On 1 June 2015 at 13:32, John Clark <[email protected]> wrote: > On Sun, May 31, 2015 LizR <[email protected]> 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
