> On 5 Mar 2020, at 12:42, ronaldheld <[email protected]> wrote: > > Any comments, especially from Bruno, and the Physicalists? > > -- > 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] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/ff950ee5-b253-464e-b0aa-9eca73399b9c%40googlegroups.com > > <https://groups.google.com/d/msgid/everything-list/ff950ee5-b253-464e-b0aa-9eca73399b9c%40googlegroups.com?utm_medium=email&utm_source=footer>. > <2003.01807.pdf>
The paper is quite interesting, but I will have to deepen my understanding of Black Hole (and GR) to better appreciate it. There are some preliminary point were “I disagree” (or the universal machine disagree) but they might not be relevant, with respect to the paper, but relevant to the plausible link you make between the paper and physicalism. Typically, the first sentence of the paper is “physicalist”, which is not astonishing in this context. Susskind says that the original Church-Turing thesis may be regarded as a principle of physics (which it is not). This can be shown inconsistant with the mechanist assumption in Cognitive Science (not in physics). Indeed, with mechanism, a priori, the physical reality should be able to compute more than a Turing machine. The physical reality can simulate “real” random oracle, for examples, and any physical object requires the entire universal dovetailing to be determined. That entails non cloning, and a priori much more computability abilities (random oracle, “white rabbits”, infinite sum on infinitely histoiries, the full set of true sigma_1 sentences, but also non computable Pi_1 truth pertaining to the distribution of accessible states, etc. That is so true, that Mechanism must explain the apparent computability of nature from non computable subset of the arithmetical truth. So, here, implicitly the paper relies on physicalism, without the awareness that eventually the physical appearances have to be explained by the statistics on all computations in arithmetic, not just the “quantum one”, and the quantum must be extracted from the machine’s theory of consciousness (as I did). So, normally, it can be expected that the (original) Church-Turing thesis (which is one half of Mechanism) might imply the falsity of the quantum Church-Turing thesis (due to Deutch, and I have to think how much that is related to Susskind quantum-extended Church thesis). This concerns only the original Church Thesis and its impact on the possible physics available to arithmetical machine, and as physics is not yet entirely derived neither from Arithmetic, nor from observation (cf the GR + QM problems), it is hard at this stage to see how much mechanism will assess or diminish the validity of Susskind’s idea on the extended Quantum and physical version of CT. Yet, unlike the typical use of quantum mechanics to prevent an infinite computation to be realised in the physical universe, which would need digital state encodable below the Planck Era (and thus hardly usable by any concrete observer), the idea of Susskind is more subtle, and involves a notion of “complexity” related to the interior of Black-Hole. I would need here to revise (to say the least) Finkelstein derivation of GR from a finitist or discrete approach to Quantum Mechanics, which is still above my head … (I mentioned the interesting book by Selesnick on it sometimes ago). So, just to be clear: CT = anything computable is computable by a Turing machine (or by a combinator, or by Robinson Arithmetic, or by LISP, etc.). This has a priori nothing to do with physics. I will note s-CT for Susskind Physicalist version of CT: any thing physically computable is computable by a Turing machine. (The physical reality does not compute more). This is an open problem to me. It is not excluded that the physical reality which emerges from all computations in arithmetic might have non Turing computable components. Then s-ECT is the thesis that anything computable *efficiently* (i.e. in polynomial time) physically, by nature, is computable in polynomial time by a Turing machine. This thesis is usually believed to be wrong, as Susskind says, and indeed, if that was not wrong, we would not invest in quantum computing. Most people today believes that factoring (large) number cannot be done in polynomial time by a Turing machine. qECT (Susskind notation) is the (extended) thesis that says that if nature can compute efficiently something then a quantum computer can compute it efficiently. That is mainly what I call the Deustch Thesis. And as <I said, I do think that CT (+ YD, i.e. mechanism) entails its plausible falsity. And Susskind abounds in that direction, and this without Mechanism, which would make this into a yet another confirmation of Mechanism. With Mechanism, and assuming the existence of Black Hole, it should be obvious that whatever happens in a black hole will not play a role in the working of your brain. A good thing, as you will not have to ask to the Doctor to emulate the interior of a black hole. But with mechanism, this means that a black hole is full of "crazy virtual particles" doing infinitely complex task, just because your state of mind is totally independent of the”content of the black hole (without its boundary)". At first sight, Susskind seems convincing on this, but again, to be able to asses this would require that I study much more the QM and GR of the black hole. To compare with Mechanism, we have the rather complex task to derive GR from QM and QM from arithmetic before, so this is a bit premature (I still work hard to have a notion of space, although its shadow is there, but requires the existence of large cardinal in set theory. (As I said, with Mechanism, the ontology is extremely simple (Robinson arithmetic), but the phenomenology is of unbounded complexity. So, very interesting but complex idea by Susskind, but it touches on problem which are far from being treated with the mechanist hypothesis. If I progress in my understating of Finkelstein, I might say more later. The paper confirms that there is something in the holographic idea, and when you compactify a universal dovetailing, you get a sort of similar principle, given that the first person experience are determined only on its “boundary”. Bruno -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/3245BE5B-1382-4936-80C5-5A3D12D46AD2%40ulb.ac.be.
