On Mon, Jun 1, 2015 at 5:46 PM, LizR <[email protected]> wrote: > 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, >
There are many ways to make a computer and Turing's 1936 paper said nothing about the practicalities and engineering details, but he did prove that the logical schematic of any computer can be reduced to something that we now call a Turing Machine; but you can't make a calculation with just a schematic, you need matter that obeys the laws of physics too. > > The fact that to build one we have to use matter is a contingent fact; > Yes, if you don't mind that your Turing Machine isn't actually making a calculation, or doing anything of any sort, then matter that obeys the laws of physics is unnecessary. > > 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. > Nobody has ever added two numbers together without using a physical process to do so, and nobody has the slightest idea of how non-material addition would even be possible. > > if performed correctly the calculation always gives the same result > regardless of the physical medium used > The calculations are all done in a different way, but without exception they all have one thing in common, they all need matter that obeys the laws of physics, otherwise nothing happens. >which suggests that an abstract process is being instantiated physically, > Which suggests a physical process that can be thought about abstractly. > > not that it is a physical process (if so, which one?). > How about F=MA ? A force accelerates the Turing tape until it is under the read head then another force stops it, then yet another force accelerates ink to form either a 1 or a 0 on the tape. John K Clark -- 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.
