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).
Bruno 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 > > > > http://iridia.ulb.ac.be/~marchal/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to email@example.com To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---