On Tuesday, March 5, 2019 at 6:23:42 AM UTC-6, Bruno Marchal wrote: > > > On 5 Mar 2019, at 00:43, Brent Meeker <[email protected] <javascript:>> > wrote: > > > > On 3/4/2019 3:54 AM, Bruno Marchal wrote: > > > On 3 Mar 2019, at 20:43, Brent Meeker <[email protected] <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 [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
