On 1 June 2015 at 13:32, John Clark <johnkcl...@gmail.com> wrote: > On Sun, May 31, 2015 LizR <lizj...@gmail.com> wrote: > > >> A Turing Machine does assume matter that obeys the laws of physics >>> >>> > It assumes that an infinite tape is available. >> > > A Turing Machine assumes a unlimited tape, that is to say if you start to > run out of tape you can order up more tape; it would only need an infinite > amount of tape if a infinite number of calculations were required. > > >> > A Turing Machine is actually an *algorithm* >> > > Yes, a algorithm that is a set of instructions that explains how to > organize matter that obeys the laws of physics in such a way that it can > make any finite calculation. >
It doesn't explain how to organise matter - which is obvious from the fact that all sorts of systems can be Turing-universal, including ones based on abstract sets of rules. The fact that to build one we have to use matter is a contingent fact; it has nothing to do with the (so-called) machine. Similarly (to take a simpler example) there are many ways one can add two numbers together, but that doesn't mean that addition is a material process. At best, addition is something we abstract out from a large number of different material processes (people operating abacuses, suitably trained brains thinking through the calculation, mechanical and electronic calculators, Bose-Einstein condensates, etc). Yet if performed correctly the calculation always gives the same result regardless of the physical medium used - which suggests that an abstract process is being instantiated physically, not that it is a physical process (if so, which one?). (As for the metaphysical leap, maybe you should try reading what I actually said and answering that? I know it's more difficult than answering something you've made up yourself specifically to be easy to knock down, but you could try it.) -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
