On 21 April 2018 at 16:44, John Clark <johnkcl...@gmail.com> wrote: > On Sat, Apr 21, 2018 at 4:10 AM, Telmo Menezes <te...@telmomenezes.com> > wrote: > >>> > >>> > >>> And Turing explained exactly precisely how to make one of his machines in >>> the real physical world >> >> >> > >> Nope. Turing machines have infinite tapes. > > > Nope. Turing machines don’t need infinite tape, they need sufficient tape, > if you start to run out of tape then add more,
And for the general case there will be instances where you always need more. > but after any finite number > of operations only a finite amount of tape is needed. > And with calculating > something like the Busy Beaver number only those machines that halt after a > finite number of operations count, Non-Turing universal machines can perform some computations. Even useful ones, for sure. > in fact in ANY successful calculation the > machine will eventually halt. while(true) { if (temperature < 21) { } } > Yes some machines will never halt (like the > Turing Machine programed to find the 7918th Busy Beaver number) and so you > will keep adding tape forever, but that is the very definition of > non-computability. But even in that case at any given time the machine only > has or needs a finite amount of tape. The non-computability of the Entscheidungsproblem is about the impossibility of having a computation that will tell you in finite time if an arbitrary other computation will ever stop or not. Computations realized in the physical world will always stop, because of physical limitations. If you apply to Turing the same demands that you apply to Bruno, you can only conclude that Turing was a moron for working on mathematical models that correspond to machines that cannot exist. In fact, for you the Turing Machine is not a machine because it cannot be physically realized. > >> >> > >> They were proposed by Turing as an >> *abstract* model of computation, >> and he was upfront about it. > > > Turing never claimed there were not far more complicated ways for an > engineer to make a computer, ways that worked faster and were far more > practical but were more difficult to understand. But he did show that any > computer could be reduced to his very simple machine, and people have > actually built real physical machines that work exactly as Turing said they > would. These machines are finite approximations of the machine that Turing defined, and which is not a machine according to your criterium because it cannot be built. > When Bruno does more than just write mathematical symbols on a piece > of paper and makes a working physical model of a "Löbian machine " (and I > don't care if its ridiculously slow and impractical ) I'll retract > everything I said and place Bruno’s name next to Turing’s on my list of > greats. All I want is to see a working model of a physical "Löbian machine " > that is the equivalent to this model Turing Machine: > > > https://www.youtube.com/watch?v=E3keLeMwfHY > > >> > >> You're a bully. > > And you are a delicate snowflake who can't handle scientific criticism, and > a fool too if you think Bruno has said anything profound. > > 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 everything-list+unsubscr...@googlegroups.com. > To post to this group, send email to everything-list@googlegroups.com. > Visit this group at https://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. -- 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 https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.