:33, Mirek Dobsicek wrote:

> Somebody might  be interested in ..
> PHYSICAL REVIEW E 80, 021912 2009
> Penrose-Hameroff orchestrated objective-reduction proposal for human
> consciousness is not biologically feasible
> From the abstract:
> ------------
>   Penrose and Hameroff have argued that the conventional models of a
> brain function based on neural
> networks alone cannot account for human consciousness, claiming that
> quantum-computation elements are also
> required. Specifically, in their Orchestrated Objective Reduction Orch
> OR model R. Penrose and S. R.
> Hameroff, J. Conscious. Stud. 2, 99 1995 , it is postulated that
> microtubules act as quantum processing units,
> with individual tubulin dimers forming the computational elements.  
> This
> model requires that the tubulin is able
> to switch between alternative conformational states in a coherent
> manner, and that this process be rapid on the
> physiological time scale. Here, the biological feasibility of the Orch
> OR proposal is examined in light of recent
> experimental studies on microtubule assembly and dynamics. It is shown
> that the tubulins do not possess
> essential properties required for the Orch OR proposal, as originally
> proposed, to hold. Further, we consider
> also recent progress in the understanding of the long-lived coherent
> motions in biological systems, a feature
> critical to Orch OR, and show that no reformation of the proposal  
> based
> on known physical paradigms could
> lead to quantum computing within microtubules. Hence, the Orch OR  
> model
> is not a feasible explanation of the
> origin of consciousness.
> -----------
> Mirek
> >

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