On Tuesday, March 5, 2019 at 6:23:42 AM UTC-6, Bruno Marchal wrote: > > > On 5 Mar 2019, at 00:43, Brent Meeker <meek...@verizon.net <javascript:>> > wrote: > > > > On 3/4/2019 3:54 AM, Bruno Marchal wrote: > > > On 3 Mar 2019, at 20:43, Brent Meeker <meek...@verizon.net <javascript:>> > wrote: > > > > On 3/3/2019 4:52 AM, Philip Thrift wrote: > > >> > Here's an example David Wallace presents (as an "outlandish" possibility): > Suppose in *pi *(which is computable, so has a *program* (a spigot one, > in fact) that produces its digits. Suppose somewhere in that stream of > digits is the Standard Model Equation > > (say written in LaTeX/Math but rendered here) > > https://www.sciencealert.com/images/Screen_Shot_2016-08-03_at_3.20.12_pm.png > > So what could this mean? (He sort of leaves it hanging.) > > > Nothing. Given a suitable mapping the SM Lagrangian can be found in any > sequence of symbols. It's just a special case of the rock that computes > everything. > > > Even if rock would exist in some primitive sense, which I doubt, they do > not compute anything, except in a trivial sense the quantum state of the > rock. A rock is not even a definable digital object. > > > It's an ostensively definable object...which is much better. > > > Ostension is dream-able. > > > > > > If someone want to convince me that a rock can compute everything, I will > ask them to write a complier of the combinators, say, in the rock. I will > ask an algorithm generating the phi_i associated to the rock. > > > There is no particular phi_i associated to the rock. That's the point. > The rock goes thru various states so there exists a mapping from that > sequence of states to any computation with a similar number of states. > > > It is a mapping of states. It is like a bijection. You need something like > a morphism preserving the computability structure, which do not exist in > the rock. A computation is not just a sequence of states, it is a sequence > of states defined by the universal machine which brought those states. > > There are bijections between N and Z, but only Z is a group, because those > bijections does not preserve the algebraic structure. Similarly, there is a > bijection between a computation and a movie of that computation, but it > does not preserve the causal/logical relation between the states, which is > a universal machine for the computation, and just a linear order for the > sequence, without structure, of the states. > > > > Of course one may object that the actual computation is in the > mapping...but that's because of our prejudice for increasing entropy. > > > OK.Now, a bijection between a physical computation and an arithmetical > computation do preserve the computability structure, that is why we can say > that the arithmetical reality/model implements genuinely the computations. > > Bruno > > >

The bijection material [physical] computation ↔ arithmetical computation is like (New Testament) Paul's thesis: There's earthly bodies and spiritual bodies. "Not all flesh is the same: People have one kind of flesh, animals have another, birds another and fish another. There are also heavenly bodies and there are earthly bodies; but the splendor of the heavenly bodies is one kind, and the splendor of the earthly bodies is another. ... If there is a natural body, there is also a spiritual body." Spiritual or heavenly fictionalism is like arithmetical fictionalism: spirits (like numbers) do not exist. - pt -- 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.