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Jim, sorry, but you're wrong. Deutsch said, in the abstract to his paper that first proposed quantum computers: "Computing machines resembling the universal quantum computer could, in principle, be built and would have many remarkable properties not reproducible by any Turing machine." The paper was "Quantum theory, the Church-Turing principle and the universal quantum computer", and it can be found here: http://www.ceid.upatras.gr/tech_news/papers/quantum_theory.pdf Dylan On 17 Oct 2012, at 21:13, Jim Andrews wrote: > The Turing machine hasn't been redefined, Dylan. It's the same as it was when Turing dreamed it up. Lots has changed, of course, in computing over the last 75 years. But not the Turing machine. It is still the bedrock of the theory of computation. > > That quantum computers are fast enough to behave like Turing machines in parallel, Dylan, is simply to say that they behave like Turing machines, because n Turing machines operating in parallel aren't going to compute anything that a single Turing machine can't compute. The quantum device will compute Turing-computable things more quickly, but speed is not at issue. > > The question of whether quantum computing is truly a new paradigm of computing involves the question of whether it offers new computations that a Turing machine can never ever (never) compute. > > ja > > ----- Original Message ----- From: "Dylan Harris" <[log in to unmask]> > To: <[log in to unmask]> > Sent: Wednesday, October 17, 2012 10:34 AM > Subject: Re: David and Jim > > > Well, only because people cheated: the Turing Machine was redefined to accommodate quantum computers. An explanation is here: http://computer.howstuffworks.com/quantum-computer1.htm . > > On 17 Oct 2012, at 19:14, Jim Andrews wrote: > >> Quantum computing may offer computers of increased speed. We are used to computers getting faster. What it definitely does not offer is a form of computing that exceeds the theoretical capabilities of Turing machines. >> >> ja >> >>> and Jim--yes, all of that scientistic stuff. We discussed the new age >>> junk science in the class and and it's a commonplace (as David would >>> say) to dismiss it and it properly was. Quantum computing is a whole >>> different kettle of fish, though. It seems to promise a real >>> break-through. >>> >>> >>> Jess > > > Dylan Harris > > --- > http://dylanharris.org/ > H +352 2620 1731 > M +352 621 377 160 Dylan Harris --- http://dylanharris.org/ H +352 2620 1731 M +352 621 377 160