>-----Original Message----- >From: Bruno Marchal [mailto:[EMAIL PROTECTED] >Sent: Monday, June 20, 2005 1:33 PM >To: Norman Samish >Cc: [email protected] >Subject: Re: copy method important? > > > >Le 18-juin-05, à 20:36, Norman Samish a écrit : > > >> I'm no physicist, but doesn't Heisenberg's Uncertainty Principle forbid >> making exact quantum-level measurements, hence exact copies? If so, >> then >> all this talk of making exact copies is fantasy. > > >Many good answers has been given. And my comment will overlap some of >them. > >The most physicalist one is to referindeed to Tegmark's paper where he >justifies by Everett/decoherence that the evidence is that our brain, >when seen as an information handling computing machine, acts as a >classical machine. But comp makes physicalism wrong, and Tegmark's >answer cannot be "fundamentally" genuine. > > The importance of quantum decoherence in brain processes >M Tegmark 2000, quant-ph/9907009, Phys. Rev. E 61, 4194-4206 > 161 Why the brain is probably not a quantum computer >M Tegmark 2000, Information Sciences 128, 155-179 > > > >Then, concerning the comp 1-person indeterminacy, even if my >computational state is a quantum states, the Universal Dovetailer >Argument (UDA) is still going through. This is a consequence of the >fact that quantum computation does not violate Church's thesis. That >entails that you can simulate a quantum computer with a classical >computer. Sure, there is a relative exponential slow-down of the >computation, but this is not relevant because the universal dovetailer >is naturally slow down by its heavy dovetailing behavior, and then the >first person cannot be aware of that slow down. > >And then I recall I gave an exercise: show that with comp the >no-cloning theorem can easily be justified a priori from comp. As I >said this follows easily from the Universal dovetailer Argument.
But the UDA and the comp-hypothesis are not the same thing. >The >argument shows that physical observable reality (relatively to what you >decide to measure here and now) emerges as an average on all >computations (generated by the UD) going through your actual state. >Suppose now that you decide to observe yourself with at a finer and >finer level of description. At some moment you will begin to observe >yourself at a level below you substitution level (which I recall is the >level where you survive through copy). How do you know you can observe that level? >Below that level comp predict >you will be confronted with the 1-comp indeterminacy, that is you will >"see" the many computation/histories. If comp predicts that then it seems to involve a self-contradiction. It implies that there was no substitution level after all. Brent Meeker
